Jonckheere Double Star Photometry Part III: Lyra, Equuleus, and Eridanus

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1 Page 351 Jonckheere Double Star Photometry Part III: Lyra, Equuleus, and Eridanus Wilfried R.A. Knapp Vienna, Austria Abstract: If any double star discoverer is in urgent need of photometry then it is Jonckheere. There are over 3000 Jonckheere objects listed in the WDS catalog and a good part of them have magnitudes which are obviously far too bright. To keep the workload manageable only one image per object is taken and photometry is done with a software allowing a simple point and click procedure even a single measurement is better than the currently usually given estimation. 1. Introduction As follow up to the first two reports on J-objects in Cygnus (Knapp; Nanson 2016) and Delphinus (Knapp 2016) I selected for this report all J-objects in Lyra (Lyr), Equuleus (Equ), and Eridanus (Eri) given in the Tables 1 to 3 with all values based on WDS data as of April Measurements 2.1 Photometry for the J-objects in Lyra For each of the listed J-objects one single image was taken (in Bessel epoch ) with itelescope it24 with 3 second exposure time. The initial plate solving was done by AAVSO VPhot and in the few cases with negative VPhot result again but positive with MaxIm DL6/PinPoint. Each image was then once more plate solved with Astrometrica using the UCAC4 catalog with reference stars in the Vmag range of 10.5 to 14.5 giving not only RA/Dec coordinates but also photometry results for all reference stars used including an average dvmag error. The J-objects were then located in the center of the image (worked fine with few exceptions indicating that the given RA/Dec coordinates are usually correct with the exceptions suggesting position problems) and photometry was then done using the Astrometrica procedure with point and click at the components delivering Vmag measurements based on all reference stars used for plate solving. The only changing parameter was the aperture radius used for photometry aiming to keep it equal or at least near 1.5x FWHM. In cases with smaller separation the star disks touched or overlapped but allowed nevertheless individual photometry even if less reliable than with clear separated disks. J110 allowed only the measurement of the combined magnitude but even in this case it is then possible to make a well-founded estimation for the components based on the initial observed m between the components based on the formula m combined 10 m 2.5log m 1` 2 according to Greaney Measurements of the J-objects in Lyra are given in Table Photometry and Astrometry for the J-objects in Equ Beginning with the J-objects in Equ, I decided to provide photometric results and astrometric measurements in the form of RA/Dec coordinates resulting from plate solving as well as separation and position angle calculated based on the RA/Dec coordinates of the components. This is done by using the spherical trigonometry formulas provided by Buchheim Measurements of the J-objects in Equ are given in Table Photometry and Astrometry for the J-objects in Eri In Table 6, I again report photometric results and astrometric measurements in the form of RA/Dec coordinates resulting from plate solving as well as separation and position angle calculated based on the RA/Dec coordinates of the components. This is done by using the spherical trigonometry formulas provided by Buchheim Table 6 gives the measurements of the J-objects in Eri. (Continued on page 360)

2 Page 352 Table 1: WDS April 2015 values for the Jonckheere objects in Lyra sorted by designation number WDS ID Name RA Dec Sep M1 M2 PA J110 AB 18:51: :24: J112 AB 19:01: :37: J131 AB 18:49: :23: J525 AB 18:38: :37: J760 AB 18:22: :30: J761 AB 18:27: :36: J762 AB 18:30: :34: J763 AB 18:30: :26: J764 AB 18:34: :54: J765 AB 18:49: :25: J766 AB 19:02: :27: J766 AC 19:02: :27: J767 AB 19:06: :49: J767 AC 19:06: :49: J768 AB 19:13: :46: J769 AB 19:20: :12: J811 AB 19:03: :56: J1138 AB 18:38: :00: J1205 AB 19:07: :28: J1206 AB 19:11: :12: J1208 AB 18:49: :34: J1209 AB 19:04: :06: J1263 AB 19:11: :53: J1263 BC 19:11: :53: J2941 AB 19:04: :51: J2942 AB 19:05: :49: J2945 AC 19:07: :43: J3213 AB 19:06: :15: J3313 AB 19:14: :45:

3 Page 353 Table 2: WDS April 2015 values for the Jonckheere objects in Equuleus sorted by designation number WDS ID Name RA Dec Sep M1 M2 PA J158 AB 21:02: :17: J159 AB 21:08: :37: J161 AB 21:22: :57: J576 AB 21:12: :45: J608 AB 20:59: :13: J848 AB 21:09: :28: J913 AB 20:59: :28: J914 AB 21:24: :46: J1039 AB 21:25: :47: J1356 AB 21:22: :52: J1721 AB 21:19: :40: J1781 AB 21:06: :36: J2341 AB 21:19: :37: J2576 AB 21:06: :29: J2605 AB 21:22: :13: Table 3: WDS April 2015 values for the Jonckheere objects in Eridanus sorted by designation number WDS ID Name RA Dec Sep M1 M2 PA J318 AB 04:53: :39: J319 AB 05:04: :12: J708 AB 04:23: :34: J709 AB 04:29: :34: J710 AB 04:38: :42: J1003 AB 04:58: :06: J1004 AB 05:08: :30: J1087 AB 04:30: :37: J1245 AB 02:47: :00: J1453 AB 02:50: :16: J1453 AC 02:50: :16: J1455 AB 03:03: :14: J1456 AB 03:17: :22: J1457 AB 03:36: :20: J1459 AB 04:21: :25:

