Precision multi-band photometry with a DSLR

Abstract

Ground-based exoplanet surveys such as HATNet, SuperWASP, and KELT have discovered over a hundred planets in the past several years. The strategy of these surveys is to look at a large eld of view and measure the brightnesses of its bright stars to around half a percent accuracy, which is accurate enough to detect hot Jupiters. Typically, these surveys use high-quality CCDs to get very accurate photometry. These CCDs, unfortunately, are very expensive. We look at the possibility of using a DSLR{specifically a Canon EOS 60D{for precision photometry. The DSLR was integrated into HATNet and collected observations for a month, after which photometry was extracted for 6500 stars. We found that the DSLR achieves a best-case median-median deviation of 4 mmag when the colors are combined, and over 1100 stars are measured to better than 10 mmag. We achieve 10 mmag or better for photometry in individual colors. This is good enough to detect a large fraction of hot Jupiters. We conclude that the 60D is a cheap, lightweight device capable of useful photometry in multiple colors.