Journal of Double Star Observations

Transcription

1 University Journal of Double of South Star Observations Alabama Journal of Double Star Observations Page VOLUME 8 NUMBER 1 January 1, 2012 Inside this issue: The Relative Proper Motion of G in the Constellation Boötes Joerg S. Schlimmer Astrometric Measurements of the Visual Double Star δ Boötis Chris Estrada, Aaron Gupta, Manav Kohli, Alyssa Lund, Andrew Stout, Bevin Daglen, and J. Joseph Daglen Visual Measurements of a Selected Set of 20 Double Stars Kodiak Darling, Kristy Diaz, Arriz Lucas, Travis Santo, Douglas Walker Double Star Measurements at the Internationale Amateur Sternwarte (IAS) in Namibia in Rainer Anton Chico High School Students' Astrometric Observations of the Visual Double Star STF 1657 Jonelle Ahiligwo, Clara Bergamini, Kallan Berglund, Mohit Bhardwaj, Spud Chelson, Amanda Costa, Ashley Epis, Azure Grant, Courtney Osteen, Skyla Reiner, Adam Rose, Emily Schmidt, Forest Sears, Maddie Sullivan-Hames, and Jolyon Johnson A New Companion for STF 2590, WDS Micello Giuseppe Divinus Lux Observatory Bulletin: Report #24 Dave Arnold Astrometric Measurements of Seven Double Stars, September 2011 Report Joseph M. Carro Separation and Position Angle Measurements of Double Star STFA 46 AB and Triple Star STF 1843 ABC Chandra Alduenda, Alex Hendrix, Navarre Hernandez-Frey, Gabriela Key, Patrick King, Rebecca Chamberlain, Thomas Frey Comparison of Data on Iota Boötes Using Different Telescope Mounts in 2009 and 2010 by the St. Mary s School Astronomy Club Holly Bensel, Ryan Gasik, Fred Muller, Anne Oursler, Will Oursler, Emii Pahl, Eric Pahl, Nolan Peard, Dashton Peccia, Jacob Robino, Ross Robino, Monika Ruppe, Peter Schwartz, David Scimeca, Trevor Thorndike 351 New Common Proper-Motion Pairs from the Sloan Digital Sky Survey Rafael Caballero

2 Page 2 The Relative Proper Motion of G in the Constellation Boötes Joerg S. Schlimmer Seeheim-Jugenheim, Hessen, Germany js@epsilon-lyrae.de Abstract: G is a high proper motion star in the constellation Bootes. The study of the relative proper motion is pictured over an epoch of 97 years. Different sources will be used for recalculation the proper motion. The result of recalculation shows an improvement of proper motion which is given by μx = / year for right ascension and μy = / year for declination. The high proper motion star G (coordinates: ) can be found at a distance of about 300 arc seconds from δ Bootis. The star was found by the Lowell Proper Motion study in 1964 by comparison of star fields from different epochs. G is the 29 th proper motion star of plate 167, which was centered on STT192 in Corona Borealis. The study gives a brightness of 15.0 magnitudes and a proper motion of 0.40 arc seconds with direction of 193 degree [H.L. Giclas, R. Burnham, Jr., N.G. Thomas, 1964]. G is also listed in the LSPM catalog. The LSPM study gives a brightness of magnitudes and a proper motion of arc seconds in R.A. and arc seconds in declination (φ = degree). The distance is 26.6 pc = 86.8 light years [Lepine S., Shara M., 2005]. The following figures show the proper motion of G for the last 97 years. All figures are aligned to the angle conventions of double star observations. Figure 1 was made by F. Kaiser in 1914 on observatory Landessternwarte Heidelberg-Königstuhl with the Bruce astrograph (Figure 5). The Bruce astrograph is a double telescope and has an aperture of 2 x 0.4 m and a focal length of 2 m. To recognize plate errors in this early stage of astrophotography two Figure 1: Detail of photo from Bruce astrograph of 1914, observatory Landessternwarte Heidelberg-Königstuhl, G is marked with lines, image was taken from HDAP, notes were added by the author

3 Page 3 The Relative Proper Motion of G in the Constellation Bootes Figure 2: Detail of photo from Bruce astrograph of 1961, observatory Landessternwarte Heidelberg-Königstuhl, G is marked with lines, image was taken from HDAP Figure 3: Detail of POSS2 image of 1994, Oschin Schmidt telescope, Mount Palomar observatory, taken from The Digitized Sky images were recorded. Therefore two independent images can now be analyzed for each record. A third telescope with a focal length of 4 m was used for tracking control. The quality of the scanned Bruce plates is about 1 arc second per pixel. In Figure 1, G is below the neighborhood stars. Figure 2 is also from observatory Landessternwarte Heidelberg- Königstuhl. It was made in 1961 by G. Klare. The Bruce astrograph was also used. This time all stars were in line. It is also near the time of closest approach to one of the neighborhood stars. Figure 3 was made by the POSS 2 survey in 1994 with the Oschin Schmidt telescope and G has moved straight through the neighborhood stars. The scale of the scanned POSS2 images is also 1.0 arc second per pixel. Figure 4 was made by the author in An 8 inch Newtonian telescope with a webcam was used. The webcam was placed in the primary focus with a focal length of 800 mm. The figure shows the result of 100 stacked frames. For scale calibration the distance of both neighborhood stars was used. These stars (labeled as B and C) show no variations in distance or position angle over the epoch. The image scale is about 1.2 arc seconds per pixel. For plotting the relative proper motion, first the position angle of the measurements is procession cor- Figure 4: Detail of webcam image, made by the author in 2011 with 8-inch Newtonian telescope

4 Page 4 The Relative Proper Motion of G in the Constellation Bootes Table 1: G AB (Position angle is not yet precession corrected Source PA SEP DATE B3473a B3474b B9000a B9001b POSS2/UKS TU red image Author 8-inch Newtonian Table 2: G AC (Position angle is not yet precession corrected Source PA SEP DATE Figure 5: Photo of the Bruce astrograph made by the author in 2009, left astrograph with plate B, right telescope is for tracking control, behind it is the second astrograph with plate A B3473a B3474b B9000a rected to J2000. The maximum correction is about 0.15 degree. Then, the data are transformed from polar to Cartesian coordinates. A linear fit is calculated with the Gaussian method of least squares. The value of proper motion was calculated from measurements of 1914 (averaged over the values from both images) and Table 1 gives the position measurements used in this study for G AB, Table 2 gives the position measurements used for the AC components, Table 3 gives the position measurements for the BC components. In all cases the position angle is not precession corrected. The proper motion values of this study are given by the averaged values of AB and AC (see Figures 6 and 7). The result of recalculation of the proper motion from these data sets is different to the current values in literature (see Table 4). In comparison with the Lowell study the recalculation shows an increased angle but a degreased value for proper motion. Compared with the LSPM values, the value for proper motion is similar but the direction shows a difference of about 10 degree. B9001b POSS2/UKS TU red image Author 8-inch Newtonian Table 3: G BC (Position angle is not yet precession corrected Source PA SEP DATE B3473a B3474b B9000a B9001b POSS2/UKS TU red image Author 8-inch Newtonian calibr. (Continued on page 5)

5 Page 5 The Relative Proper Motion of G in the Constellation Bootes Figure 6: Proper motion of G AB. Polar coordinates for closest approach: s = 17.7 as; pa= degree Time of closest approach: T0 = Proper Motion: μx = as/yr; μy = as/yr; φ = degree Figure 7: Proper motion of G AC. Polar coordinates for closest approach: s = 30.6 as; pa= degree Time of closest approach: T0 = Proper motion: μx = as/yr; μy = as/yr; φ = degree Table 4: The relative Proper motion of G Source date μx μy μ φ H.L.Giclas LPSM catalog This study Acknowledgements This research has made use of the SIMBAD database, operated at CDS, Strasbourg, France This work made use of the HDAP which was produced at Landessternwarte Heidelberg-Königstuhl under grant No of the Klaus-Tschira- Foundation References H.L. Giclas, R. Burnham, Jr., N.G. Thomas, 1964, Lowell Proper Motions VI: Proper Motion Survey of the Nothern Hemisphere with the 13-inch Photographic Telescope of the Lowell Observatory, Bulletin / Lowell Observatory; no. 124, v. 6 no. 5, p Lepine S., Shara M.M., 2005, A catalog of northern stars with annual proper motions larger than 0".15 (LSPM-NORTH catalog), Astron. J., 129, Centre de Données Astronomiques de Strasbourg, SIMBAD Astronomical Database, The POSS2 image was taken from The Digitized Sky, Association of Universities for Research in Astronomy, HDAP, Heidelberg Digitized Astronomical Plates, positions/q/form

6 Page 6 Astrometric Measurements of the Visual Double Star δ Boötis Chris Estrada Allen Hancock College Aaron Gupta, Manav Kohli, Alyssa Lund, Andrew Stout and Bevin Daglen Oregon Episcopal School J. Joseph Daglen College of Idaho Abstract: During the summer 2010 Astronomy Research Seminar at Pine Mountain Observatory, a group of students from Oregon Episcopal School met with three goals in mind: to learn essential skills necessary for astrometry, to observe and measure the double star δ Boötis and compare their results with published literature, and to use proper motion vectors to determine the type of double star. The astrometric eyepiece was calibrated using the drift method. The separation and position angle of δ Boötis was determined respectively to be 109 and These where compared with data in the Washington Double Star catalog and found to be within 5% of previous measurements. Figure 1: Left to Right:10-inch F6 equatorial scope, Alyssa, Bevin, Andrew, Aaron, Manav, Joseph, and (kneeling) Chris Introduction One of the double star observational teams at the summer 2010 Astronomy Research Seminar at Pine Mountain Observatory consisted of students and faculty from Oregon Episcopal School in Portland and J. Joseph Daglen, a retired physician and teacher from Caldwell, Idaho (see Figure 1). They met with their team leader, Chris Estrada, for guidance on double star observations. The students had very little experience with double stars and astronomy. Joe Daglen had previous experience with astronomy and helped the team by sharing his knowledge. This project s three goals were: 1. To familiarize students with methods used by astrometrists, including the process of collecting data, calibrating the eyepiece/telescope using the drift method, and determining the separation and position angle of a double star. 2. To give the students the opportunity to make their first quantitative measurements and use formulas to estimate the precision of the observations to determine if the observations were accurate in comparison to literature data (Johnson, 2008). 3. To determine if the double star is an optical pair or a gravitationally bound binary system by using proper motion vectors.

7 Page 7 Astrometric Measurements of the Visual Double Star δ Boötis The double star δ Boötis was chosen based on its sizable separation and large disparity in luminosity between the primary and secondary stars. Such differences enable the observer to clearly distinguish between the two stars (Haas, 2006). By continuously collecting data from binary star separations and position angles over extended periods of time, their orbits and periods can be determined (Johnson & Genet, 2007). Calibration The primary goal of the calibration process was to determine the number of arc seconds represented by each division on the linear scale of the astrometric eyepiece. Alpha Cephei (Alderamin) was chosen to calibrate the astrometric eyepiece because its declination was between the recommended values of 60 and 75. The calibration star was aligned with the linear scale to begin the drift procedure. The drift method included aligning the calibration star with the linear scale, turning off the motor of the telescope, and then recording the time it took for the star to travel from the first to the last division (Teague, 2004). Although the entire group was involved in the drift procedure, only three students conducted each trial. The first student observed the star through the astrometric eyepiece and signaled when the star passed through the first and last divisions on the linear scale. The second student recorded the time (to the nearest 0.01 second) it took for the calibration star to pass through the linear scale, while the third student recorded the data. However, there was only one timekeeper and one recorder for the entire calibration process in order to reduce bias. Although the group conducted 16 trials, two were omitted due to wind interference. The average drift time was seconds and the standard deviation of the drift time was found to be 1 second. The group used the drift times to determine the number of arc seconds per division on the linear scale (the scale constant) of the astrometric eyepiece. The equation used to determine the scale constant was: t cosδ Z = 60 where is the earth s rotational constant in arc seconds per second, t is the average drift time, cosδ is the cosine of the declination of the star, and 60 is the number of divisions on the linear scale (Estrada et al., 2010). We found that there were 13.4 ± 0.1 arc seconds per division on the linear scale of our telescope, the standard deviation of the scale constant was 0.1 arc seconds per division, and the standard error of the mean was arc seconds per division. Separation The separation between the primary and secondary stars was measured by positioning and rotating the astrometric eyepiece so that the linear scale passed through the two stars. The number of divisions between the primary and secondary stars was estimated to the nearest 0.1 of a division and recorded. To avoid bias, the telescope was adjusted so that the primary star lay in a different portion of the linear scale for each trial. A major division on the linear scale was placed between the primary and secondary stars. The division was used as a zero point from which divisions were estimated left and right on each star. The measurements from the zero point were then added together to yield the total number of divisions. A total of sixteen trials yielded an average of 8.15 divisions between the stars. This figure was then multiplied by the scale constant (13.4 / division) obtained during calibration. Thus, the average separation was 109, its standard deviation was 0.44, and the standard error of the mean was Position Angle To obtain position angle using the drift method, the primary star was first set in the center of the linear scale of the astrometric eyepiece (Frey & Frey 2010). The clock drive was subsequently disabled, allowing the primary star to drift toward the protractor scale on the outer ring of the eyepiece. The angle where the primary star passed through was recorded to the nearest 0.5 degree. Although 16 trials were recorded, one outlier was eliminated due to novice error. The remaining 15 trials yielded an average of 164.4, a standard deviation of 0.9, and standard error of the mean of The data was then corrected for the Celestron eyepiece, providing a final position angle measurement of 74.4 ± Analysis According to previous literature from the Washington Double Star (WDS) catalog, the last measured separation angle for δ Boötis in 2009 was 104.7, and the position angle was 78 (Mason, 2010). This study s measured separation of 109 is 4.3 (~4.5%) greater than those of the last recorded measurement. The measured position angle of 74.4 is 3.6 (~4.6%) less than the last recorded measurement. According to Ronald Tanguay (1998), these differences of less than

