Developing A Visual Variable Star Observing Program

Transcription

1 Developing A Visual Variable Star Observing Program An AAVSO course for the Carolyn Hurless Online Institute for Continuing Education in Astronomy (CHOICE) This is copyrighted material meant only for official enrollees in this online course. Do not share this document with others. Please do not quote from it without prior permission from the AAVSO.

2 Table of Contents 1- Introduction 2- Course Description and Requirements 3- Program Building Triad 4- The Fun Factor 5- Questions for Investigation and Discussion 6- Where Do Observer Codes Come From? 7- A Shocking Truth 8- How To Use VSX 9- How to Use The LPV Bulletin 10- Other Resources 11- Sample Profile 12- Sample Observing Program 13- Acknowledgements

3 1 Introduction We will always need visual observers. - Janet Mattei For the first fifty years of the AAVSO s history if you wanted to observe variable stars your choices were limited to a few hundred long period variables, U Gem, SS Cyg, R CrB and a few other novae or unusual stars that had caught people s attention. Those were the only stars AAVSO observers had ever observed. The number of charts available was a limiting factor also. This was limited in great part by the difficulty in making and distributing standardized charts as well as obtaining the photometry with which to create a sequence of comparison stars. Creating a visual program wasn t that difficult. You simply selected from the list of stars in the AAVSO program or observed whichever stars headquarters sent you charts to observe! This began to change in the 60 s and 70 s with Clint Ford and Charles Scovil expanding the number and type of stars in the program and creating charts for them. Theories of stellar composition, evolution and variability began to catch up to the nearly 100 years of observations that existed at this point, adding to the diversity of variable types to study and the need for more data. In the 90 s, Scovil began creating computerized charts and in the late 90 s into the 21 st century these charts became available online and demand for more stars, more charts and more variety exploded with the Internet age. When I first started observing, I started with all the stars in David Levy s book A Guide to Variable Stars. I used everything I could lay my hands on. Old "micro-dot" charts, preliminary charts, and a few of the new computer generated charts that I would have to hold upside-down and shine a flashlight through to match the view in the eyepiece of my Schmidt-Cassegrain telescope. In 1999, not everything in the chart catalog was online yet, and only a small percentage of the charts were available as reversed charts for use with a Schmidt-Cassegrain. It wasn t long before my observing program simply became all the stars with available reverse charts. As I became more experienced, and could observe more stars per hour per night, I found I needed to expand my program beyond the couple hundred mostly LPV stars in it or I would run out of things to look at after a spell of a few clear nights. You should only observe long period stars twice a month- once per week at most. So I needed to observe hundreds and hundreds of LPVs or I would beat the sky and run out of things to observe. It wasn t long before I realized if I observed cataclysmic variables I could observe the same ones night after night. I could observe 100 stars tonight and observe the same 100 stars tomorrow and that was a good thing, because my chances of detecting CVs in outburst were directly proportional to the number of stars I could observe in a given night.

4 2 It actually became a sort of competition between the most prolific observers in the world to be the first one to catch a star in outburst, especially the rarely outbursting ones, and have your name listed in the daily news flashes. I loved the recognition and the competition. I decided I wanted to be the Michael Jordan of CV observers and finally settled on an observing program- every CV I could find with a maximum magnitude of 15 or brighter. My choices of program stars had been guided by a David Levy book, then by the availability of charts suitable to my telescope, and finally by my ego. I had a lot of fun; in fact I went a little crazy, making 10,000 observations a year a couple years in a row. But were my mostly less than observations, really valuable? I had other questions. Would I be serving science better if I observed fewer stars more frequently, or a different type of star, or stars I could actually make positive detections and estimates for? What stars did the AAVSO want me to observe? What stars did professional astronomers want data for? The unwritten policy of the AAVSO was to NOT provide guidance or steer observers toward specific stars or one type of star, because no one knew what the next big thing would be, or what might be discovered if everyone just observed everything they could. Had I known then what I know now, I might have approached the whole process differently. When the plans for the observer certification program developed to the point that it was time to pick the first subject for the visual observing program, I knew exactly what I wanted to do. I wanted to help observers make informed decisions and help answer the questions I knew they too would eventually ask. Things have changed dramatically since The AAVSO does have suggested programs of stars and scientific justifications for wanting observers to observe them. The resources available to observers now are light years ahead of what we had before the turn of the century. VSX, the Bulletin, the light curve generator, quick look, observing sections, dozens of web pages devoted to visual observing, and a chart plotter that will plot thousands of charts with AAVSO visual sequences- you people don t know how good you have it. Building a scientifically valuable, satisfying, challenging and fun visual program will be easier than it ever has been before. The last time I spoke to Janet Mattei was in December 2003, just before Christmas. She called me at home from her hospital bed. In the course of our conversation about charts and CCD observers she suddenly stopped and said, You are an excellent visual observer, Mike. Don t ever stop. We will always need visual observers. I ll never forget that. Three months later, Janet was gone. That is why I continue to make visual observations even though I have a telescope and CCD and collect data from robotic telescopes. I do it for Janet, because it is fun, and because I have finally figured out which stars I can observe that the visual data are most likely to prove valuable scientifically.

