Intrinsic Variability of beta Lyrae Observed With a Digital SLR Camera (Abstract)

Volume 37 number 2 (2009)

Donald F. Collins

Anesh Prasai

Abstract

(Abstract only) We show that a digital SLR (DSLR) camera (Canon XTi) follows a linear response to light exposure when images are saved in raw format. We also demonstrate its usefulness for photometry of bright variable stars such as beta Lyrae (4.2m–3.2m) and other bright variable stars. Mounted on a stationary tripod and fitted with a standard zoom lens set at 55 mm FL at f/5.6, this camera obtains reasonably precise photometry (± 0.02m) for bright stars. Imaging bright stars with a telescope and CCD imaging detector is hampered by rapid saturation and the lack of suitable bright comparison stars in the field of view. Subtracting the average brightness for beta Lyrae, we can easily detect the intrinsic variability of beta Lyrae (15%) with a period about 280 days. More such observations are requested to learn more about the period and phase of the intrinsic variability of beta Lyrae.