8 Page 8 Astrometric Measurements of the Visual Double Star δ Boötis 5% between our measurements and past measurements suggest that our data can be considered of reasonable accuracy. The proper motion vectors cataloged in the WDS catalog from 2009 show the primary star of δ Boötis to have a proper motion of +85 arc seconds per 1000 years in right ascension, and -111 arc seconds per 1000 years in declination. The secondary star was reported to have a proper motion of +84 arc seconds per 1000 years in right ascension and -110 arc seconds per 1000 years in declination (Mason, 2010). This difference of only one milli-arc second per year in both right ascension and declination strongly suggests that the primary and secondary stars are a gravitationally bound system moving together through space (Grocheva & Kiselev, 1998). Conclusions As mentioned earlier, the goals of this project were for students to gather and communicate original data regarding the double star δ Boötis, to compare their results with previously published literature on δ Boötis, and to use proper motion vectors to establish whether δ Boötis is a true binary or an optical double. During this project, the students learned how to gather original data on the double star δ Boötis, and mastered the techniques of telescope collimation and operation, calibration of an astrometric eyepiece, separation and position angle measurements, and data analysis. In comparison to previously published literature, the students found that the results of this study can be considered reasonably accurate due to the difference of less than 5% between the experimental data and the literature. Finally, by using proper motion vectors, the students learned to determine whether or not δ Boötis may be a true binary system. During this project, the students learned many skills essential to astrometric research. In their effort, the students faced many of the challenges common to astronomers including wind interference and reweighting the telescope to avoid backlash. They also calculated the scale constant for the astrometric eyepiece and conducted statistical analysis to verify the significance of their data. Finally, this project allowed students to communicate their original findings to the larger community both through writing a scientific paper and presenting their results to a large group of both students and teachers of astronomy. Acknowledgments We would like to thank Pine Mountain Observatory for allowing us to use its facilities; Russell Genet, Richard Berry, Tomas Frey, and Vera Wallen for their general assistance and facilitation; and William Lamb for providing us with the opportunity to attend this workshop. References Estrada, C.; Johnson, J.; Weise, E.; Fisher, J.; Howard, T.; Salam, A.; Almich, C.; Kessinger, D.; Cavanillas, S.; Matakovich, T.; Maly, K.; Wallen, V.; Genet, R. 2010,. 6, Frey, Thomas and Frey, A., 2010, Journal of Double Star Observations. 6, 2 4. Grocheva, E and Kiselev, A., 1998, ASP Conference Series. 145, Haas, Sissy. 2006, Double Stars for Telescop. Cambridge, MA: Sky Publishing, Johnson, Jolyon M. and Genet, R., 2007, Journal of Double Star Observations. 3, Johnson, Jolyon. 2008, Proceedings for the 27th Annual Conference of the Society for Astronomical Sciences Mason, Brian. 2010, The Washington Double Star Catalog. Astronomy Department, U.S. Naval Observatory. Tanguay, Ronald. 1998, The Double Star Observer s Handbook. Saugus, MA: Double Star Observer. Teague, Tom. 2004, Observing and Measuring Visual Double Stars. ed. Bob Argyle. London: Springer.

9 Page 9 Visual Measurements of a Selected Set of 20 Double Stars Kodiak Darling, Kristy Diaz, Arriz Lucas, Travis Santo, Douglas Walker Estrella Mountain Community College Avondale, Arizona Abstract: The observations and measurements for a selected set of twenty binary stars are reported. These tasks comprised the activities in a continuation of a special mathematics course devoted to research techniques being taught at the Estrella Mountain Community College in Avondale, Arizona. The fall 2010 semester focused on telescope operations, observations and measurements of a selected set of ten binary stars and an analysis of their proper motion. The spring 2011 semester extended the observational sessions and measurements to a set of an additional twenty binary stars. In addition, the comparison of a selected subset of measurements taken with a webcam was compared to visual observations. All observation were taken with a Meade 12 Schmidt Cassegrain Telescope (SCT) using the Celestron MicroGuide TM for measurements. Introduction and Instrumentation This observation program is part of a special mathematics class conducted during the fall 2010 and spring 2011 semesters at the Estrella Mountain Community College located in Avondale, Arizona. This mathematics course is designed to give students an introduction to performing real-world research with the end goal of collecting measurement data which is of sufficient quality to be of value to the scientific community. Measurement data collected during the fall 2010 semester has been published in the April 2011 edition of, Volume 7 Number 2. The approach and results for the spring 2011 semester observing sessions were presented at a conference talk at the 30 th Annual Conference on Telescope Science in Big Bear Lake, California conducted by the Society for Astronomical Sciences. The selection of researching binary stars was chosen since the observation and measurements of double star systems are an area which can be achieved with the use of small telescopes. The instrumentation used for observations and measurements consisted of a Meade 12 LX200GPS F/10 Schmidt-Cassegrain telescope. This system contained the GPS feature which made initial setup and calibration fast and easy. Visual double star measurements were obtained using the Celestron MicroGuide TM eyepiece which is a 12.5 mm F/L Orthoscopic with a reticule and variable LED. All observations were taken on the campus of Estrella Mountain Community College campus located at N, W during evening hours which generally consisted of between 6:00 and 9:00 PM local time (01:00 to 04:00 UT). Observations and measurements covered the dates from late February 2011 through early April Selection of Stars As in fall 2010, the selection of stars for observation and measurement were taken from the Washington Double Star Catalog (WDS). The WDS is maintained by the United States Naval Observatory and is the world's principal database of astrometric double and multiple star information containing positions (J2000), discoverer designations, epochs, position angles, separations, magnitudes, spectral types, proper motions and when available, Durchmus-

10 Page 10 Visual Measurements of a Selected Set of 20 Double Stars terung numbers and notes for the components of 108,581 star systems. The current version of the WDS is updated nightly. The initial approach in fall 2010 was to select a set of target stars from the neglected list on the WDS main web page. However, in the process of attempting actual measurement data it was determined that many of the stars on the original target list of neglected stars were beyond the observational capabilities of the observing site and the equipment. As results of these limitations, the original list was expanded to include a broader range of stars taken from the hour section of the WDS catalog website. The criteria for observations were modified to the following: Primary and companion being magnitude 9 or brighter At least one magnitude difference between the primary and companion Separation distance being greater than 5 and less than about 300 arcsecs This relaxed criteria list proved to be a nice combination of target stars in need of observation and available enough for the telescope equipment. This approach was duplicated for the spring 2011 semester with the list of target stars now occupying the sky from 5 to 9 hrs RA. Visual Measurements of Selected Binary Stars Duplicating the approach in fall 2010, the measurements of the separation distance and position angle of the selected target stars was accomplished using a standard visual observational approach. All measurements were acquired utilizing the Celestron MicroGuide TM. In order to produce high quality measurements, care was taken in calibrating the measurement instrument and performing a series of test measurements for validation of results before proceeding to the measurements of the target stars. MicroGuide Calibration Care was taken during fall 2010 to calibrate the Celestron MicroGuide TM in order to obtain the highest precision measurements. The technique for calibration was the standard star drift method with the process being carried out over several nights using all observers in order to minimize any observer and instrumentation bias. The approach consisted of locating a target star of sufficient visual magnitude as close to the zenith as possible. An observer centered the star along the microguide s linear axis and the telescope drive was temporary switched off to allow the star to drift down the linear scale. After an observer s timing measurement was acquired, the telescope s drive was reactivated and the star repositioned to begin another timing run. A different observer took the next timing measurement. This round-robin approach was applied to achieve a series of independent measurements for each observer. These measurements were then averaged to produce the calibration for this observing system. Calibration results for fall 2010 resulted in a mean measurement of seconds per drift. A histogram distribution of drift measurement points is shown in Figure 1. The process was repeated for spring 2011 which resulted in the histogram shown in Figure 2 with a mean drift time of seconds. A review of Figures 1 and 2 indicates a non Gaussian distribution of observation measurements were obtained in fall 2010 and a more symmetric Gaussian Frequency Seconds per Drift Figure 1: Histogram of Calibration Measurements Fall 2010 Frequency Seconds per Drift Figure 2: Histogram of Calibration Measurements Spring

11 Page 11 Visual Measurements of a Selected Set of 20 Double Stars Table 1: Summary Results for MicroGuide TM Calibration Period Average 1 STD Fall Spring type distribution obtained in spring The mean and the one standard deviation for both calibration runs are shown in Table 1. Using the standard calibration formula for the MicroGuide resulted in a value of 7.26 arcsecs per MicroGuide grid interval for the fall 2010 measurements and 7.39 arcsecs per grid interval for spring The difference was attributed to equipment calibrations during the time intervals. Measurements Process A round robin technique used for taking new measurement data was utilized repeating the process used in fall Separation was measured by orienting the selected systems along the Microguide s linear scale, and noting their separation as indicated by the scale s tick marks. Position angle was then measured by aligning the binary systems along the linear scale, with the primary star directly on mark 30, and the secondary along the scale between marks 30 and 60. After the stars were aligned, the telescope s tracking system was temporarily disabled, allowing the binary system to drift out of the eyepiece s field of view. The binary system crossed over the circular scale which runs along the edge of the telescope s FOV, as this happened the position of the secondary star along this circular scale was noted. 90 degrees were then added or subtracted from this measurement, depending upon orientation, to achieve our final Position Angle measurements. These processes were repeated several times per system for separation accuracy. Summary of measurement data are shown in Table 2. Table 2: Summary Data for Measures 2011 WDS ID Discover. Magnitudes Last Current Primary Sec Epoch PA SEP Epoch PA SEP HJ 460AC S 513AD JC 10AB STU 22AB-D STU 23AC HJ 3834AC ARN 2AC DUN 38AC HJL1046AB ARN 66AF ENG 37AB S 529AC STF1088AE S 563AB HJ 3858AB DUN 72AB KNT 4AB JC 10BC STTA STTA 84AB

12 Page 12 Visual Measurements of a Selected Set of 20 Double Stars Figure 3: Imagery for S529 AC Figure 4: Imagery for STF1088A Video Imagery of Selected Stars Toward the end of the visual star observing program, a Phillips 900NC video web camera was used to investigate capturing imagery of a selected set of the binary stars. The primary objective of the experiment was to determine the capabilities of low cost web cameras for use in obtaining high precision measurements of double stars. A second objective was to determine whether a web camera could obtain imagery of doubles with fainter magnitudes than would be observable with visual means. During an observing session conducted over successive nights, 8 binary star pairs were captured. Several examples are described in detail. Binary S529 AC primary is magnitude 6.91 with a secondary at magnitude See Figure 3. The last measurement in the WDS database indicated a separation of arc-seconds and position angle of 160 degrees. The epoch was Binary STF1088A primary is magnitude 7.38 with a secondary at magnitude 8.1. See Figure 4. The last measurement in the WDS database indicated a separation of arc-seconds and position angle of 224 degrees with an epoch of Binary STTA84AB (Figure 5) has a primary at magnitude 7.72 with a secondary at magnitude The WDS database indicates a separation of arc -seconds and position angle of 324 degrees with an epoch of Overall, 8 stars were successfully imaged with magnitudes ranging from 6.4 up to Imaging of Figure 5: Imagery for STTA84AB fainter stars was not possible with direct video capture. Preliminary analysis utilizing stacking techniques was attempted but none were successful. Additional work needs to be performed in this area. Analysis of Separation using REDUC REDUC is a software package dedicated to double stars measurements. The latest version can be downloaded free on simple demand. It is perfectly adapted to performing measurements on imagery captured with simple CCD and video cameras as demonstrated here. The main window shown in Figure 6 (Continued on page 14)

13 Page 13 Visual Measurements of a Selected Set of 20 Double Stars Figure 6: REDUC Main Window Table 3: Comparison of Visual and Imaged Separation in Arc-seconds Separation (as) Star WDS Observed Imaged % Accuracy to WDS STTA 84AB STF1088AE

14 Page 14 Visual Measurements of a Selected Set of 20 Double Stars (Continued from page 12) provides the ability to load AVI files, select specific targets and then performs accurate measurements once it is calibrated. To provide test data on the utilization of REDUC, star pair S 529AC was loaded and use as a calibration set. This was applied to star pairs STTA 84AB and STF1088AE with results shown in Table 3. This limited test shows the promise of using inexpensive video imaging equipment for stars brighter than about magnitude 9. Additional image processing techniques could be applied to image fainter stars but to what magnitude limit would be obtainable is currently unknown. Conclusion These observations provide additional information for researchers to investigate the nature of binary systems. Acknowledgments We would to thank Becky Baranowski, Department Chair for Mathematics, Physics, and Astronomy for offering this course for the year 2010/2011 and to the Estrella Mountain Community College for use of equipment and facilities. References 1. Ronald Charles Tanguay, Observing Double Stars for Fun and Science 2. Argyle, Bob, Observing and Measuring Visual Double Stars, Springer-Verlag London Limited Sky and Telescope Magazine, March The Celestron Micro Guide Eyepiece Manual (#94171)