5 3 Course Description Requirements To successfully complete this section of the CHOICE in Astronomy, Visual Observing Certification you must provide in writing, two documents. 1- A complete observer profile (a sample is provided) 2- A list of stars appropriate for your primary observing equipment, observing site and conditions, frequency of observing sessions, scientific merit and fun factor (a sample is provided). Duration The course will last four weeks. You may submit your profiles and programs as soon as you like. By the end of the second week you must submit your first draft profile and observing program. The cohort will comment on them as part of their learning experience. You will use whatever comments you feel are useful to edit your work and submit the final version by the end of the fourth week. Evaluation You will be evaluated on your participation in discussions (both frequency and content) and your final profile and program. You cannot pass if you do not participate in discussions.

6 4 Program Building Triad Scientific Value It is important to understand the value of visual observations and which stars and what areas of research hold the most promise for visual observers to make a valuable contribution to science. We will consider the impact of CCDs and surveys on the value of visual observations. We need to take a realistic look around and assess the current and likely future landscape of variable star research to find answers to these questions. We will also look at the programs and opportunities provided by or recommended by the AAVSO. Profile Related What you ll be able to observe is determined largely by your observing site, sky conditions, how often you can go out and how long you can stay out to observe, as much as by the size and type of equipment you use. Your experience comes into play here also. How fast can you go from one target to the next? Are you organized and prepared? Do you know the fields? Do you know how to eek out the faintest stars from your equipment? We ll explore how your personal experience and situation impacts the selection of stars you observe. Equipment Related Knowing the limitations and potential of your equipment is important. How faint can you see on an average night in your telescope? What are the brightest stars you should attempt to observe in your telescope? Is there a limit? You don t need to know everything about telescopes and eyepieces. You just need to know everything you can about your telescope and eyepieces. The Fun Factor If you don t think this is fun you won t do it. So what makes it fun for you? Is it the challenge? Is it being outside and in touch with the Universe? Are there some stars you like to observe just for the fun of it? How serious do we need to be? Is any of this important? Can we take this seriously, contribute to science and still have fun? Believe it or not, this makes a difference. We want you to be successful, happy and productive. If this isn t fun for you, you won t be.

7 5 Questions for Investigation and Discussion (These topics will be covered in the course online forum) General Questions 1- Why do we want to know your observer code? 2- Why do you observe variable stars? 3- Is it important to you that your data be used to contribute to science? Scientific Value 1- What areas of the sky are fruitful for visual observers to continue observing in spite of the encroachment of automated all sky surveys? 2- What do you think is typically more scientifically valuable? 3 observations each of 100 different stars in a year, or 100 observations of 3 stars in a year? 3- Are fainter than observations scientifically valuable? 4- Should you pick stars for which there is little or no data in the AAVSO database, or should you pick stars for which there is a lot of data? Why? 5- What are some reasons why observing only stars in the LPV Bulletin is NOT a good idea? 6- Why would circumpolar variables be considered to be prime candidates for your program? Profile Related 1- How does your observing site impact the stars you pick to observe? 2- How can we use your location (latitude and longitude) to evaluate your choices of program stars? 3- How does light pollution affect your selections? 4- How does your typical naked eye limiting magnitude relate to what you will see in the eyepiece? How will this affect your selections? 5- How can a blocked horizon actually be beneficial?