4 Page 354 Table 4. Bessel epoch photometry results for the J objects in Lyr. M1 WDS and M2 WDS are the WDS catalog values. M1 new stands for measured M1, dm1 stands for delta between M1 WDS and M1 new. M2 new stands for measured M2, dm2 stands for delta M1 WDS and M1 new. Err M1 stands for the estimated error range calculated from the average delta Vmag over all reference stars used in the image and the SNR value of the star with the formula SQRT(dVmag^2+(2.5*LOG10(1+1/SNR))^2 WDS ID Name M1 WDS M1 new dm1 Err M1 M2 WDS M2 new dm2 Err M2 Notes J110 AB disks - no separate photometry possible. Combined magnitude with SNR gives estimated M1 new and M2 new values confirming rather well the current WDS values J112 AB A too bright for reliable photometry No resolution of B J131 AB suggests B being far fainter than listed J525 AB J760 AB J761 AB J762 AB J763 AB Touching/Overlapping star disks J764 AB J765 AB Touching star disks J766 AB Touching star disks J766 AC J767 AB J767 AC J768 AB SNR for B < J769 AB J811 AB Touching star disks SNR for B < J1138 AB Touching star disks J1205 AB J1206 AB J1208 AB J1209 AB No double star at this position. Nearby A and B with dra 0.14 and ddec 0.15 giving Sep 2.643" with Err and PA with Err Minor position issue: A with dra 0.14 and ddec 0.15 giving Sep 4.676" with Err and PA with Err Table 4 concludes on next page.

5 Page 355 Table 4 (conclusion). Bessel epoch photometry results for the J objects in Lyr. M1 WDS and M2 WDS are the WDS catalog values. M1 new stands for measured M1, dm1 stands for delta between M1 WDS and M1 new. M2 new stands for measured M2, dm2 stands for delta M1 WDS and M1 new. Err M1 stands for the estimated error range calculated from the average delta Vmag over all reference stars used in the image and the SNR value of the star with the formula SQRT(dVmag^2+(2.5*LOG10(1+1/SNR))^2 WDS ID Name M1 WDS M1 new dm1 Err M1 M2 WDS M2 new dm2 Err M2 Notes J1263 AB A too bright for reliable measurement, star disk looks elongated, might be a close double itself J1263 BC SNR for C < J2941 AB SNR for B < J2942 AB SNR for B < J2945 AC Mag for HLM16 B measured with with SNR (WDS lists 12.7mag) Notes regarding the notes column: Touching star disks indicates that the rims of the star disks are touching and that the measurement results might be a bit less precise than with clearly separated star disks Overlapping/Touching star disks indicates that the star disks overlap to the degree of an elongation and that the measurement results is probably less precise than with clearly separated star disks disks indicates star disk overlap to the degree that photometry for the separated components was no longer possible and that it was necessary to resort to the measurement of the combined magnitude Low SNR <20 indicates that the measurement result might be a bit less precise than desired due to a low SNR value but this is already included in the calculation of the error range estimation too bright for reliable photometry indicates a star far brighter than the for plate solving used range 10.5 to 14.5mag despite this most such cases showed a reasonable measurement result anyway In case of questionable astrometric data separation and position angle is calculated based on the RA/Dec coordinates of the components. This is done using the formulas provided by Buchheim 2008 Specifications of the used telescope: T24: 610mm CDK with 3962mm focal length. Resolution arcsec/pixel. V-filter. No transformation coefficients available. Located in Auberry, California. Elevation 1405m