15 Page 15 Double Star Measurements at the Internationale Amateur Sternwarte (IAS) in Namibia in 2009 Rainer Anton Altenholz/Kiel, Germany rainer.anton"at"ki.comcity.de Abstract: This paper is a continuation of earlier work published in JDSO in Using a 40-cm-Cassegrain telescope in Namibia and a fast CCD camera, 87 double and multiple systems were recorded and analyzed with the technique of lucky imaging. Measurements are compared with literature data. Some noteworthy systems are discussed in more detail. Introduction During two weeks in September 2009, I used the 40-cm-Cassegrain at the Internationale Amateur Sternwarte (IAS) in Namibia for observing double stars in the southern sky [1]. Some measurements have already been published earlier in this Journal [2]. Results for 87 more systems obtained during this period are presented here. The technique of lucky imaging for recording and measuring double stars is well known, and details have been described in earlier papers [2,3]. With lucky imaging, seeing effects can be drastically reduced, and the resolution can be pushed to the theoretical limit of the telescope. The accuracy of position measurements can even be one order of magnitude better than this. With a 40-cm telescope, standard deviations of separation measurements of close pairs of the order of ±0.05 were obtained. Most of the 87 investigated systems are well known, with brightness down to the range of ninth magnitude, with only a few dimmer ones. Thirty are binaries with more or less well documented orbits. However, in many cases literature data are scarce, such that estimates of residuals are somewhat ambiguous. For some systems, deviations from predicted movements could be manifested. Systems, for which sufficient and trustworthy literature data exist, are used for calibration of the image scale. Instrumental The nominal focal length of the 40-cm Cassegrain is 6.3 m. With my b/w-ccd camera (DMK21AF04, pixel size 5.6 µm square, The Imaging Source), an image scale of /pixel was determined from measurements of reference systems, as described earlier. When using a 2x-Barlow lens, the scale was /pix. Almost always, a red filter was used to reduce seeing effects, as well as the chromatic aberration of the Barlow lens. Exposure times were from 0.5 µsec up to 0.1 sec, depending on the star brightness and the seeing. From recordings of some thousands of frames, I usually select the best ones by visual inspection with the program VirtualDub. The typical yield is about 50 to 150 frames, which are re-sampled and aligned with the program Registax, often with the option manual, and finally automatically stacked. Calibration and Measurements As described in earlier papers, the image scale is determined by measuring a number of doubles with well known separations. All systems are suitable, for which literature data can unambiguously be extrapolated to the actual date. Main sources are the WDS [4], and the 4 th Catalog of Interferometric Measurements of Binary Stars [5]. Results for binaries are also compared with data from the Sixth Catalog of Orbits of Visual Binary Stars [6]. 22 systems were

16 Page 16 Double Star Measurements at the Internationale Amateur Sternwarte (IAS) in Namibia in 2009 found suitable as reference. In the table below, these are marked with shaded lines. The scale factors cited above were essentially the same as obtained in earlier work with the 40-cm telescope, with standard deviation of about ±0.05. While the accuracy of separation measurements is constant, the contribution of the scale factor lets the total error margin increase for greater separations to up to ±1.0%. The position angle was deduced from recordings of star trails with the telescope drive switched off, so as to reveal the actual east-west-direction in the field of view. The error margin depends on the separation, and ranges from ±0.1 o for wide pairs up to almost ±4 o for close ones near the resolution limit. All measurements are listed in Table 1, and the scatter of the residuals is illustrated in Figures 1 and 2 (see below). Comments Most of the 87 systems presented here are fairly bright and easily accessible with not too small telescopes, which also means suitable for lucky imaging. Nevertheless, many of them can be deemed as neglected, as there are only few data in the literature. More attention is generally paid to binaries with not too long periods, for obvious reasons. Twenty-two systems were found, for which extrapolations of literature data of separations appear sufficiently accurate, such that they can be taken for reference. The standard deviation of the resulting residuals of about ±0.05, calculated versus the thus determined calibration constant, contains both contributions from errors of own measurements, as well as of literature data, as is the case for the residuals of all other pairs. As was already mentioned above, the total, absolute error margin increases with separation, due to the contribution of the calibration factor with constant relative error of ±1.0 %. Some pairs were found noteworthy, be it because of large residuals, which are marked in Figure 2, or for other reasons. - The pair ε Sculptoris (HJ3461 AB, #12) seems to be physical. A premature orbit has been published in 1974, but positions strongly deviate, in accordance with the trend of literature data. - The multiple θ 1 Orionis, the trapezium (STF 748, #30), although prominent, has not often been measured. Literature data of separations, both visual and speckle, exhibit large scatter and residuals are somewhat ambiguous. In contrast, residuals for P.A. are all within the error limits. (Continued on page 23) Figure 1: Plot of the residuals of the position angle versus separation rho. Note semi-logarithmic scaling. Full rhombs indicate 22 pairs used for calibration, open rhombs all others. Open squares refer to the system θ 1 Orionis, the "trapezium". The increase of scatter towards small separations is due to the fixed image resolution. The standard deviation for only the calibration systems is ±0.53 o. Figure 2: Plot of the residuals delta rho versus rho. Note semi-logarithmic scaling. Full circles indicate pairs used for calibration, open circles all others. Three of them with residuals exceeding the error limits are marked with their note numbers. Open squares refer to the system θ 1 Orionis, the trapezium. The standard deviation for only the calibration systems is ±0.047" with range between 0.08" and +0.10". The curves indicate the total, absolute error margins.

17 Page 17 Double Star Measurements at the Internationale Amateur Sternwarte (IAS) in Namibia in 2009 Table 1: List of measurements. Systems used for calibration are marked with shaded lines. System names, positions and magnitudes are taken from the WDS. The two columns before the last one show the differences delta of measured position angles (P.A.) and separations (rho) minus reference data. For several pairs, no residuals are given because of insufficient reference data. N is the number of measurements at different nights, or with different camera settings or filters. Individual notes are following the table. Asterisks denote systems of which images are shown in the figures. PAIR RA + DEC MAGS P.A. meas. rho meas. DATE N delta P.A. delta rho BU 391AB BU HDO DUN HJ 3416AB NOTES RST1205AB RMK 2AB-C ~0 6 BU STF 113A-BC ~ HJ ~ HJ DUN HJ 3461AB ~ HJ ~0 ~0 13 STF * H BU HJ ~0 ~0 17 BU 741AB S 723AC * HJ DUN DUN STF 470AB * BU ~0 ~0 23 HJ ~ STF DUN 18AB STT ~ STT 517AB ~ * STF Table continued on next page.

18 Page 18 Double Star Measurements at the Internationale Amateur Sternwarte (IAS) in Namibia in 2009 Table 1 continued: List of measurements. Systems used for calibration are marked with shaded lines. System names, positions and magnitudes are taken from the WDS. The two columns before the last one show the differences delta of measured position angles (P.A.) and separations (rho) minus reference data. For several pairs, no residuals are given because of insufficient reference data. N is the number of measurements at different nights, or with different camera settings or filters. Individual notes are following the table. Asterisks denote systems of which images are shown in the figures. PAIR RA + DEC MAGS STF 748AB P.A. meas. rho meas. DATE N delta P.A. delta rho STF 748AC ~ STF 748AD STF 748AE STF 748BC STF 748BD STF 748CD STF 748CF AGC 1AB I 10AB ~ RHD 1AB SHJ 243AB BSO 13AB ~ STF2262AB STF2272AB H DUN BSO 14AB HJ HJ ~ GLE DUN SCJ S HJ 599AB * HJ 599AC DUN STF ~0 49 HDO RMK DUN ~0 52 SHJ 323 AB SHJ NOTES 30 Table continued on next page.

19 Page 19 Double Star Measurements at the Internationale Amateur Sternwarte (IAS) in Namibia in 2009 Table 1 conclusion: List of measurements. Systems used for calibration are marked with shaded lines. System names, positions and magnitudes are taken from the WDS. The two columns before the last one show the differences delta of measured position angles (P.A.) and separations (rho) minus reference data. For several pairs, no residuals are given because of insufficient reference data. N is the number of measurements at different nights, or with different camera settings or filters. Individual notes are following the table. Asterisks denote systems of which images are shown in the figures. PAIR RA + DEC MAGS P.A. meas. rho meas. DATE N delta P.A. delta rho HU 200AB S 763AB STF2729AB RMK HJ H HJ * BU ~ BU 766AB ? 0.18? BU 1212AB HDO 296AB BU ~0 ~0 66 H N 56AB I ~ BU 172AB ~0 69* PZ 7AC DUN BU JC 20AB DUN HU STF DUN I B I * SEE * DUN ~0 82 HU H ~ SLR * LAL LAL ~ NOTES

20 Page 20 Double Star Measurements at the Internationale Amateur Sternwarte (IAS) in Namibia in 2009 Notes: Terms cpm (common proper motion) and relfix (relatively fixed) refer to Burnham [7]. 1. κ Sculptoris, PA decreasing. 2. in Cetus, binary, P=25y. 3. λ Sculptoris, PA increasing. 4. in Tucana, although only few data, extrapolation seems fairly trustworthy, PA slowly increasing, rho slowly decreasing. 5. in Tucana, although deemed relfix, rho is slowly increasing. 6. ζ Phoenicis, AB binary, P=210y, PA fast inc. Few data for AC. 7. in Sculptor, probably binary, PA and rho dec Ceti, PA inc. 9. in Cetus, probably binary, PA dec, rho inc. 10. τ Sculptoris, binary, P=1876y. 11. p Eridani, binary, P=484y. 12. ε Sculptoris, binary, a premature orbit has been calculated in 1969, few data. While PA close to ephemeris, and decreasing, rho deviates markedly. 13. in Hydrus, few data, but small scatter, PA inc. 14. in Cetus, binary, P=162y, many speckle data, see Figure in Cetus, few data, but relatively small scatter, PA dec, rho inc. 16. in Fornax, binary, P=305y, orbit highly inclined. 17. ω Fornacis, relfix, cpm. 18. in Fornax, AB binary, P=137y, orbit highly inclined, newly computed in Few data for AC, no residuals given. PA and rho inc. See also Figure α Fornacis, binary, P=314y, orbit highly inclined, few data. 20. in Eridanus, few data. 21. f Eridani, few data, but small scatter, PA and rho inc Eridani, rho fairly constant, nice color contrast, see Figure in Eridanus, PA slow dec, rho inc. 24. in Dorado, binary, P=240y, residuals given versus recently revised ephemeris, orbit highly inclined. Figure 3: Some sub-arcsecond doubles. Except for I 25, the physical nature of the others is well documented with orbit calculations. See also notes # 69, 81, 28, 80, 14, and 85 (in rows from top to bottom) Eridani, cpm, while deemed relfix, large scatter of rho data, residuals given versus average of last entries in speckle catalog of 1991 and 2004, PA inc. 26. ι Pictoris, few data with large scatter, rho inc? Orionis, binary, P=199y, many speckle data. 28. in Orion, binary, P=312y, many speckle data, see Fig Orionis, binary, P=586y, many speckle data. 30. θ 1 Orionis, trapezium, relatively large differences of mainly rho measurements compared

21 Page 21 Double Star Measurements at the Internationale Amateur Sternwarte (IAS) in Namibia in 2009 with last entries in the speckle catalog from 2002 to 2008, reason unknown. 31. α Canis Majoris, Sirius, binary, P=50.1y, residuals vs. ephemeris. 32. δ Velorum, binary, P=142y, difficult, because dim companion on diffraction ring, residuals vs. ephemeris. 33. α Centauri, binary, P=79.9y, residuals vs. ephemeris Ophiuchi, binary, premature orbit, P=550y. 35. in Ara, also known as L7194, binary, P=693y, few data, recent measurements tend to deviate from calculated orbit. 36. τ Ophiuchi, binary, P=280y, many speckle data, residuals given vs. trend Ophiuchi, binary, P=88.3y, many speckle data with small scatter. 38. in Corona Australis, binary, P=191y, residuals vs. ephemeris. 39. κ Coronae Australis, relfix, few data with large scatter, residual of rho ambiguous. 40. in Corona Australis, large scatter of literature data, no residuals given. 41. in Pavo, few data. 42. γ Coronae Australis, binary, P=122y, PA dec. 43. in Pavo, binary, P=157y. 44. β Sagittarii, large scatter of literature data. 45. in Sagittarius, also know as BU 142, binary, P=162y, many speckle data with relatively small scatter. Residuals given vs. speckle data of about the same epoch. 46. in Sagittarius, few data with large scatter Sagittarii, no recent literature data of AB, large scatter of data for AC, no residuals given. Dim companion of about 13 th magnitude at o /56.8 not listed in the WDS. See Figure in Telescopium, cpm, few data, PA dec, rho slow inc Aquilae, relfix. 50. in Pavo. 51. in Pavo. 52. in Sagittarius, PA inc, rho almost fixed. 53. rho Capricorni, binary, P=278y, orbit highly inclined, own measurements, as well as literature data seem to deviate from ephemeris, Figure 4: The triple system BU 741 AB/S 723 AC in Fornax. The pair AB is a physical binary with period 137 y. See also note 18. Figure 5: The multiple HJ 599 or 54 Sagittarii. The seeing allowed for 2 sec exposure, superposition of 40 frames. The dim companion at upper left, which is marked with black lines, is not listed in the WDS. See also note 47.

22 Page 22 Double Star Measurements at the Internationale Amateur Sternwarte (IAS) in Namibia in 2009 residuals given vs. ephemeris. 54. ο Capricorni. 55. τ Capricorni, binary, P=200y, peculiar scatter of literature (speckle) data, residuals given vs. ephemeris. 56. in Capricornus, relfix Aquarii, binary, P=187y, recent rho data seem to deviate from ephemeris, residuals given vs. ephemeris. 58. in Pavo, also known as L8550, cpm, PA dec. 59. in Capricornus, PA fast, rho slowly dec. 60. in Capricornus, probably binary, ephemeris questionable, residuals vs. speckle data from θ Indi, cpm, PA slow dec?, rho fast inc, nice color contrast, see Fig in Capricornus, PA and rho dec in Microscopium, not resolved here, but elongated, PA and rho estimated, both are decreasing, residuals vs. trend of literature data, last entry in speckle catalog from Aquarii, binary, P=49y, many speckle data with small scatter. 65. in Indus, binary, P=27.5y, orbit highly inclined, few data. 66. η Piscis Austrini, relfix, PA dec Aquarii, few data with large scatter, especially for rho, PA dec, color contrast. 68. in Tucana, binary, P=983y, PA decreasing, rho slowly inc, residuals estimated vs. trend Aquarii, binary, P=146y, residuals vs. speckle data from β Piscis Austrinus, cpm, relfix, few data with large scatter, no residuals given. 71. in Piscis Austrinus, optical, few data, rho seems to linearly increase. 72. υ Gruis, few data, PA and rho decreasing, some earlier speckle data show peculiar scatter, residuals vs. trend. 73. θ Gruis, cpm, both PA and rho seem to linearly increase. 74. in Grus, PA slowly decreasing, rho inc Aquarii, binary, P=63y, residuals vs. ephemeris. 76. in Aquarius, optical, residuals vs. rectilinear extrapolation. 77. in Grus, few data. 78. in Phoenix, PA inc, few data. 79. in Aquarius, few data with large scatter, no residuals given. 80. in Phoenix, PA dec. 81. in Sculptor, binary, P=78y, difficult, because dim companion is close to diffraction ring of main star, not resolved with speckle interferometry in 2008, PA fast inc. 82. θ Phoenicis, PA increasing, rho slowly decreasing? 83. in Phoenix, few data with large scatter, PA and rho increasing? Aquarii, rho slow inc? 85. in Phoenix, binary, P=117y, PA fast dec, rho fast inc. Figure 6: Two colorful doubles: Left: 32 Eridanis, spectra are G8III and A2V. Description of colors in the literature range from grapefruit-orange and silvery-blue to topaz-yellow and sea green. Right: theta Indi. A not so frequent case of a red companion to a main sequence star. Spectral class of the latter is A5V, that of the companion is not listed. Colors are described in the literature as light-yellow and reddish-brown. See also notes 22 and φ Sculptoris, also known as DUN 253, relfix. 87. also known as Arg 46, few data, PA and rho slowly dec.