8 6 6- What impact does your frequency of observations have on your potential selections of program stars? 7- If you can observe 10 stars per night, twice a week, on average; how many stars should be in your program? 8- If you start out with 200 stars in your program, will you ever need to observe more stars? Why? Why not? Equipment Related Between these three types of instruments- Dobsonian reflector, German Equatorial Mounted refractor without a star diagonal, Fork Mounted Schmidt-Cassegrain with star diagonal: 1- What kind of telescope is easiest to use to observe near the celestial pole? Which type do you think would be the most difficult? Why? 2- What kind of telescope is most comfortable to use to observe directly overhead? Which type do you think would be the most difficult? Why? 3- What kind of telescope is easiest to use to observe near the horizon? Which type do you think would be the most difficult? Why? 4- What is the typical limiting magnitude of your primary observing instrument? 5- Should you observe stars that get fainter than your limiting magnitude? 6- How bright is too bright for your telescope? Is there a limit? Fun Factor 1- Is it okay to observe some stars just because you think they are fun, even if there is no scientific justification for observing them? 2- What percentage of your program should be fun things you observe just for the enjoyment?

9 7 Where Do Observer Codes Come From? Since the very beginning, AAVSO observers have been assigned observer codes. These letter combinations are used to identify the individuals who have submitted data to the database for a number of reasons. For better or worse, once you have been assigned an observer code it is yours forever. It was interesting to me to find out some of the stories behind the assignments of these codes. For example, how did I end up with the code SXN? Why do RASNZ observers nearly all have an X at their end of their codes? Why do new observers have four letter codes now? The first observers were assigned one letter observing codes. You may know some of the famous ones. Leslie Peltier was P, William Tyler Olcott was O, Giovanni Lacchini was L. The letter C was assigned to Leon Campbell in recent years for historical archiving purposes. Who got the rest of the alphabet, and who were these people? Do you know any of them? Luverne Armfield was assigned the letter A; Ferdinand Hartmann H; Walter Inglis -I; Eugene H. Jones J; Sigeru Kanda K; Franklin Marsh M; Henry Raphael R; Franklin Smith S; and H. W. Vrooman V. Once those were essentially used up (there are some that weren't used; Q, U, Z and X for example) they began assigning two letter codes. We still have active observers who have older two letter codes. Some historical observers were, Clinton Ford -FD, Ed Oravec- OV, Wayne Lowder- LX, Carolyn Hurless- HR. Some present-day observers who are still active are Albert Jones- JA; Marv Baldwin- BM; and David Williams- WI. All these codes were assigned by headquarters. The basic idea was to use the first letter of the last name and then the first letters of the first names. When these began to run out they began to assign three letter codes and got a little more creative. They were running out of letter combinations for "S" when I joined in 1998, so I didn't get SMA. That was assigned to some guy named Martin Schneider who made 13 observations between 1966 and So, I ended up with SXN. Even the X's started getting used up near the end of the line! For the last three decades this job of assigning codes fell to Elizabeth Waagen. She was careful to try to not create words that would be inappropriate, even taking foreign languages into account as much as possible. I did assign the letters SEX to a 19th century archival observer recently, Elizabeth said, Julius F. Schmidt is probably turning over in his grave. Interestingly, almost all the RASNZ observers ended up with an X at the end of their codes. This happened because they already had two letter codes in the RASNZ, but when

10 8 we began to import their data we needed to assign them new AAVSO codes. So, for the most part they ended up with their old two-letter code and an additional X at the end. Rod Stubbings SR, became SRX. Andrew Pearce became PEX, Peter Nelson became NLX, and so on. I like to think of the codes as a secret handshake kind of deal. It s something only we observers in the AAVSO know or care about, and it becomes even more exclusive with time, because it s the active observers whose initials become familiar to you. When you become one of the active observers in the AAVSO you become a member of a special and relatively small clique of people. After a while we all recognize each other's observer codes when they show up in MyNewsFlash the CVnet Circular or other reports. I ve grown used to my initials. My wife says they stand for SeXy Nerd. I can live with that. Mike (SXN) Simonsen A Shocking Truth I'm going to let you in on a shocking truth. There are not that many variable star observers in the world. Even worse, only a fraction of those are visual observers. Now here's an even scarier truth. The trend is that there are less and less of us all the time. So while it may have been true in the past to say, "if I only do three observations of R Cyg this year that's okay, because there are lots of other people observing it, and they will fill in the light curve", it just ain't so. There are fewer observers submitting visual data now than there were five years ago. So one thing the AAVSO has decided to do is to try and focus the efforts of the remaining visual observers on those stars for which we have excellent long-term data. We're calling these "Legacy Stars". So as a general rule, more regular observations of fewer stars is more valuable nowadays than sporadically hitting hundreds of stars in a catch as catch can manner. If you want to observe stars that no one else is observing, fine. You can always do what you want. But if you want your observations to have a statistically better chance of being useful in the long run and contributing to science, observe your private project stars enough to build up a meaningful light curve of your own data, or contribute to the efforts of other observers like you continuing the tradition and fun of joining together their efforts to create a useful extended light curve.