6 Page 356 Table 5. Bessel epoch astrometry and photometry results for the J objects in Equ plus BRT1355 as bonus. Number of observations is 1. RA and Dec are the coordinates based on plate solving with UCAC4 reference stars in the 10.5 to 14.5mag range. Sep is separation calculated as SQRT(((RA2-RA1)*cos(Dec1))^2+(Dec2-Dec1)^2) in radians. Err Sep is the error estimation for Sep calculated as SQRT(dRA^2+dDec^2). The position angle PA is calculated as arctan((ra2-ra1)*cos (Dec1))/(Dec2-Dec1)) in radians and Err_PA is the error estimation for PA calculated as arctan(err_sep/sep) in degrees assuming the worst case that Err_Sep points in the right angle to the direction of the separation means perpendicular to the separation vector. Err Mag stands for the estimated error range calculated from the average delta Vmag over all reference stars used in the image and the SNR value of the star with the formula SQRT(dVmag^2+(2.5*LOG10(1+1/SNR))^2) Name RA Dec Sep Err Sep PA Err PA Mag Err Mag Notes J 158 A SNR for B<20 B J 159 A B J 161 J 576 J 608 J 848 J 913 J 914 J 1039 A Touching/ B disks A Touching/ B disks A SNR for B<10, barely to see B A Touching/ B disks A Touching/ B disks A Touching/ B disks A SNR for B<20 B J 1356 A B J 1721 A B Table 5 concludes on next page.

7 Page 357 Table 5 (conclusion). Bessel epoch astrometry and photometry results for the J objects in Equ plus BRT1355 as bonus. Number of observations is 1. RA and Dec are the coordinates based on plate solving with UCAC4 reference stars in the 10.5 to 14.5mag range. Sep is separation calculated as SQRT(((RA2-RA1)*cos(Dec1))^2+(Dec2-Dec1)^2) in radians. Err Sep is the error estimation for Sep calculated as SQRT(dRA^2+dDec^2). The position angle PA is calculated as arctan((ra2- RA1)*cos(Dec1))/(Dec2-Dec1)) in radians and Err_PA is the error estimation for PA calculated as arctan(err_sep/sep) in degrees assuming the worst case that Err_Sep points in the right angle to the direction of the separation means perpendicular to the separation vector. Err Mag stands for the estimated error range calculated from the average delta Vmag over all reference stars used in the image and the SNR value of the star with the formula SQRT(dVmag^2+(2.5*LOG10(1+1/SNR))^2) Name RA Dec Sep Err Sep PA Err PA Mag Err Mag Notes J 1781 A B J 2341 A B J 2576 A B SNR for A and B<20. No good match with the original Jonckheere 12/13 mags J 2605 BRT1355 A Touching/ B disks A Touching star disks B Notes regarding the notes column: indicates that the given values base on one it27 image with 3 seconds exposure time. Touching star disks indicates that the rims of the star disks are touching and that the measurement results might be a bit less precise than with clearly separated star disks. Overlapping/Touching star disks indicates that the star disks overlap to the degree of an elongation and that the measurement results is probably less precise than with clearly separated star disks. disks indicates star disk overlap to the degree that photometry for the separated components was no longer possible and that it was necessary to resort to the measurement of the combined magnitude. Low SNR <20 indicates that the measurement result might be a bit less precise than desired due to a low SNR value but this is already included in the calculation of the error range estimation. too bright for reliable photometry indicates a star far brighter than the range used in plate solving (mag to 14.5), despite this most such cases showed a reasonable measurement result anyway. Specifications of the used telescope: it27: 700mm CDK with 4531mm focal length. CCD: FLI PL Resolution 0.53 arcsec/pixel. V-filter. No B-V transformation coefficients available. Located in Siding Spring, Australia. Elevation 1122m

8 Page 358 Table 6. Bessel epoch astrometry and photometry results for the J objects in Eri. Number of observations is 1. RA and Dec are the coordinates based on plate solving with UCAC4 reference stars in the 10.5 to 14.5mag range. Sep is separation calculated as SQRT(((RA2-RA1)*cos(Dec1))^2+(Dec2-Dec1)^2) in radians. Err Sep is the error estimation for Sep calculated as SQRT(dRA^2+dDec^2). The position angle PA is calculated as arctan((ra2-ra1)*cos(dec1))/(dec2-dec1)) in radians and Err_PA is the error estimation for PA calculated as arctan(err_sep/sep) in degrees assuming the worst case that Err_Sep points in the right angle to the direction of the separation means perpendicular to the separation vector. Err Mag stands for the estimated error range calculated from the average delta Vmag over all reference stars used in the image and the SNR value of the star with the formula SQRT(dVmag^2+(2.5*LOG10(1+1/SNR))^2) Name RA Dec Sep Err Sep PA Err PA Mag Err Mag Notes J 318 A B J 319 A B J 708 A Touching/ B disks J No resolution but elongation according to the listed WDS PA. Combined magnitude suggests 10.93/11.07mag for A/ B keeping the given delta_m J 710 A B Touching star disks J 1003 A B J 1004 A B J 1087 A Touching/ B disks J 1245 A Touching/ B disks Table 6 concludes on next page.