23 Page 23 Double Star Measurements at the Internationale Amateur Sternwarte (IAS) in Namibia in 2009 (Continued from page 16) - For the binary BSO 13/L 7194 in Ara (#35), with period of about 700 years, only few data are available in the literature. Recent measurements of the separation tend to deviate from the ephemeris from The binary rho Capricorni (SHJ 323 AB, #53) exhibits a highly inclined orbit. Both own measurements and literature data tend to deviate from the currently assumed ephemeris. - The close pair 4 Aquarii (STF 2729 AB, #57) is a binary with period 187 years. Separation measures tend to be greater than expected from the ephemeris by about 0.05, in accordance with literature data. - Residuals for the pair H I 47 in Capricornus (#60) are within the error limits, when referred to recent speckle data, but strongly deviate from the ephemeris published in With an estimated period of more than 4000 years, this seems to be in error. References [1] IAS, [2] Anton, R., 2010,, vol. 6 (2), [3] Anton, R., 2009,, vol. 5 (1), [4] Mason, B.D. et al., The Washington Double Star Catalog (WDS), U.S. Naval Observatory, online access July [5] Hartkopf, W.I. et al., Fourth Catalog of Interferometric Measurements of Binary Stars, U.S. Naval Observatory, online access July [6] Hartkopf, W.I. et al., Sixth Catalog of Orbits of Visual Binary Stars, U.S. Naval Observatory, online access July [7] Burnham s Celestial Handbook, R. Burnham, Jr., Dover Publications, New York 1978.

24 Page 24 Chico High School Students' Astrometric Observations of the Visual Double Star STF 1657 Jonelle Ahiligwo 1, Clara Bergamini 1, Kallan Berglund 1, Mohit Bhardwaj 1, Spud Chelson 1, Amanda Costa 1, Ashley Epis 1, Azure Grant 1, Courtney Osteen 1, Skyla Reiner 1, Adam Rose 1, Emily Schmidt 1, Forest Sears 1, Maddie Sullivan-Hames 1, and Jolyon Johnson 2 1. Chico Senior High School, California 2. Gateway Science Museum, California State University, Chico Abstract: In the spring of 2011, Chico Senior High School students participated in an astronomy seminar at the Gateway Science Museum, University of California, Chico. The observers used a Celestron NexStar 6 SE telescope and a Celestron MicroGuide eyepiece to determine the separation and position angle of the visual double star STF Observations were made in approximately one hour on the evening of May 1, The observers determined that the separation of STF 1657 was 22.1 and the position angle was Seminar members then used the spectral type, parallax, and proper motion vectors of the two stars to determine if they are a line-of-sight optical pair or physically bound by gravity. Due to large errors in the parallax and the proper motion vector for the secondary star, the results were inconclusive. Through this experience, the students learned the skills needed to observe, analyze, and report on double stars. Introduction In the spring of 2011 Jolyon Johnson led an astronomy research seminar of fourteen enthusiastic students from Chico Senior High School, California. The seminar was offered through the Gateway Science Museum at California State University, Chico, and focused on the study of visual double stars. It followed a model developed at Cuesta College in San Luis Obispo, California and the University of Oregon's Pine Mountain Observatory (Johnson 2007, Genet et al. 2010a, Genet et al. 2010b). The goals of the seminar were both scientific and educational. The scientific goals were to: 1) contribute observations to the Washington Double Star (WDS) catalog, and 2) determine whether or not this double star is likely a chance optical line-of-sight Figure 1: Students gathered at the Gateway Science Museum on the evening of May 1, 2011 to observe the double star STF 1657 with a Celestron NexStar 6 SE telescope and a Celestron MicroGuide eyepiece.

25 Page 25 Chico High School Students' Astrometric Observations of the Visual Double Star STF 1657 double or a binary star bound by gravity. The educational goals were to: 1) gain a better understanding of astronomy through hands-on experience, 2) learn and apply a method for measuring the separation and position angle of a double star, and 3) learn the process for analyzing data and writing and editing a scientific paper. Methods The students searched the WDS catalog to identify observable stars based on their magnitude and separation. The stars had to be bright enough and far enough apart to observe in a 6-inch telescope and bright city skies. The visual double star STF 1657 fit the criteria with a primary magnitude of 5.1, a secondary magnitude of 6.3, and separation of 19.9 arc seconds (Mason 2008). Observations were made on May 1, 2011 (B ) with a Celestron NexStar 6 SE telescope and a 12.5 mm illuminated Celestron Micro Guide eyepiece. Several past seminars have used the same telescope and eyepiece as the present study to observe double stars. The scale constants they derived were averaged and used in the present study. Table 1 shows the three scale constants used, their average, standard deviation, and standard error of the mean. The mean error of 0.1 /div is significantly less than the mean observational error. The separation of the two stars was estimated to the nearest 0.1 division on the linear scale (Teague 2004). Each student noted at least one observation and whispered it to a designated recorder so others could not hear, thus preventing bias. A total of 12 measurements were made. Three outliers were excluded from the mean because they were more than three times the standard deviation from the average. These outliers were due to the stars drifting away from the linear scale because of polar misalignment. The mean distance in divisions was multiplied by the scale constant of 12.3 arc seconds per division to convert the measured value into arc seconds. The students then calculated the standard deviation and standard error of the mean of this separation. The drift method was used to measure the position angle between celestial north and the secondary star with the primary star at the vertex (Teague 2004). First the primary star was centered at the midpoint of the linear scale and the eyepiece was rotated until the secondary star was between the parallel lines of the scale. The RA motor was then disabled and the stars drifted toward the outer protractor. Where the primary star crossed the protractor was noted to the nearest degree and secretly told to the recorder to avoid bias. A 90 position angle correction was added to the measurements as is required for the Celestron MicroGuide eyepiece (Teague 2004). A total of 10 measurements were made and their average, standard deviation, and standard error of the mean were calculated with one outlier rejected because it was more than three times the standard deviation. The outlier was precisely 20 off and likely the result of misreading major divisions. Observational Results Table 2 shows the results of the separation and position angle measurements including the averages, standard deviations, standard errors of the mean, and the average of three catalog values, the first and last from the WDS Catalog and one from Eagle Creek Observatory (Mason 2008 and Muenzler 2003). The difference between the observed and average catalog separation value of 1.8 is higher than would be expected four times the standard error of the Table 1: The measured scale constants of past research seminars using the NextStar 6 SE and Celestron Microguide eyepiece used in the present study. Scale constant (arc seconds per division) Baxter et al Brashear et al. 2011a 12.5 Brashear et al. 2011b 12.2 Average 12.3 Table 2: The averages, standard deviations, and standard errors of the mean for the separation and position angle compared to catalog values. Separation Position Angle Observed Catalog Observed Catalog Average St. Dev Mean Err St. Dev. 0.2 Mean Err. 0.1

26 Page 26 Chico High School Students' Astrometric Observations of the Visual Double Star STF 1657 mean of 0.4. The maximum for the catalog values is still 0.2 different from the minimum observed value. If the minimum scale constant of 12.2 /div is used, the average separation is This is still four times the standard error of the mean away from the average of catalog values. The authors attribute the difference primarily to polar misalignment (which caused the stars to drift away from the linear scale) or other systematic errors. The observed position angle was also significantly different from the average catalog value. The difference of 1.4 is 7 times the standard error of the mean of 0.2. However, there is overlap between the maximum catalog values and minimum observed value. The difference may have been caused by an imprecise alignment of the stars on the linear scale. System Analysis The students referenced the SIMBAD (2011) database to determine whether or not the stars could be a gravitationally bound binary. The pair of stars selected has the WDS designation of STF 1657, which corresponds to HD and HD for the primary and secondary stars, respectively. To determine if it is possible that the two stars are bound by gravity, we first compared the spectral types and apparent magnitudes of the two stars. The primary star is spectral type K2III and has a primary magnitude of 5.11, making it likely to be a red giant. The secondary star is on the main sequence with spectral type A9V at magnitude It is difficult to estimate how bright a red giant should be compared to an intrinsically bright main sequence star, so a more quantitative analysis had to be made. The group then attempted to calculate the actual distance to the two stars from Earth based on their respective trigonometric parallaxes. The distance in light years can be calculated as the inverse of the parallax in arc seconds multiplied by 3.26 (the number of light years in one parsec). The parallax of the primary star is arc seconds which corresponds to a distance of 614 light years. The parallax of the secondary star is arc seconds which corresponds to a distance of 2,629 light years. While this would certainly suggest the stars are not bound by gravity, the error statement of the secondary star's parallax is arc seconds. The secondary star could be infinitely far away (since there cannot be a negative parallax the minimum value is 0.0 arc seconds) or as close as 292 light years. This range of values makes the calculated distance unreliable. Therefore, we could not use the distance estimates to determine the likelihood that the stars are bound by gravity. Finally, the students analyzed the proper motion vectors of the two stars to determine if they are traveling through space in approximately the same direction. Most binary star components have proper motion vectors within 10% of each other (Arnold 2010). Table 3 shows the proper motion vectors of the two stars of STF While the vectors appear different, the errors for the secondary star are very large, milliarcseconds per year (mas/yr) in RA and mas/yr in dec. Thus the secondary star could be traveling as slow as mas/yr in RA and as high as mas/ yr in dec. Additionally, the error in RA for the primary star is 2.12 mas/yr giving a maximum value of mas/yr. With the errors taken into account, the two stars can be shown to travel essentially in the same direction through space. Yet, this can only be done with the extremes of the uncertainties, making it possible, though unlikely, that the stars are moving in the same direction. Table 3: Proper motion vectors for the primary and secondary stars RA (mas/yr) Dec (mas/yr) HD HD Conclusions Due to the large error margins reported for the trigonometric parallax and proper motion vectors in the SIMBAD database for HD , it is uncertain whether or not the system is bound by gravity. More precise parallax and proper motion vectors may help determine if the stars do, in fact, orbit one another. If this is proven, continued research may yield the semimajor axis, orbital period, and stellar masses. Though it could not be determined if the system was binary, the seminar proved a valuable learning experience. The students also learned some frustrations associated with astronomical observing. For example, the prime observing time happened to be the evening before a full moon so a new observing night had to be scheduled. This second evening was found to be cloudy in local weather forecasts. Thus, the observing night had to be on a school night in May when astronomical twilight did not occur until approximately 9:00 and everyone had to leave by 10:00. Observations

27 Page 27 Chico High School Students' Astrometric Observations of the Visual Double Star STF 1657 had to be limited to just the double star unlike previous seminars that also determined the scale constant for the linear scale. Once sufficient separation and position angle measurements were taken, observing time was over. The students are hopeful that the separation and position angle values they determined may be added to the WDS catalog and used by future researchers if STF 1657 proves to be binary. On the evening of observations, the students learned how to polar align the NexStar 6 SE, apply the astrometric vocabulary they learned during the seminar, and avoid potential research biases. The following meetings taught students how to turn simple measurements into meaningful data by using basic statistics. Finally, the students learned the tools astronomers use to identify binary stars and compiled the information into a research paper. Such skills are invaluable to high school and undergraduate students headed for careers in science. Acknowledgments The authors would like to thank the Gateway Science Museum at California State University, Chico and Director Rachel Teasdale for hosting the seminar. The students also thank Russ Genet at California Polytechnic State University for advising the seminar, loaning the telescope used in the project, and for reviewing the paper. The authors would also like to thank Celestron who donated the eyepiece, equatorial wedge, and tripod to student research. The authors finally thank Dave Arnold and Tom Frey for their helpful reviews. References Arnold, Dave, 2010, Considering Proper Motion in the Analysis of Visual Double Star Observations in Small Telescopes and Astronomical Research. Eds. Russ Genet, Jolyon Johnson, and Vera Wallen, Santa Margarita, CA: Collins Foundation Press. Baxter, Alexandra, et al., 2011, Comparison of Two Methods of Determining the Position Angle of the Visual Double Star 61 Cygni with a Celestron Micro Guide Eyepiece,, 7, 212. Brashear, Nicholas, et al., 2011a, Measurements and Analysis of the Visual Double Star STF 1919 at the 2010 Oregon Star Party. Journal of Double Star Observations, Submitted. Brashear, Nicholas, et al., 2011b, Observations, Analysis, and Orbital Calculation of the Visual Double Star STTA 123 AB. Journal of Double Star Observations, Submitted. Genet, Russell, et al, 2010a, One-Semester Astronomical Research Seminars in Small Telescopes and Astronomical Research, Eds. Russ Genet, Jolyon Johnson, and Vera Wallen, Santa Margarita, CA, Collins Foundation Press. Genet, Russell, et al, 2010b, Pine Mountain Observatory Summer Research Workshop in Small Telescopes and Astronomical Research, Eds. Russ Genet, Jolyon Johnson, and Vera Wallen. Santa Margarita, CA, Collins Foundation Press. Johnson, Jolyon, 2008, Double Star Research as a Form of Education for Community College and High School Students in Proceedings for the 27 th Annual Conference for the Society for Astronomical Sciences, Eds. Brian Warner, Jerry Foote, David Kenyon, and Dale Mais. Mason, Brian, 2011, The Washington Double Star Catalog, Astrometry Department, U.S. Naval Observatory. Muenzler, Kevin, 2003, Double Stars in Coma Berenices., Eagle Creek Observatory. com.html. SIMBAD Astronomical Database, 2011, Centre de Données Astronomiques de Strasbourg, simbad.u-strasbg.fr/simbad/. Teague, Tom, 2004, Simple Techniques of Measurement in Observing and Measuring Visual Double Stars, Ed. Bob Argyle. London, Springer. Jonelle Ahiligwo, Clara Bergamini, Kallan Berglund, Mohit Bhardwaj, Spud Chelson, Amanda Costa, Ashley Epis, Azure Grant, Courtney Osteen, Skyla Reiner, Adam Rose, Emily Schmidt, Forest Sears, and Maddie Sullivan-Hames are physics students at Chico Senior High School. Jolyon Johnson is a senior geology major at California State University, Chico. He is a docent at the Gateway Science Museum and led the spring astronomy seminar.