11 9 How to use VSX Variable Star Index (VSX) We will use VSX as a powerful tool for finding stars with which to build your program. Name The Name field can be used to locate a specific star within VSX by catalog designation, or to view a list of stars whose designations are similar to a supplied partial name. To find a single star, enter the complete catalog designation into this field and click Search. To perform a wildcard search, use the percentage sign character (%) at the beginning and/or end of a partial name. For example, entering "%Per" will return a list of all GCVS variable stars discovered within the constellation Perseus. Entering "NSV %" will return a list of all the variables in the NSV catalog. To retrieve the coordinates of any named object (even those not contained in VSX), enter a name recognized by the SIMBAD database and click Get Coordinates. The object's coordinates will be entered into the Position field (and, if need be, the Search form will expand automatically to reveal the Position field). A radius search can then be performed using those coordinates. In addition, any search may be limited to only those stars within the boundaries of a particular constellation by selecting one from the Const. drop-down menu. This menu is not intended to specify part of the name of any object, but instead merely filters the results so that only those stars found within the area of the selected constellation are returned. Position The Position field accepts a set of equatorial J coordinates and permits searches of the VSX database for objects having positions within the circle or box whose center is defined as the given coordinates and whose dimensions are described by the Size value. Indicate by selecting the appropriate radio button whether the coordinates supplied are in Sexagesimal format (HH MM SS.ss +DD MM SS.s), or Decimal degrees. Enter a radius distance or box width in the Size field and select the relevant units from the drop-down menu. Select either Radius or Box size to indicate the geometry for your search area. When performing radius searches, be sure to select "Angular sep." from the Order by drop-down menu at the bottom of this form so that the search results are sorted according to distance from the supplied position. For your convenience, the Search form automatically makes this selection for you whenever you enter anything into the Position field.

12 10 Magnitude Filters By entering values into the Max mag. and/or Min mag. fields, searches can be performed to locate variable objects within VSX whose observed and cataloged magnitude ranges are within those specified. Supply both an upper and lower extent for a magnitude range in order to include objects with maximum and/or minimum magnitudes between and including those given. Enter only an upper (brightest) value to locate magnitudes equal to or fainter than that value. Enter only a lower (faintest) value to locate magnitudes equal to or brighter than that value. If desired, both maximum and minimum magnitude ranges or limits may be specified to create bracketed or donut result sets. Variability Type By entering a value into the Var. type field, searches can be performed to locate stars of variable types equal or similar to the type abbreviation provided. Variable types that work best in this field are those that follow the GCVS standard, although other non-gcvs catalog entries in the VSX database use other types and abbreviations specific to those catalogs. Wildcard searches are performed by inserting the wildcard character (%) at the appropriate positions. More information may be found by clicking on the (?) help buttons on the VSX interface. How to use the LPV Bulletin AAVSO Bulletin - Predicted Dates of Maxima and Minima of Long Period Variables The AAVSO Bulletin contains predicted dates of maxima and minima of long period variables, and shows when a variable will be rising to maximum, fading from maximum, brighter than magnitude 11.0, and fainter than magnitude The period covered is January through February. You can access the Bulletin in the following ways: Fixed format: schematic file (.pdf) covering the entire sky for the entire 14 months the Bulletin covers; text file covering the entire sky for all 14 months containing the information in comma-separated format (.CSV) suitable for loading into a spreadsheet; text file (CSV) sorted in order of increasing number of observations; replaces Stars in Need of Observations lists included with earlier Bulletins Customizable options: Using the Bulletin Generator, you can customize the Bulletin to suit your observing/research needs. You can select: all stars, a specific star, or a list of stars; the whole year or a single month; all constellations or a particular constellation; the whole sky or a range of Right Ascension and/or Declination;

