Measuring the lives of the brightest variable stars.
What We Do
While CCD cameras have revolutionized amateur photometry, camera systems struggle with very bright stars like Betelgeuse. AAVSO PEP concentrates on stars brighter than magnitude 6 using instruments known as photometers that sample one star at a time through the telescope. Though photometers are not as versatile as cameras they are much simpler to use. New observers can acquire high-quality data without extensive training.
How We Do It
PEP is a very “hands-on” technique. For even a single target, making a measurement involves cycling the telescope between the variable and a reference star, centering the stars in an eyepiece each time, and recording repeated brightness readings. It is a slow process but it yields good results. It does mean, however, that the observer is out in the open with the telescope, not seated in the comfy indoors. We supply spreadsheets for people to process their raw data and prepare it for upload to the AAVSO.
Training materials are available, and we can mentor newcomers in the details of PEP. The SIG has group projects where you can collaborate with other observers and compare your work with theirs. We have quarterly online meetings where the latest news is shared.
Is It Right for Me?
Level: Easy. PEP is a good starting place for beginning observers and a satisfying niche for experienced observers who like bright stars.
Equipment: A telescope on a semi-permanent equatorial mount is pretty much required. Work can be done with a short-focus refractor of 130mm aperture or a Cassegrain reflector of 200mm. Larger instruments will offer more observing opportunities. Newtonian reflectors are not suitable. A photometer with at least a Johnson V filter is needed.
Observing Requirements: Bright skies are not a barrier. Many PEP targets are bright enough to be observed even from suburban locations. Each observing session usually takes one to two hours, depending on the number of stars observed.
Additional Considerations: Photoelectric photometers are now difficult to come by, so speaking with the section leader for assistance is strongly encouraged.