28 Page 28 A New Companion for STF 2590, WDS Micello Giuseppe Bologna Emilia Romagna, Italy 7mg8@libero.it Abstract: A new companion in Struve 2590 (WDS STF 2590) is described. This is a multiple star in the constellation Aquila and is composed of four components. The new component, identified in CCD images, is not present in the WDS. Introduction On August 12, 2011 I ran some footage CCD to make some routine astrometric measurements of double stars in the W. Struve catalog. Consulting the Washington Double Star Catalog, I noticed that STF 2590 (WDS , R.A ; DEC ) has four components, but the CCD images show a new component E (Mv 13.5) for this multiple star system. Methods For STF 2590, as shown in Table 1, the Washington Double Star Catalog (WDS) lists the measures for the AB, AC and CD pairs, but no measurement for an E component. CCD images, however, show a star near the B component of this multiple star system. The Aladin Sky Atlas (catalogs "SDSS-DR7, PPMXL, NOMAD1 e 2MASS-PSC") and the 2MASS- PSC indicate that this star is with a visual magnitude of The latest measures of the Washington Double Star Catalog were made in 2000 for the pair AC and in 2007 for pairs AB and CD. I consulted the articles published in the Journal of Double star Observations ( and found that Edgardo Rubén Masa Martin, in 2007, performed astrometric measurements for the AB and CD pairs [Masa Martin, 2009]. In note 96, in the same article, Masa states that component A is a variable star. Figure 1 shows an image of STF 2590 with the E component, obtained with Schmidt-Cassegrain telescope 200/2000. Astrometric Measurements and Data Analysis The astrometric measurements were performed with the software REDUC (By Florent Losse) and the calibration star used was STF 2777 (WDS STF 2777; Theta: 6 - Rho: 74,1 ). The telescope used was a Schmidt-Cassegarin 200/2000 on German equatorial mount and the optical train was composed of CCD Camera DMK 21AU with IR/UV cut filter.

29 Page 29 A New Companion for STF 2590, WDS Table 1: Astrometric measurements of STF 2590 from the WDS Name ID WDS Theta Rho Mv1 Mv2 Epoch Coordinate WDS R.A. DEC. STF 2590 AB STF 2590 AC STF 2590 CD " Figure 1: Image of STF 2590 showing the E component. Image by the author. As shown in Table 2, I updated the measurements for the pairs AB, AC and CD and performed, for the first time, the measurements for the pair AE: Theta: = and Rho = The catalog 2MASS-PSC catalog gives the quality flag "AAA", indicating the best quality JHK magnitudes which are: J - H - K = and a visual magnitude of Unfortunately, no proper motion for this star is reported in the 2MASS- PSC, NOMAD1 and PPMXL catalogs. The SDSS-DR7 catalog, indicates the component E as: class 6 = Star: A a self-luminous gaseous celestial body. Figure 2 gives the astrometric data from the SDSS (Sloan Digital Sky Survey - cas.sdss.org/astro/en/tools/explore/). (Continued on page 31)

30 Page 30 A New Companion for STF 2590, WDS Table 2: New astrometric measurements of STF 2590 AB, AC, and CD. First measurements new pair AE and probable new name. Name and ID WDS Theta Rho Mv1 Mv2 WDS Epoch R.A. Coordinate WDS DEC. STF 2590 AB STF 2590 AC STF 2590 CD New Pair AE Theta Rho Mv1 Mv2 Epoch R.A. Coordinate WDS DEC. AE ( ) Figure 2: Screen shot of SDSS astrometric data on the new E component.

31 Page 31 A New Companion for STF 2590, WDS (Continued from page 29) Conclusions One of the main questions is why has the E component not been cataloged? The article by Masa E. R. indicates the A component is a variable star, therefore it may be that the E component was not seen for the variability of the principal component. But a variable star may be the same component E, object of study for the next steps. Acknowledgments I thank the Washington Double Star Catalog and the for the information. I thank Florent Losse for excellent software Reduc. This work made use of the catalogs of The Aladin Sky Atlas. A special thanks to Adriano Dragone for the help and advice. References Brian D. Mason, Gary L. Wycoff, and William I. Hartkopf. Washington Double Star Catalog - ad.usno.navy.mil/wds/ The Aladin Sky Atlas - aladin.gml Sloan Digital Sky Survey - en/tools/explore/ Masa E. R., 2009 CCD Double-Star Measurementsat Observatorio Astronómico Camino de Palomares (OACP): First Series, JDSO, 5, 18, 2009.

32 Page 32 Divinus Lux Observatory Bulletin: Report #24 Dave Arnold Program Manager for Double Star Research 2728 North Fox Run Drive Flagstaff, AZ Abstract: This report contains theta/rho measurements from 109 different double star systems. The time period spans from to Measurements were obtained using a 20-cm Schmidt-Cassegrain telescope and an illuminated reticle micrometer. This report represents a portion of the work that is currently being conducted in double star astronomy at Divinus Lux Observatory in Flagstaff, Arizona. This article contains a listing of double star measurements that are part of a series, which have been continuously reported at Divinus Lux Observatory, since the spring of Beginning with this article, the selected double star systems, which appear in the table below, have been taken exclusively from the version of the Washington Double Star Catalog (WDS), with published measurements that are no more recent than ten years ago. There are also some noteworthy items that are discussed, which pertain to a few of the measured systems. As in previous articles, this report contains some double stars with noteworthy theta/rho shifts because of the effects of proper motion by one or both of the components. To begin with, proper motion by both component stars, for ES 1015 AB, has caused a 4% rho value increase during the past decade. Likewise, proper motion by both components, for STF 2944 AC, is responsible for a 4% rho value increase, but this occurred in just the last 5 years. Next, proper motion by the companion star, for GRV 440, caused a 2 degrees theta value decrease during the past 10 years. A rho value decrease of 5% is being reported for HJ Proper motion by both components, since 2001, is the cause for this shift. Two additional variances in the theta values for two more double stars are being noted. First, proper motion by the A component, for the BU 483 multiple star system, appears to have caused significant increases in the theta values for AC and AD during the past 10 years. Increases of over three degrees are being reported for both components. Secondly, the theta value for STF 140 AC, which appears in the table, is 2.5 degrees greater than the 1998 WDS value. Proper motion doesn t appear to be the cause in this case, but since this double star has few previous measurements, perhaps additional measurements will help bring more accuracy to this parameter. In a similar context, the rho measurement in this report, for HJ 3437, lines up more closely with the listing for 1836 than it does for the one in Additional measures of this pair might also be useful Some possible corrections are being suggested for the version of the WDS catalog. First of all, the 2005 theta value for STF 3008 ( ) might contain a typo, since the proper motion vectors imply a theta value increase rather than a decrease. Based upon measurements for this report, it appears

33 Page 33 that this value might be 159 degrees instead of 150 degrees. Secondly, the 2000 theta value for HJ 5547 ( ) reveals a 2 degrees increase from the 1991 value, when the proper motion vectors suggest just the opposite. The theta measurement appearing in this report seems to validate a decreasing theta value. Another unexplained discrepancy from catalog values pertains to STF 431 ( ). The WDS catalog lists the parameters for this double star as 249 degrees and 25.6 in 2001, but measurements of this pair on yielded theta/rho values of degrees and seconds. Proper motion shifts are not significant enough to account for this and no other pairs with similar parameters or magnitudes appear in this part of the sky. Perhaps other researchers might consider measuring this double star Divinus Lux Observatory Bulletin: Report #24 to either confirm the 2001 catalog values or the ones obtained for this report. In a similar context, the historical data in the WDS catalog seems to suggest a position angle increase, over time, for S 799AB ( ) but the position angle measurement obtained for this article is more closely in line with the value listed for Again, others may want to consider making additional position angle measurements of this pair in order to help verify the actual value. Finally, the rho measurement in the catalog for ARY 9 ( ), for 2002, appears to possibly be in error. The rho measurement in this report, for this double star, is much more closely aligned with the measurements in 1910, rather than the 2002 measurements. NAME RA DEC MAGS PA SEP DATE NOTES STF GRV ES ES 1015AB POP 145AB-CD STT 465 AB BU HJ STF2944AC STF ARG HJ BU 483AC BU 483AD HJ 1953AC HJ 1981A-BC STF HDO H 23AC H 23AD H 23AE H 23CE Table continues on next page.

34 Page 34 Divinus Lux Observatory Bulletin: Report #24 NAME RA DEC MAGS PA SEP DATE NOTES WEI S HJ STF 135AB-C STF 135AB-D STT 33AB DOB 2AC STF 140AC STF ENG STF 4AB BU 1368Bb STF 245Aa-B STT 27AB STF WEB STF 785AB STT 116AD BU 93AB H 125AB BRT GUI 10AC STF 889AB WAL 43AC A 2720AC STF1174AB-C WFC A 2367AB STF STF STF BU 111AC * STF ES STF 29AB Table continues on next page.

35 Page 35 Divinus Lux Observatory Bulletin: Report #24 NAME RA DEC MAGS PA SEP DATE NOTES WEB STF 32AC STF AG H 50AC STT STF 40AB STF 2498AB BOT 2AC STT 182AB HU STF 45AB ARY 23AB ARY 23BC ARY SHJ 323AD S 752AC ES STT 533AC STF 54AD STF 2780Aa-C WAL 137AB-E STF 55AB S 799AB S 799AC STF 2822AD HWE 59AB HJ 5524AD HJ 5355AB HJ 5355AC BU 1144Aa-BC STF 59AB-C S 823AC STF ES 2725AB Table concludes on next page.

36 Page 36 Divinus Lux Observatory Bulletin: Report #24 NAME RA DEC MAGS PA SEP DATE NOTES HJ 5413AB STF HJ 1929AB-C ARY 7AB ARY 8AB ARY 8AC ES ARY STF STF 17AB STF STT 10AB STT 10AC STF ES 224AC STF 70AB STF S BU 234AB BU 234AC HJ STT 23AB ENG 4AB HJ 2030AC AG ES 1712AB ES STT 30AC HJ ARN 32AE HJ 644AC BUP 26Aa-B FRK A 819AB-C BU 7AC

37 Page 37 Divinus Lux Observatory Bulletin: Report #24 Notes 1. In Delphinus. Sep. & p.a. increasing. Spect. G0. 2. In Vulpecula. Position angle decreasing. 3. In Cygnus. Relatively fixed. 4. In Cygnus. Separation increasing; position angle decreasing. 5. In Lacerta. Separation slightly increasing. 6. Sep. & p.a. decreasing. Spect. F0II. 7. In Pegasus. Position angle decreasing. Spect. F5, F5. 8. In Pegasus. Sep. increasing; p.a. decreasing. Spect. K0. 9. In Aquarius. Sep. increasing; p.a. decreasing. Spect. G2V, F Sep. and p.a. increasing. Spect. K0III, K In Cassiopeia. Position angle slightly increasing. Spect. K, A In Andromeda. Sep. & p.a. decreasing. Spect. F8, F In Andromeda. AC & AD = sep. & p.a. increasing. Spect. A & C = G5, G Ceti. Position angle decreasing. Spect. K In Cetus. Position angle slightly increasing. Spect. A5IV, G1V. 16. In Andromeda. Relatively fixed. Spect. G In Cetus. Sep. & p.a. increasing. Spect. G Phi or 34 Cassiopeiae. All components relatively fixed. Spect. AC = F5, B In Andromeda. Common proper motion; sep. & p.a. inc. Spect. G0, G In Pisces. Relatively fixed. Common proper motion. Spect. K1III, G In Cetus. Sep. increasing; p.a. decreasing. Spect. A7III, K In Andromeda. AB-C=fix.; c.p.m. AB-D=sep. & p.a. dec. Spect. AB-C= A In Cassiopeia. AB = sep. & p.a. inc. AC = relfix. Spect. AB = B3IV, K In Andromeda. Separation increasing. Spect. F2V, K In Cetus. Relatively fixed. Common proper motion. Spect. A, A. 26. Chi or 53 Ceti. Relatively fixed. Common proper motion. Spect. F3III Andromedae. AB = sep inc.; p.a. dec. Bb = relfixed. Spect. K0III, M In Andromeda. Common proper motion. Sep. & p.a. slightly inc. F3V, F3V. 29. In Aries. Relatively fixed. Common proper motion. Spect. A3, F In Perseus. Position angle increasing. Spect. B1.5IV. 31. In Orion. Position angle increasing. Spect. M7, M. 32. In Taurus. AB = sep. slightly increasing. AD = relatively fixed. Spect. B In Taurus. Common proper motion; p.a. slightly decreasing. Spect. A0, G In Camelopardus. Sep. increasing; p.a. decreasing. Spect. A4IV. 35. In Orion. Common proper motion; p.a. slightly decreasing. 36. In Orion. Sep. decreasing; p.a. increasing. Spect. B9.5III, F In Gemini. AB = p.a. increasing. AC = sep. & p.a. increasing. Spect. K In Orion. Position angle decreasing. Spect. F7V. 39. In Lynx. Relatively fixed. Common proper motion. Spect. F5, F In Hydra. Common proper motion. Sep. & p.a. slightly increasing. Spect. G In Leo. Common proper motion. Sep. slightly decreasing. Spect. G0, G In Leo. Sep. & p.a. increasing. Spect. G0, G. 43. In Leo. Separation decreasing. Spect. F0, A. 44. In Leo. Common proper motion; p.a. slightly increasing. Spect. A2, A In Sextans. Separation decreasing. Spect. of C = F In Crater. Relatively fixed. Common proper motion. Spect. F6V, F In Bootes. Separation decreasing. 48. Nu Coronae Borealis. Separation decreasing. Spect. M2III, K In Hercules. Relatively fixed. Common proper motion. Spect. A2V, A In Hercules. Relatively fixed. Common proper motion. Spect. K8, K In Ophiuchus. Common proper motion; p.a. increasing. Spect. F2, F In Hercules. Common proper motion; p.a. increasing. Spect. M0V, M In Scutum. Position angle increasing. Spect.