13 11 in the schematic html file, the colors used to signify whether a star is brighter than visual magnitude 11.0 or fainter than On the line for a given star, you can click on the link to the AAVSO Light Curve Generator to see the star's recent behavior, to the International Variable Star Index (VSX) to see astronomical information on the star, or to the table of AAVSO observed maxima and minima for the star. The N field (number of observations during calendar year 2010) tells you if a star is well covered or needs more observations. For more detail and examples see: Other Resources AAVSO Visual Observing Manual Introduction, Chapter 1 and Chapter 5 Observer Main Page Suggested Stars for Visual Observers LPV Section Websitehttps://sites.google.com/site/aavsolpvsection/lpv-files AAVSO Legacy, Program and Binocular Variable Lists LPV Section Forumhttp:// The Usefulness of Visual Observations CVnet CV Circular Lists of CVs with magnitudes, types and activity levels CVnet-CVs for Visual Observers Small Scope Sampler AAVSO Publications- Observer Notifications Alert Notices, Special Notices, MyNewsFlash Telescopic Limiting Magnitude Calculator

14 12 Sample Profile Name: Mike Simonsen Observer Code: SXN Site: Permanent domed observatory, relatively dark sky rural site Location: Imlay City, MI USA Latitude and Longitude: N 42 59' ", W 83 6' " Limiting Visual Magnitude: 5 Horizon: Clear N, E and W. Trees to the south block up to degrees from the horizon. Weather/Seasonal factors: Winters are mostly cloudy and brutally cold, spring is often cloudy and rainy, summer nights are short and hazy, fall is excellent with many long clear nights. Other factors: On average, 100 clear or partly clear nights per year. Perhaps 10 photometric nights per year. Frequency of observations: 2x/week, 100x/year Nightly rate: observations per night Experience: 12 years visual observing, over 55,000 visual observations. I am the coordinator of the Mentor Program, CV Section, LPV Section, and Charts and Sequence team for the AAVSO. Equipment Telescope: 12 LX200 GPS Eyepieces: TeleVue Nagler, 12mm, 17mm, Radian 10mm, Meade Plossls, 32mm, 26mm. Other: 50mm finder scope and 80mm refractor, mirror-reverse (same as telescope) for bright stars 9-5V. Primary Program- LPVs ranging from 9-16 th magnitude, a few CVs and RCBs that can be seen most of the time in their cycle with my telescope, and a few oddball stars just for fun. Secondary Program- Robotic telescope (Sierra Stars Observatory 0.61m) CCD observations of LPVs too faint to see visually each month.

15 13 Sample Observing Program NAME CON RA (2000) DEC (2000) TYPE MAX MIN PERIOD (D) R Aur M W Aur M S Aur M RU Aur M SZ Aur M U Aur M RS Aur SRA VY Aur M RR Aur M X Aur M ST Aur M V Aur M GO Aur M GQ Aur M HT Aur M VX Aur M SV And M X And M T And M R And M TU And M RW And M V And M RR And M U And M UZ And M Y And M W And M SZ And M R Aql M W Aql M RT Aql M RV Aql M X Aql M SY Aql M Z Aql M R Ari M T Ari M U Ari M Z Boo M S Boo M

16 14 RR Boo M U Boo SRB X Cam M R Cam M IW Cas M Y Cas M SS Cas M T Cas M UW Cas M TY Cas M U Cas M RV Cas M W Cas M VZ Cas M S Cas M X Cas M V Cas M Z Cas M RR Cas M WY Cas M R Cas M Y Cep M Z Cep M RR Cep M T Cep M S Cep M S Cet M Z Cet M R Cet M X Cet M V CMi M R CMi M WX CMi M S CMi M T CMi M U CMi M VX CMi M ST Cnc M RR Cnc M SU Cnc M SZ Cnc M V Cnc M U Cnc M UY Cnc M W Cnc M R Com M

17 15 S CrB M R CrB RCB X CrB M Z CrB M W CrB M TY Cyg M R Cyg M BG Cyg M RT Cyg M TU Cyg M Khi Cyg M Z Cyg M S Cyg M SX Cyg M WX Cyg M U Cyg M ST Cyg M V Cyg M WY Cyg M R Del M Z Del M S Del M T Del M V Del M X Del M Y Dra M R Dra M T Dra M V Dra M W Dra M X Dra M U Dra M ZZ Gem M CD Gem M VV Gem M UY Gem M X Gem M IT Gem M RS Gem SRB R Gem M AM Gem M WZ Gem M XX Gem M V Gem M ST Gem M S Gem M