9 Page 359 Table 6 (conclusion). Bessel epoch astrometry and photometry results for the J objects in Eri. Number of observations is 1. RA and Dec are the coordinates based on plate solving with UCAC4 reference stars in the 10.5 to 14.5mag range. Sep is separation calculated as SQRT(((RA2-RA1)*cos(Dec1))^2+(Dec2-Dec1)^2) in radians. Err Sep is the error estimation for Sep calculated as SQRT(dRA^2+dDec^2). The position angle PA is calculated as arctan((ra2-ra1)*cos(dec1))/(dec2- Dec1)) in radians and Err_PA is the error estimation for PA calculated as arctan(err_sep/sep) in degrees assuming the worst case that Err_Sep points in the right angle to the direction of the separation means perpendicular to the separation vector. Err Mag stands for the estimated error range calculated from the average delta Vmag over all reference stars used in the image and the SNR value of the star with the formula SQRT(dVmag^2+(2.5*LOG10(1+1/SNR))^2) Name RA Dec Sep Err Sep PA Err PA Mag Err Mag Notes J 1453 A B J 1453 A C J 1455 A B J 1456 A B J 1457 A Touching star disks B J 1459 A Touching star disks B Notes regarding the notes column: indicates that the given values base on one it27 image with 3 seconds exposure time. Touching star disks indicates that the rims of the star disks are touching and that the measurement results might be a bit less precise than with clearly separated star disks. Overlapping/Touching star disks indicates that the star disks overlap to the degree of an elongation and that the measurement results are probably less precise than with clearly separated star disks. disks indicates star disk overlap to the degree that photometry for the separated components was no longer possible and that it was necessary to resort to the measurement of the combined magnitude. Low SNR <20 indicates that the measurement result might be a bit less precise than desired due to a low SNR value but this is already included in the calculation of the error range estimation. too bright for reliable photometry indicates a star far brighter than the for plate solving used range 10.5 to 14.5mag despite this most such cases showed a reasonable measurement result anyway. Specifications of the used telescope: -it27: 700mm CDK with 4531mm focal length. CCD: FLI PL Resolution 0.53 arcsec/pixel. V-filter. No B-V transformation coefficients available. Located in Siding Spring, Australia. Elevation 1122m

10 Page 360 (Continued from page 351) 3. Summary All result tables show, with some exceptions, quite large differences for the magnitudes compared with the WDS data often even in cases where double digit values suggest recent precise measurements. But it is obvious that the Jonckheere objects in more southern constellations have been visited rather often compared to the J-objects in the more northern constellations also with the effect of a far better data quality. A few cases suggest errors in position, separation, and position angle as the difference to the WDS data is larger than the given error estimation. In some cases the available equipment did not allow separate measurement due to heavily overlapping star disks. The measurement of the combined magnitude allowed an estimation of the components on the basis of the given m using the formula provided by Greaney Special cases: J131B in Lyr: No resolution, B probably fainter than +13mag J1206 in Lyr: WDS gives here for unknown reasons a position slightly different from the WDS ID. The measured position is a better match with the WDS ID (assumed to be the original position given by Jonckheere) and is also confirmed by an elongation in the 2MASS image J1208 in Lyr: Position error in WDS catalog by about 72 arcseconds. Measured position confirmed by UCAC4 catalog with and J2576 in Equ: No good match with the original Jonckheere 12/13 mag estimation. J2576 was not found at the given IDS position by Heintz according to his 1990 paper and the current precise WDS position seems to be given for a potential candidate with similar parameters for separation and position angle but at the cost of a rather bad match of the estimated magnitudes compared with the measured 14.45/14.15mag regarding not only delta_m but also position of the primary. Measurement results confirmed by UCAC4 catalog objects and Unfortunately the star field around the given position does not offer another better matching candidate so we can either take what we have or declare J2576 as lost Jonckheere object. Acknowledgements The following tools and resources have been used for this research: AAVSO APASS (via the UCAC4 catalog) AAVSO VPhot Aladin Sky Atlas v8.0 Astrometrica v AstroPlanner v2.2 itelescope it24 & it27 MaxIm DL6 v6.08 SIMBAD, VizieR, UCAC4, URAT1, GAIA UCAC4 catalog via the University of Heidelberg website and directly from USNO DVD Washington Double Star Catalog References Buchheim, Robert 2008, CCD Double-Star Measurements at Altimira Observatory in 2007, Journal of Double Star Observations, Vol. 4 No. 1 Page 28 Greaney, Michael 2012, "Some Useful Formulae" in R.W. Argyle, Observing and Measuring Visual Double Stars, 2nd Edition 2012, Chapter 25, Page 359 Heintz, W.D. 1990, Observations of double stars and new pairs. XIV. Astrophysical Journal Supplement Series Vol. 74, p Knapp, Wilfried; Nanson, John 2016, Jonckheere Double Star Photometry Part I: Cyg, Journal of Double Star Observing, Vol. 12 No 2 pp. nn-mm Knapp, Wilfried 2016, Jonckheere Double Star Photometry Part II: Del, Journal of Double Star Observing, Vol. 12 No 3 pp. nn-mm