38 Page 38 Divinus Lux Observatory Bulletin: Report #24 K1II, K In Aquila. Relatively fixed. Common proper motion. Spect. G8II, A In Aquila. Separation slightly increasing. Spect. K0III, F In Aquila. AB = relfix; c.p.m. AC = relfix. Spect. AB = G5II, K. 57. In Cygnus. Sep. increasing; p.a. decreasing. Spect. F6V, A In Sagitta. Sep. & p.a. increasing. Spect. F In Aquila. Relatively fixed. Common proper motion. Spect. F4V, F5V. 60. In Cygnus. AB = sep. inc. BC = p.a. dec. Spect. AB = B0, F In Cygnus. Separation increasing. Spect. A0, K Rho or 11 Capricorni. Separation increasing. Spect. F3V, K In Delphinus. Relatively fixed. Common proper motion. Spect. B7IV, B In Cygnus. Relatively fixed. Spect. K Kappa or 7 Delphini. Relfixed. Common proper motion. Spect. G1, K Gamma or 5 Equulei. Sep. & p.a. decreasing. Spect. A9V, A In Cepheus. Aa-C & AB-E = p.a. slightly decreasing. Spect. B0II, B3, A In Cygnus. Separation decreasing. Spect. K5, F Cygni. AB = sep. decreasing. AC = sep. increasing. Spect. AB = A0V, A Mu or 1 Cygni. Sep. & p.a. decreasing. Spect. F7V, A In Aquarius. AB = relfix, cpm. AD = sep. inc; p.a. dec. Spect. AB = G8, G In Aquarius. AB = sep. inc.; p.a. dec. AC = p.a. dec. Spect. A5II, F6V, M Eta or 44 Pegasi. Separation increasing. Spect. G0, G Aquarii. Sep. decreasing; p.a. increasing. Spect. A9III, K Cassiopeiae. Relatively fixed. Spect. A5III, B In Pegasus. Sep. & p.a. slightly decreasing. Spect. G8III, G8III. 77. In Andromeda. Sep. & p.a. increasing. Spect. A2, G Aquarii. Sep. & p.a. decreasing. Spect. G0I, F. 79. In Pisces. Relatively fixed. Common proper motion. Spect. F0, F In Pegasus. Sep. increasing; p.a. decreasing. Spect. F In Cassiopeia. Sep. & p.a. increasing. Spect. F, A In Cassiopeia. AB = relfix, c.p.m. AC = relfix. Spect. B5, B9, B In Cassiopeia. Relatively fixed. Common proper motion. Spect. A2, F In Cassiopeia. Separation increasing. Spect. B5, G In Pisces. Relatively fixed. Common proper motion. Spect. F8, F In Andromeda. Separation increasing. Spect. K0, A. 87. In Andromeda. Relatively fixed. Common proper motion. Spect. G0, G In Pisces. AB = sep. inc. AC = p.a.inc. Spect. A5, F8, K In Cetus. Sep. increasing; common proper motion. Spect. G0, G In Andromeda. Separation increasing. Spect. A In Cassiopeia. Common proper motion; p.a. increasing. Spect. A0, A In Andromeda. Position angle decreasing. Spect. M. 93. In Cetus. Common proper motion; p.a. increasing. Spect. F5, F In Cetus. AB = sep. & p.a. inc. AC = sep. inc., p.a. dec. Spect. F0, F0, F In Andromeda. Relatively fixed. Common proper motion. Spect. A0, A In Cassiopeia. Relatively fixed. Common proper motion. Spect. F8, F In Andromeda. Position angle increasing. Spect. K In Cassiopeia. Relatively fixed. Spect. F2, A. 99. In Pisces. Relatively fixed. Common proper motion. Spect. F8, K In Cassiopeia. Sep. & p.a. decreasing. Spect. K In Cassiopeia. Sep. decreasing; p.a. increasing. Spect. K2, K In Pisces. Relatively fixed. Common proper

39 Page 39 Divinus Lux Observatory Bulletin: Report #24 motion. Spect. F8, G In Cetus. Relatively fixed. Common proper motion. Spect. F Cassiopeiae. Relatively fixed. Spect. B9, K In Pisces. Separation slightly increasing. Spect. K Zeta or 55 Ceti. Position angle decreasing. Spect. K0, K In Triangulum. Common proper motion; sep. slightly inc. Spect. F0, F In Triangulum. Relatively fixed. Common proper motion. Spect. F5, G In Cetus. Sep. & p.a. slightly increasing. Spect. A0, A0.

40 Page 40 Astrometric Measurements of Seven Double Stars, September 2011 Report Joseph M. Carro Cuesta College San Luis Obispo, California Abstract: From my residence in Paso Robles, California, measurements of the separation and position angle of seven double stars were made. Listed in chronological order, the double stars were Zeta Ursae Majoris, Zeta Lyrae, Epsilon Delphini, SAO in Sagitta, STF 2840 in Cepheus, 61 Cygni, and 17 Cygni. The two goals of this project were to measure the position angle and separation of the aforementioned double stars, and to learn the necessary techniques to conduct this research. Methodology My observations were made from my home in Paso Robles, California (located at approximately 35 o N and 120 o W) using a Celestron model CPC 1100 telescope (Figure 1). The telescope is computerized, motorized, and was fitted with a Celestron Micro Guide 12.5 mm astrometric eyepiece. The telescope is of Schmidt-Cassegrain design, with aperture of 11 inches on an alt-azimuth mount. The manufacturer reports a focal length of 2,800 mm. The Micro Guide eyepiece was oriented with the celestial coordinate system using the primary star of the double star under study. The primary star was positioned on the mark 30, the drive was disabled, and the star was permitted to drift to the outer circle. The scale was rotated until the star lay on the 270 degree mark. The accuracy of this setting was verified by positioning the primary star on the 90 degree mark of the outer circular scale, and allowing the star to drift to the 270 degree mark. Following the orientation, drift times were measured by placing the primary star on the 0 mark of the linear scale, and measuring the drift time from the 0 to the 60 mark using a stop watch precise to ±0.01 seconds. Measurements were made, and the average drift time was calculated. That average was used to calculate the scale constant Z, using the formula 14 : Figure 1: The author with his Celestron telescope

41 Page 41 Astrometric Measurements of Seven Double Stars, September 2011 Report T ave cosδ Z = D where Tave is the average time, δ is the declination angle, and D is the number of reticle divisions. Separation measurements were made by placing the pair of stars on the linear scale at the zero mark, and then counting the number of scale divisions between the stars. Because the scale has 60 divisions, it was only possible to estimate to the nearest ¼ division. After each measurement, the double star was repositioned to the next major division. Measurements were made, and an average and standard deviation were calculated. The position angle measurements were made by aligning both stars on the linear scale with the primary star at the 30 division and pointing to the 60 mark, disabling the tracking feature, and then allowing the stars to drift to the circular scales. The crossing of the primary star at the outer scale was approximated to the nearest degree as the scale has divisions of 5 o. Following each measurement, the tracking feature was enabled and the process was repeated. Zeta Ursae Majoris - Introduction This double star is located in the constellation of Ursa Major (the Great Bear), and is known by its traditional name of Mizar with alternate spellings of Mirzar, Mizat, and Mirza. This double star has been known since ancient times, and was the first double star. On clear nights, the double star can be seen without the use of instruments. It was studied by Benedetto Castelli in 1617, and has been studied frequently since that time. Both stars are yellow with magnitudes of 2.0 and The colors reported for this pair vary considerably having been reported as both white, white and emerald, both green, blue, or yellow. For the AB components, Right Ascension is 13 h 23 m 56 s and the Declination is +54 o What was once thought to be a double star is actually a complex of six stars which are all gravitationally bound 20. The catalog identifiers for this double star include 79 Ursae Majoris, ADS 8891AB, BD A, BGC 18133, FK5 497, HD , HIP 65378, HR 5054, SAO 28737, STF 1744, and WDS Its precise coordinates are Table 1: Literature Search; Separation (arc seconds); Position angle (degrees) for Zeta Ursae Majoris Reference name Sep PA William Herschel Catalog 1779 data Washington Double Star Cat data Eagle Creek Observatory Daley, Measurements by the author Zeta Ursae Majoris - Observations The measurements were made on 11 May 2011 (Bessell date ) beginning at 9:50pm and ending at 11:50pm Pacific Daylight Time. The night was clear and calm, and there was a ½ moon. The temperature ranged from 60 to 50 o F. There was a breeze of 5 10mph which affected the telescope and several measurements were repeated. The linear scale of the Micro Guide eyepiece was oriented with the celestial coordinate system using the primary star. Once the orientation was completed, 12 drift time measurements were made, with an average value of seconds, a standard deviation of 0.63 seconds, and a standard error of the mean of 0.18 seconds. The result was a scale constant of 6.8 arc seconds per division. The primary star was placed on the linear scale, and 12 separation measurements were taken. The average value was 2.2 divisions with a standard deviation of 0.22 divisions, and a standard error of the mean of 0.06 divisions. When adjusted for significant figures, the calculated separation was 14.7 arc seconds. The position angle measurements were made using the aforementioned methodology, and 18 position angle measurements were taken with an average value of o, a standard deviation of 1.5 o, and a standard error of the mean of 0.27 o. The separation value of 14.7 arc seconds and position angle value of o compared well with the separation value of 14.5 arc seconds and the position angle value of 152 o published in the Washington Double Star catalog. 35 See Table 1. Zeta Lyrae Introduction Located in the constellation of Lyra (the Harp), the double star Zeta Lyrae has been known since ancient times. Its right ascension is 18 h 44 m 46 s and its declination is +37 o The yellow primary and blue-white secondary stars have magnitudes of 4.4 and 5.7 respectively. Modern observations have

42 Page 42 Astrometric Measurements of Seven Double Stars, September 2011 Report shown that Zeta Lyrae is a spectroscopic binary (Wikipedia). The catalog identifiers for this pair include 6 Lyrae, BD , BU 968, CSV , GSC , HD , HIP 91971, HR 7056, PPM 81740, SAO 67321, STF 38, UBV 15954, and WDS Its precise coordinates are Zeta Lyrae Observations The measurements were made on 11 July 2011 (Bessell date ) beginning at 10:15pm and ending at 11:50pm Pacific Daylight Time. The night was clear, and the moon was gibbous. The temperature ranged from 60 to 50 o F. The wind was gentle at 1 5mph. The linear scale of the Micro Guide eyepiece was oriented with the celestial coordinate system using the primary star. Once the orientation was completed, 12 drift time measurements were made, with an average value of seconds, a standard deviation of 0.29 seconds, and a standard error of the mean of 0.08 seconds. The result was a scale constant of 7.13 arc seconds per division. The primary star was placed on the linear scale, and 12 separation measurements were taken. The average value was 6.17 divisions with a standard deviation of 0.25 divisions, and a standard error of the mean of 0.07 divisions. When adjusted for significant figures, the calculated separation was 44.0 arc seconds. The position angle measurements were made using the aforementioned methodology, and 18 position angle measurements were taken with an average value of o, a standard deviation of 2.18 o, and a standard error of the mean of 0.4 o. The separation value of 44.0 arc seconds and position angle value of o compared well with the separation value of 43.7 arc seconds and the position angle value of 150 o published in the Washington Double Star catalog 22. See Table 2. Epsilon Delphini - Introduction Located in the constellation of Delphinus (the Dolphin), the double star Epsilon Delphini consists of a pair of yellow-white stars of magnitudes 7.1 and 7.4. For the AB components, the right ascension is 20 h 31 m 12 s and its declination is +11 o It does not have a traditional name. The catalog identifiers for this pair include ADS 13946BC, AG , BD B, CSI , GC 28544, GCRV 12819, GEN , HD Table 2 Literature Review: Separation (arc seconds) and Position angle (degrees) for Zeta Lyrae Reference name Sep PA Washington Double Star Cat data Bright Star Catalog Burton, Perez, Arnold, Bell, Schlimmer data Washington Double Star Cat data Measurements by the author , HIP , IDS , PPM , SAO , SKY 38830, STF 2690, UBV M24917, and WDS J BC. Its precise coordinates are Epsilon Delphini Observations The measurements were made on 1 August 2011 (Bessell date ) beginning at 9:30pm and ending at 11:00pm Pacific Daylight Time. The night was clear, with no moon. The temperature range was from 65 to 55 o F. There was a 0 5mph breeze, and the humidity was 25%. The linear scale of the Micro Guide eyepiece was oriented with the celestial coordinate system using the primary star. Once the orientation was completed, 12 drift time measurements were made, with an average value of seconds, a standard deviation of 0.28 seconds, and a standard error of the mean of 0.08 seconds. The result was a scale constant of 7.11 arc seconds per division. The primary star was placed on the linear scale, and 12 separation measurements were taken. The average value was 2.5 divisions with a standard deviation of 0.0 divisions, and a standard error of the mean of 0.0 divisions. When adjusted for significant figures, the calculated separation was 17.7 arc seconds. The position angle measurements were made using the aforementioned methodology, and 18 position angle measurements were taken with an average value of 256 o, a standard deviation of 1.5 o, and a standard error of the mean of 0.28 o. The separation value of 17.7 arc seconds and the position angle of 256 o compared well with the values