18 16 BE Gem M T Gem M XY Gem M BP Gem M R Her M RU Her M SS Her M W Her M S Her M RV Her M SY Her M RT Her M RS Her M RY Her M T Her M TV Her M SV Her M R Leo M V Leo M S Leo M R LMi M S LMi M RW Lr M S Lyn M R Lyn M W Lyr M TV Lyr M TW Lyr M RY Lyr M RX Lyr M Z Lyr M RT Lyr M WZ Lyr M AB Lyr M V Lyr M TY Lyr M UV Lyr M UW Lyr M RS Lyr M S Lyr M SS Lyr M EL Lyr M U Lyr M RU Lyr M AN Lyr M V Mon M

19 17 SY Mon M ST Mon M Y Mon M BI Mon M RS Mon M RR Mon M TT Mon M RX Mon M BC Mon M EP Ori M FG Ori M R Ori M V Ori M FN Ori M S Ori M BK Ori M RR Ori M V345 Ori M RZ Per M U Per M RR Per M DY Per RCB AI Per M R Per M UY Tau M AK Tau M TZ Tau M VX Tau M R Tau M S Tau M RX Tau M V Tau M YY Tau M SU Tau RCB Z Tau M T UMa M RS UMa M T UMi M U UMi M S UMi M SV Vir M SU Vir M T Vir M Y Vir M R Vir M U Vir M

20 18 RV Vir M V Vir M S Vir M SY Vir M RR Vir M Z Vir M RS Vir M RZ Vul Unique R Vul M

21 19 Acknowledgements Carolyn J. Hurless Carolyn J. Hurless was the most active and prolific woman observer in the history of the AAVSO, with 78,876 observations in the International Database. But that only scratches the surface of this remarkable woman s life and career as an AAVSO observer, councilor, officer, mentor and ambassador. Born in Lima, Ohio, November 24, 1934, Carolyn became interested in astronomy at the age of 13 through her love of science fiction. As a young woman, she was invited to join the Lima Astronomy Club, when President Herbert Speer found her name on the borrowers cards of people who had checked out astronomy books from the public library. Shortly after that, she decided to make her own 8-inch reflector with the guidance of fellow astronomy club members. When the initial grinding was done, Carolyn found that in her excitement she had hogged out a short focus mirror of f/4, instead of the typical f/8 or f/9 scope most were making at the time. In the end it turned out to be a fine instrument. In fact the short tube length gave her, as she described it, a feminine telescope, easily transported and set up for observing. Most of her observations were made with this telescope and she never felt the need to upgrade to something else. Carolyn learned variable star observing from legendary AAVSO observer and fellow Ohioan, Leslie Peltier. Carolyn would make the trip to Delphos, Ohio to observe faint inner sanctum stars with Peltier s 12-inch refractor nearly every week during their lifelong friendship. She was more than happy to pay it forward by mentoring other newcomers and sharing her enthusiasm with other variable star observers around the world.

22 20 One way she managed to do that was by publishing the informal monthly newsletter Variable Views in which she shared ideas about astronomy, stories of variable stars and amateur astronomers and humorous notes about her own experiences. She started the newsletter at her own expense and published it for 22 consecutive years. Carolyn invited her Variable Views readers to summer gatherings each year at Leslie Peltier s home where she was able to inspire young people with her love of the stars and observing. She managed to reach out and touch people across international boundaries also, in a time when this was not easy to do. She sponsored a Czechoslovakian observer, Jaroslav Kruta, to AAVSO membership. Through persistent correspondence, mainly tape recordings, she taught Jaroslav English, and was able to introduce several other AAVSO members to him by arranging for them to meet when they visited Czechoslovakia. Besides sharing her enthusiasm for astronomy with the public, she managed to hold down a full-time position as a music teacher, inspiring countless young musicians along the way. The Carolyn Hurless Online Institute for Continuing Education is proud to carry on in the tradition of this remarkable woman. This document was written by Mike Simonsen, with contributions from Arne Henden Aaron Price, Matthew Templeton, and Christopher Watson.