Alt-Az Initiative


Alt-AZ Initiative
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Double Star Research

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What are double stars? Why do we study them? What measurements do we make? What equipment is required? What do we do with the data obtained?

All of these questions will be answered if you choose to be part of one of the double star astrometry groups at Pine Mountain Observatory this summer. The workshop will be held August 5-8, 2010. Work in these groups will be devoted to scientific measurements of double or multiple star systems. Over 50% of the 6000 naked eye visible stars in the sky have at least one, or more, companion stars associated with it. We will measure the apparent distance between these stars and their position relative to Polaris, the celestial pole star. This information will eventually result, in some cases, in the determination of the orbital period of the system.

We will show that double star studies can be made with fairly simple telescopes on either equatorial or alt-az mounts. Tracking motors are usually required. The telescope is equipped with an illuminated reticle astrometric eyepiece that is used to make the measurements. Math skills are minimal. All formulas are carefully explained and examples given. Computer knowledge of spread sheets (like Excel) and word processing programs (like Word) are fundamental to doing these studies. A detailed presentation will be given upon your arrival of the necessary observational techniques and data processing required.

Once calibration and observations have been carried out, and we get some sleep, we will devote the rest of the time to reducing and processing the data. As a group, we will prepare a power point presentation of our results to be presented to all of the attendees at the workshop. This will include our purpose, equipment used, systems studied, observation results, what you gained from the experience and conclusions. This summary will be used as a basis for a paper in the Journal of Double Star Observations ( 

Thomas G. Frey
PI, Astrometry
PMO, 2010

You are encouraged to consult a few of the following references before arriving to get some background information on double stars:

Argyle, Robert, Observing and Measuring Visual Double Stars, Springer, London, 2004.
Haas, Sissy,
Double Stars for Small Telescopes, Sky Publishing, Cambridge, MA, 2006.
Teague, Thomas, 2000, Sky and Telescope, July, 112-117.
Frey, Thomas G., Spring 2008, Journal of Double Star Observations, 3(2), p. 59-65.
Arnold, Dave, Winter 2006, Journal of Double Star Observations, 2(1), p. 13-20.
Genet, Russell,, Small Telescopes and Astronomical Research, Collins Foundation
         Press, Santa Margarita, CA, 2010:
         Chapter   9: Double Stars (Robert Argyle)
         Chapter 10: Visual Double Star Measurements with Equatorial and
                            Alt-Azimuth Telescopes  (Thomas Frey, et al)
         Chapter 11: Considering Proper Motion in the Analysis of
                            Visual Double Star Observations (Dave Arnold)
         Chapter 12: All about the Journal of Double Star Observations (R. Kent Clark)
         Chapter 18: Pine Mt. Observatory Summer Research Workshop (Russ Genet, et al)
         Chapter 23: Double Star Measurements with a Three-Inch Tasco Telescope
                            (Darrel Grisham, et al)

In addition, the following papers will provide further important information:

Word Documents:
Neglected Double Stars I.doc
Neglected double Stars II.doc
Workshop Goals, PMO.doc
Writing Research Paper, Double Stars, PMO.doc
Key Ideas PMO Double Star Power Point.doc
Possible triple star systems.doc
Power Point:
Calibration Stars for Double Stars.ppt
Data Sheet, Double Stars.xls
Known Double Stars PMO.xls
T. Frey, JDSO,Double Stars, Alt-Az.pdf
T. Frey,JDSO, ARY52,PMO .pdf
D. Arnold, JDSO, #20.pdf
Conversion Formula, JDSO.pdf

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