43 Page 43 Astrometric Measurements of Seven Double Stars, September 2011 Report Table 3: Literature Review, Separation (arc seconds) and Position angle (degrees) for Epsilon Delphini Reference name Sep PA Washington Double Star Cat data The Hipparcos Catalog data Eagle Creek Observatory Arnold, Schlimmer, Schlimmer, Washington Double Star Cat data Table 4: Literature Review, Separation (arc seconds); Position angle (in o ) for SAO in Sagitta Reference name Sep PA W. Herschel (McEvoy 2011) data Hipparcos Catalog SKY2000 Master Catalog C C D M Catalog Arnold Washington Double Star Cat data Measurements by the author Schlimmer The Tycho Catalog Measurements by the author of 17.3 and 255 o as given in the Washington Double Star catalog 22. See Table 3. SAO in Sagitta Introduction Located in the constellation of Sagitta (the Arrow) is this double star of which the primary star is yelloworange and the secondary star is white. With magnitudes of 6.4 and 9.5, the secondary star approached the limit of the CPC 1100 telescope. Its Right Ascension is 19 h 39 m 25 s and its Declination is +16 o This double star has no traditional name. The catalog identifiers includeag , BC , GSC , HD , JIP 96688, HP 7475, IRAS , PPM , SAO , TYC , V 0340, and WDS A. Its precise coordinates are SAO in Sagitta Observations These measurements were made on 3 August 2011 (Bessell date ) beginning at 9:30pm and ending at 11:00pm Pacific Daylight Time. The night was clear, with a ¼ moon in the southwest. The temperature range was from 65 to 55 o F. There was a 0 5mph breeze. The humidity was 30%. The linear scale of the Micro Guide eyepiece was oriented with the celestial coordinate system using the primary star. Once the orientation was completed, 12 drift time measurements were made, with an average value of seconds, a standard deviation of 0.15 seconds, and a standard error of the mean of 0.04 seconds. The result was a scale constant of 7.3 arc seconds per division. The primary star was placed on the linear scale, and 12 separation measurements were taken. The average value was 4.0 divisions with a standard deviation of 0.0 divisions, and a standard error of the mean of 0.0 divisions. When adjusted for significant figures, the calculated separation was 29.0 arc seconds. The position angle measurements were made using the aforementioned methodology, and 18 position angle measurements were taken with an average value of 301 o, a standard deviation of 1.7 o, and a standard error of the mean of 0.31 o. The separation value of 29.0 arc seconds and position angle value of 301 o compared well with the separation value of 28.6 arc seconds and the position angle value of 301 o published in the Washington Double Star Catalog 22. See Table 4. STF 2840 in Cepheus Introduction Located in the constellation of Cepheus, this pair of yellow stars has magnitudes of 5.6 and 6.4. STF 2840 in Cepheus has been well studied, but little has been written about this pair. The WDS gives its Right Ascension is 21 h 52 m 01 s and its Declination is +55 o , however, the Cambridge Double Star Atlas lists an R.A. of 21 h 52 m 19 s and a Dec. of +55 o 50 10, and the data from the Hipparcos Catalog 28 is an R.A. of. 21 h 52 m 00 s and a Dec. of +55 o The catalog identifiers include ADS 15045, AG , BD , HD , HIP , IDS B, PPM 39938, SAO 33817, SKY 41670, TYC , UBV , and WDS B. Its precise coordinates are

44 Page 44 Astrometric Measurements of Seven Double Stars, September 2011 Report Table 5: Literature Review: Separation (arc seconds); Position angle (degrees) for STF 2840 in Cepheus Reference name Sep PA Washington Double Star Cat data Hipparcos Catalog data Eagle Creek Observatory Arnold Washington Double Star Cat data Measurements by the author Table 6: Literature Review, Separation (arc seconds) and Position angle (degrees) for 61 Cygni Reference name Sep PA W. Herschel (MacEvoy 2011) data Bright Star Cat Washington Double Star Cat data The Hipparchos Catalog data Arnold data Muller data STF 2840 in Cepheus Observations The measurements were made on 9 August 2011 (Bessell date ) beginning at 10:20 pm and ending at 11:30 pm Pacific Daylight Time. The night was clear, calm, with a gentle breeze of 1 5 mph. The moon was 2/3 full in the southwest. The temperature ranged from 60 to 50 o F. The humidity was 65%, and seeing was 3-4. The linear scale of the Micro Guide eyepiece was oriented with the celestial coordinate system using the primary star. Once the orientation was completed, 12 drift time measurements were made, with an average value of seconds, a standard deviation of 0.25 seconds, and a standard error of the mean of 0.08 seconds. The result was a scale constant of 7.3 arc seconds per division. The primary star was placed on the linear scale, and 12 separation measurements were taken. The average value was 2.5 divisions with a standard deviation of 0.0 divisions, and a standard error of the mean of 0.0 divisions. When adjusted for significant figures, the calculated separation was 18.1 arc seconds. The position angle measurements were made using the aforementioned methodology, and 18 position angle measurements were taken with an average value of 196 o, a standard deviation of 1.3 o, and a standard error of the mean of 0.24 o. The separation value of 18.1 arc seconds and position angle value of 196 o compared well with the separation value of 17.8 arc seconds and the position angle value of 197 o published in the Washington Double Star catalog 22. See Table Cygni Introduction Located in the constellation of Cygnus (the Swan) is 61 Cygni, a famous pair of orange stars. First studied Piazzi in 1792, the pair has a large proper motion Perez Schlimmer data Heijen Anton Oct Anton Oct Washington Double Star Cat data Measurements by the author of about 5 arc seconds per year, and is sometimes called the Flying Star 39. In 1838 Bessell measured the parallax and distance from the Earth for this pair, which was the first double star to be so measured 38. The orange pair is distinct, but the surroundings lack any prominent stars. The pair has magnitudes of 5.2 and 6.1. Its Right Ascension is 21 h 06 m 54 s and its Declination is +38 o The catalog identifiers include BD , FK5 793, HD , HIP , HR 8085, GC 29509, GJ 820, PPM 86045, SAO 70919, STF 2758, UBV 18287, and WDS Its precise coordinates are Cygni Observations The measurements were made on 14 August 2011 (Bessell date ) beginning at 8:45pm and ending at 9:30pm Pacific Daylight Time. The night was clear and calm with no moon. The temperature ranged from 75 to 65 o F. The humidity was 25%, and seeing at 4 5. The wind at 5-10mph affected the measurements, and many were repeated. The linear scale of the Micro Guide eyepiece was oriented with the celestial coordinate system using the primary star. Once the orientation was completed, 12 drift time measurements were made, with an average value of seconds, a standard devia-

45 Page 45 Astrometric Measurements of Seven Double Stars, September 2011 Report Table 7: Literature Review, Separation (arc seconds) and Position angle (degrees) for 17 Cygni Reference name Sep PA W. Herschel (MacEvoy 2011) data Starland Catalog (Olcott 1909) Washington Double Star Cat data Hipparcos Catalog Eagle Creek Observatory Astrogeek (Burton 2011) data Arnold Washington Double Star Cat data Measurements by the author tion of 0.37 seconds, and a standard error of the mean of 0.09 seconds. The result was a scale constant of 7.07 arc seconds per division. The primary star was placed on the linear scale, and 12 separation measurements were taken. The average value was 4.5 divisions with a standard deviation of 0.1 divisions, and a standard error of the mean of 0.03 divisions. When adjusted for significant figures, the calculated separation was 31.9 arc seconds. The position angle measurements were made using the aforementioned methodology, and 18 position angle measurements were taken with an average value of o, a standard deviation of 1.3 o, and a standard error of the mean of 0.31 o. The separation value of 31.9 arc seconds and the position angle value of 151 degrees compared favorably with the values of 31.4 arc seconds and 152 degrees as published in the Washington Double Star Catalog (Mason+ 2011) 22. See Table Cygni Introduction Located in the constellation of Cygnus (the Swan), 17 Cygni is a yellow pair of stars with magnitudes of 5.1 and 9.3. Its right ascension is 19 h 46 m 26 s and its declination is +33 o The catalog identifiers include ADS 12913A, BD , CSI , GC 27369, HD , HIP 97295, HR 7534, PLX 4654, PPM 83516, SAO 68827, STF 2580AB, TYC , and WDS Its precise coordinates are Cygni Observations The measurements were made on 15 August 2011 (Bessell date ) beginning at 8:30 pm and ending at 10:30 pm Pacific Daylight Time. The night was clear with moonrise at 9:30pm. The temperature ranged from 75 to 65 o F. The wind was 1-5mph, humidity 30%, and seeing 3 4. The linear scale of the Micro Guide eyepiece was oriented with the celestial coordinate system using the primary star. Once the orientation was completed, 12 drift time measurements were made, with an average value of seconds, a standard deviation of 0.2 seconds, and a standard error of the mean of 0.06 seconds. The result was a scale constant of 7.1 arc seconds per division. The primary star was placed on the linear scale, and 12 separation measurements were taken. The average value was 3.6 divisions with a standard deviation of 0.10 divisions, and a standard error of the mean of 0.03 divisions. When adjusted for significant figures, the calculated separation was 25.5 arc seconds. The position angle measurements were made using the aforementioned methodology, and 18 position angle measurements were taken with an average value of 68.9 o, a standard deviation of 1.35 o, and a standard error of the mean of 0.25 o. The separation value of 25.5 arc seconds and the position angle value of 69 degrees compared well with the values of 26 arc seconds and 69 degrees from the Washington Double Star Catalog 22. See Table 7. Acknowledgements The generous assistance of Russell Genet was instrumental in the execution of this work. Grateful thanks to John Baxter for his review of this paper. References 1. Anton R., Double and Multiple Star Measurements, The, vol 6 no 3, July Anton R., Double and Multiple Star Measurements,, vol 7 no 2, Arnold D. Divinus Lux report #16, Journal of Double Star Observations, vol. 5 no. 1 Winter Arnold D., Divinus Lux Observatory: Report #3,, vol 2 no 2, 2006

46 Page 46 Astrometric Measurements of Seven Double Stars, September 2011 Report 5. Arnold D., Divinus Lux Observatory: Report #6,, vol 2 no 3, Arnold D., Divinus Lux Observatory: Report #15,, vol 4 no 4, Arnold D., Divinus Lux Observatory: Report #20,, vol 6 no 1, Arnold D., Divinus Lux Observatory: Report #23,, vol 6 no 4, Bell, R., 2011, Stargazer Online, Burton J., 2011, Astrogeek Observatory ( 11. Daley J., Double Star Measures for the year 2005, The, vol 2 no 2, Daley J., Double Star Measures for the year 2006, The vol 3 no 2, Dommanget J., Nys O., Catalogue des composantes d étoiles doubles et multiples Frey T., Visual Double Star Measurement with an Alt-azimuth Telescope, Journal of Double Star Observations, vol 4 no 2 Spring Hog E., Baessgen G., Bastian U., Egret D., Fabricius C., Grossmann V., Halbwachs J., Makarov V., Perryman M., Schwekendiek P., Wagner K., Wicenec A., 1997, The Tycho Catalogue, 2011 from its website Heijen M., Star Observer website ( Hoffleit D., Warren W., 1991, The Bright Star Catalogue, 5th Revised Edition, Yale University 18. Johnson J., Genet R., Measurements of the Double Star STF 2079,, vol 3 no 4 Fall MacEvoy B., William Herschel s Double Star Catalogs Restored, Mamajek E., Kenworthy M., Hinz P., Meyer M., Discovery of a Faint Companion to Alcor Using MMT Imaging, Science Daily, Martín E, CCD Double Star Measurements,, vol. 5 no. 1 Winter Mason B., Wycoff G., Hartkopf W., Douglass G., Worley C., 2011, Washington Double Star Catalog 23. Muller R., Cerosimo J., Miranda V., Martinez C., Cotto D., Rosado-de Jesus I., Centeno D., Rivera L., Observation Report 2005, Journal of Double Star Observations, vol. 3 no. 2 Spring Muenzler K., 2003, Eagle Creek Observatory ( 25. Myers J., Sande C., Miller A., Warren W., Tracewell D., 2002, Sky 2000 Master Star Catalog, Goddard Space Flight Center, Flight Dynamics Division. 26. Olcott W., In Star Land with a 3 inch Telescope, G. P, Putnam and Sons Publisher, Perez J., Belt of Venus website ( Perryman M., Lindegren L., Kovalevsky J., Hog E., Bastian U., Bernacca P.L., Creze M., Donati F., Grenon M., Grewing M., van Leeuwen F., van der Marel H., Mignard F., Murray C., Le Poole R., Schrijver H., Turon C., Arenou F., Froeschle M., Petersen C., 1997, The Hipparcos Catalogue, 2011 from its website SAO Staff, (1996) Smithsonian Astrophysical Observatory Star Catalog. 30. Schlimmer J., Double Star Measurements Using a Webcam, Journal of Double Star Observations, vol 3 no 3, Schlimmer J., About Relative Proper Motion of 61 Cygni,, vol 5 no 2, Schlimmer J., Double Star Measurements Using a Webcam: Annual Report of 2008,, vol 5 no 2, Spring Schlimmer J., Double Star Measurements Using a Webcam: Annual Report of 2009,, vol 6 no 3, July 2010

47 Page 47 Astrometric Measurements of Seven Double Stars, September 2011 Report 34. Schupmann L., Ludwig Schupmann Observatory Measures of Large Δm Pairs Part Three, The, vol 5 no 3 Summer Worley C.E., Douglass G.G 1996, The Washington Visual Double Star Catalog 36. Worley C., Douglass G., 2006 The Washington Double Star Catalog 37. Daley J., Schupmann L., Double Star Measures for the Year 2006,, vol 3 no 2, Hirschfield A., Parallax: the Race to Measure the Cosmos, MacMillan Press Pannekoek A., A History of Astronomy, Courier Dover Publications, 1989

48 Page 48 Separation and Position Angle Measurements of Double Star STFA 46 and Triple Star STF 1843 Chandra Alduenda 1, Alex Hendrix 1, Navarre Hernandez-Frey 2, Gabriela Key 3, Patrick King 4, Rebecca Chamberlain 1, Thomas Frey 5 1. The Evergreen State College, Olympia, Washington 2. Kentridge High School, Kent, Washington 3. St. Mary s Academy, Portland, Oregon 4. Oregon Episcopal School, Portland, Oregon 5. California Polytechnic State University, San Luis Obispo, California Abstract: Various students and faculty all participated in the th annual summer astronomy workshop at Pine Mountain Observatory. Our group was trained in the proper techniques and skills required for measuring the separation and position angle of the binary star STFA 46 and trinary star STF We learned how to calibrate an astrometric eyepiece, make appropriate measurements, do a statistical analysis, and analyze data. The separation measurements our group made were comparable to current literature values. However, the observed position angles differed significantly from the literature. This discrepancy from literature values could be due to weather conditions or equipment limitations. Introduction A group of students, three new and two experienced observers, and an instructor from The Evergreen State College (TESC) participated in the fourth annual astronomy research workshop at the Pine Mountain Observatory (PMO) near Bend, Oregon. This year s topics were visual double star measurements and photometry. The workshop ran from July 24-28, All visual double star teams adopted team names; ours was Dubhe or Not Dubhe. The alt-az telescope used was an 18 Newtonian made by Obsession. The Celestron Micro Guide 12.5 mm illuminated astrometric eyepiece was calibrated and then separation and position angle measurements were taken. On night two, group members Hernandez- Frey, Key, and King, along with experienced observers Hendrix and Alduenda, joined their instructor Chamberlain and team leader Frey in observing double stars (DS). Since there were three members without DS observation experience, we decided to first Figure 1: Members of Dubhe or Not Dubhe. From left to right: Chandra Alduenda, Navarre Hernandez-Frey, Thomas Frey, Patrick King, Gabriela Key, Alex Hendrix, Rebecca Chamberlain

49 Page 49 Separation and Position Angle Measurements of Double Star STFA 46 AB and Triple Star... Star System Table 1: Data for STFA 46 AB Parallax (mas) Proper Motion (mas/year) Right Ascension Declination Spectral Type STFA 46A G1.5Vb STFA 46B G3V Star System Table 2: Data for STF 1843 AB Parallax (mas) Proper Motion (mas/ year) Right Spectral Declination Ascension Type STF1843A F5 STF1843B F5 study the bright DS STFA 46 that had good separation so they could understand the technique. Directly after this, we observed the triple or trinary star (TS) STF 1843 in the constellation Bootes. The data was analyzed and each student was assigned a topic to write up for the published paper. Alduenda and Hendrix were assigned to write a more extensive part of the paper. Background The double star STFA 46 (also known as 16 Cygni) is actually a triple star system composed of an AC-B combination. STFA 46 A (HD186408) has a close binary (16 Cygni C) first resolved by Turner (2001). The AC binary has a separation and position angle of 3.4 arc seconds and 209 degrees, respectively, with a projected separation of 73 AU. The C component may be a red dwarf (Raghavan, 2006). STFA 46 B has a Jupiter-mass planet orbiting the star with a period of 2.2 years and an eccentricity of 0.69 (Mazeh, 1996). Due to the close agreement of parallax, proper motion, and spectral types shown in Table 1, STFA 46 AB is considered to be a binary pair (Hipparcos and Tycho, 1997), (Simbad database). The triple star STF 1843 is in the constellation Bootes. The parallax, proper motion and spectral type for the A and B components are given in Table 2 (Hipparcos Catalog, The SkyX). The values for proper motion and spectral type indicate a very close association for both A and B so they likely both originated in the same collapsing gas cloud, indicating a possible binary relationship. The parallax difference between A and B is converted to a distance of 38.2 parsecs (124.3 light years). The C component is a G5 star with a right ascension and declination proper motion of and , respectively (The SkyX). This indicates the star is an optical component of the AB system. Locale and Observing Conditions The study was carried out at Pine Mountain Observatory near Bend, Oregon. The Observatory is located at degrees north latitude and degrees west longitude. Due to high winds, humidity, and dew, the first night of observation was cancelled. The second night was more favorable with some breeziness at times that could have affected some measurements. The seeing was good with only moderate scintillation. At times, the transparency was not favorable. Calibration of the Celestron Astrometric Eyepiece The linear scale on the Celestron 12.5 mm astrometric eyepiece, divided into 60 equal divisions, must be calibrated for each telescope-eyepiece assembly to determine the scale constant in arc seconds per division. This has been described at length previously (Frey, 2008). The reference star Navi (Gamma Cassiopeia) was used for this calibration because its declination lies within the recommended degree range for calibration (Argyle, 2004). The results are given in Table 3. SD and ME are the standard deviation and the standard error of the mean. Double Star STFA 46 Literature Values Once the scale constant had been determined, the 18-inch Obsession was two-star aligned and the tracking motors engaged. Because several of the observers on the team were inexperienced in using an alt-az telescope, a well-studied double star was chosen for initial study; STFA 46 in the constellation Reference Star Besselian Epoch Table 3: Scale Constant Determination Declination (degs) # Observ. Ave.Drift Time(secs) SD/ME (secs) Scale Constant (asec/div) Navi /

50 Page 50 Separation and Position Angle Measurements of Double Star STFA 46 AB and Triple Star... Star System Identifier Table 4: Separation Measurements of STFA 46 and STF Bessel. Epoch Literature Epoch # Observ. SD/ME (as) ObvSep (as) LitSep (as) STFA 46AB / STF1843AB / STF1843AC / Star System Table 5: Position Angle Measurements for STFA 46 and STF Identifier Bessel. Epoch Literature Epoch Cygnus, first studied in 1800 and most recently in 2010 (Mason, 2009). The most recent Washington Double Star (WDS) Catalog 2010 position angle and separation values were 133 degrees and 39.7 arc seconds, respectively. The primary and secondary magnitudes were 6.0 and 6.2. The right ascension and declination of the primary star are 19h 41m 49.1s and m 31.6s. Table 1 gives additional data for STFA 46 AB. Triple Star STF 1843 The most recent study published in the WDS Catalog of the triple star STF 1843 ABC in the constellation Bootes was done in 2007, where the position angle for the AB component was 187 and a separation of 19.8 arc seconds. The primary and secondary stars had magnitudes of 7.68 and 9.23, respectively. The STF 1843 AC position angle was 64 with a separation of 98.8 arc seconds. The C component had a magnitude of Table 2 gives additional data for STF 1834 ABC. Separation Measurements of STFA 46 and STF 1843 The telescope was two-star aligned and the servomotors engaged. The Celestron Micro Guide eyepiece was rotated until the central linear scale was parallel with the axis joining the two stars. The distances between the centers of the two stars was estimated to the nearest 0.1 divisions and recorded. Then, using the slow motion controls, the stars were shifted to a new location along the linear scale, and a new measurement was made. We repeated this process times, taking turns among all members of the group. # Observ. SD/ME (degs) ObvPA (degs) LitPA (degs) STFA 46AB / STF 1843AB / STF 1843AC / This method of moving stars to new locations along the linear scale for each measurement was made to negate bias errors that might exist if the stars were continually kept and measured at the same division marks. Due to possible field rotation, the eyepiece was continually adjusted so that the two stars remained aligned with the linear scale. The SD/ME are standard deviation and standard error of the mean. The observed and literature separations are given in arc seconds. The separation measurements for STFA 46 and STF 1843 are shown in Table 4. Position Angle Measurements of STFA 46 and STF 1843 The determination of the position angle using the drift method with the alt-az telescope has been described at length in a previous paper (Frey, 2008). Briefly, it involves disengaging the servo-motors so that the telescope becomes a push Dob. The double star is aligned with the linear scale and adjusted manually so, when the telescope is released, the primary star drifts through the 30 th division mark on the linear scale. This proper drift is difficult to do and usually takes several attempts to accomplish. Second, a parallax error can occur as the primary star crosses the outer protractor scale that can lead to an erroneous position angle. Third, aligning the two stars on the linear scale becomes more challenging as the separation becomes smaller. If not properly aligned, the position angle will be radically altered. To circumvent these potential problems, drift cycles were carried out, and the cycles averaged to obtain the best

51 Page 51 Separation and Position Angle Measurements of Double Star STFA 46 AB and Triple Star... mean value. Due to possible field rotation, the eyepiece was continually adjusted so that the two stars remained aligned as much as possible with the linear scale. Special effort was made to realign the stars parallel to the scale and the eyepiece tightened in the draw tube. Position angles (PA) are given in degrees. The SD/ME are standard deviation and standard error of the mean. The position angle measurements for STFA 46 and STF 1843 are shown in Table 5. Discussion Separation measurements on the two multi-star systems were carried out using only the Celestron Micro Guide eyepiece. Table 4 shows the observed and most recent WDS literature separation values. If the observed separation values are compared in the order conducted, we see for STFA 46 AB, STF 1843 AB, and STF 1843 AC that the percent differences based on the literature values were 8.1%, 5.5%, and 0.1%, respectively. Because three of the five students taking measurements had never done this before, this decreasing trend in percent error shows that the observers were learning observation techniques very rapidly. This is why it is wise to initiate beginning observers with very bright and well-separated double stars. The observed position angle measurements did not correlate well with the literature values. There are many possible reasons for these errors. The observed and literature values for the position angles are shown in Table 5. The observed position angles for STFA 46 AB, STF 1843 AB, and STF 1843 AC differed from literature values by 4, 7, and 5 degrees, respectively. Let s account for some of these discrepancies. First, weather may have contributed to these errors. Occasional breezes would occur during a PA drift cycle enough to nudge the push Dob away from a proper drift. Yet, Grubbs Critical Value outlier formula (Burke, 1998) for a 99% confidence level determined that none of the collected data qualified as outliers but errant breezes could have moved the telescope enough to alter the observed position angle. Second, to cancel out possible field rotation and bias readings, the eyepiece was rotated and realigned after several drift cycles. In the realignment process, the eyepiece was rotated so the linear scale was coaligned with the axis passing through the two stars and the eyepiece was tightened with a set-screw on the draw tube. During the securing of the set-screw, the eyepiece had a tendency to rotate. So unless the eyepiece was tightly held in place while being secured, it could have rotated and thus be misaligned with the axis of the two stars. The third and most likely explanation deals with the separation between the two stars. This is especially true of STF 1843 AB with a literature separation of 19.8 arc seconds. Because only the Celestron Micro Guide eyepiece was used to make the measurements, the scale constant was 10.2 arc seconds per division. So a 19.8 arc second separation spans less than 2 divisions on the linear scale. This is a very small distance to accurately align for the PA drift. Whereas a slight misalignment of this span in measuring separations would not affect the results significantly, a small tilt in the alignment would make a significant error in the position angle value. See Figure 2. There are other possible reasons for position angle errors observed for STFA 46 AB, some of which can be traced to the recorded values themselves. Eight of the fifteen values ranged between and seven ranged from Seven different observers recorded the 15 position angles in the course of the study. In some instances, one observer would begin the drift cycle (because adjusting the telescope to the proper drift position is very difficult for some) and then switch off in mid-drift to another observer, who would watch the pair cross the protractor scale and announce the value. We now know this is an ineffective procedure. There is the possibility that the observer could be watching the wrong star, that is, the secondary instead of the primary. This is complicated by the fact that the two stars have almost identical magnitudes; 6.0 and 6.2. This would change the observed position angle to a whole new data set. If only the eight observations ranging from were considered, the mean position angle would have been 131 with a standard deviation and mean error of 1.30 and 0.46, respectively. The most severe difference between observed and literature values of position angles occurred with STF 1843 AB. As indicated in Figure 2, the 19.8 arc second separation makes alignment for the drift procedure especially challenging. There were ten recorded position angles ranging from and the literature value was 187. Because all of the observed values were less than the literature value, the latter was rechecked. WDS values indicated the position angle in 1830 and 2007 both having 187. TheSkyX value was minutes, showing close agreement. The recorded position angles were reviewed again to make

52 Page 52 Separation and Position Angle Measurements of Double Star STFA 46 AB and Triple Star... Figure 2: Possible Position Angle Errors Due to Misalignment on Linear Scale sure that the data was correct. Six of the ten values ranged from while the other four values ranged from The range of observed values between separate observers in our group does not appear to be random. This outcome could have been caused by ineffective tightening of the astrometric eyepiece in the draw tube. The eyepiece would have been skewed in the same direction each time leading to consistently incorrect position angles. The four values between were taken concurrently so all of the observers could have been looking at the secondary star. A similar pattern of observed position angles with respect to literature values is noted for STF 1843 AC. The ten recorded position angles ranged from with a mean of 58. The literature value was 64. The literature values were again rechecked: WDS at 64 (2007) and TheSkyX at 63 6 minutes. All but one of the observed values were less than the literature value, indicating some source of systematic error. The misaligned astrometric eyepiece is the most probable source of error. In order to alleviate this problem in future studies, several operations are considered essential. First, for separation values less than 30 arc seconds, it is recommended that a 2x-3x Barlow lens be used in conjunction with the astrometric eyepiece so the increased magnification will allow a more accurate alignment of the pair of stars on the linear scale. This should only be done, however, when the atmospheric conditions are conducive. In the case of this study, the breeze factor was too great to allow use of the Barlow. Also, since moderate scintillation was present it would make alignment and reading of both separation and position angle difficult. Second, limit the number of people doing a particular measurement to one observer. For this workshop the exercises and measurements carried out were for education and training. However, allowing more than one person to take a particular reading could have resulted in faulty results. Student Reflections Three of the five students making double star observations had never attempted this kind of science research before. Their efforts included instrument setup, orientation, instruction, making observations, analysis, presentation of data to their peers, and documentation of their experiences. The following is a paraphrased summary of their reflections. The double star STFA 46 AB were two stars with magnitudes of 6.0 and 6.2. This made it easy at times to see the stars separation and drift as they were clearly visible. Being able to work together as a group, having a positive attitude, helping explain to the next person where to look in the eyepiece and how to control the alt-az hand pad seemed to be extremely helpful. Other things that made data collection smoother were the handouts the lead professor gave us. These were handouts on how to calibrate the eyepiece, using databases for double star research, and data collection. Also, working with college professors offered a rare experience for high school students, and having college students with astronomical experience as team captains deepened the experience further. The two college students in the group taught us how to make observations and calmed fears of not getting the data correct or done in time. One way they did this was by drawing a diagram of the astrometric eyepiece and explaining how to read measurements on it. This really helped us because we were not familiar with this equipment. We had a night of unfavorable weather which required us to do the double star and triple star meas-