Precision multi-band photometry with a DSLR camera

TL;DR

This study demonstrates that consumer-grade DSLR cameras, specifically the Canon EOS 60D, can achieve sufficient precision in multi-band photometry to detect transiting hot Jupiters, offering a cost-effective alternative to CCDs.

Contribution

The paper shows that DSLR cameras can be integrated into exoplanet surveys to perform precise multi-band photometry, expanding accessible options for astronomical observations.

Findings

Achieved median absolute deviation of 4.6 mmag in combined color channels.

Measured over 1000 stars with better than 10 mmag precision.

Detected known transiting hot Jupiter KELT-3b in the survey field.

Abstract

Ground-based exoplanet surveys such as SuperWASP, HATNet and KELT have discovered close to two hundred transiting extrasolar planets in the past several years. The strategy of these surveys is to look at a large field of view and measure the brightnesses of its bright stars to around half a percent per point precision, which is adequate for detecting hot Jupiters. Typically, these surveys use CCD detectors to achieve high precision photometry. These CCDs, however, are expensive relative to other consumer-grade optical imaging devices, such as digital single-lens reflex cameras (DSLRs). We look at the possibility of using a digital single-lens reflex camera for precision photometry. Specifically, we used a Canon EOS 60D camera that records light in 3 colors simultaneously. The DSLR was integrated into the HATNet survey and collected observations for a month, after which photometry was extracted for 6600 stars in a selected stellar field. We found that the DSLR achieves a best-case median absolute deviation (MAD) of 4.6 mmag per 180 s exposure when the DSLR color channels are combined, and 1000 stars are measured to better than 10 mmag (1%). Also, we achieve 10\,mmag or better photometry in the individual colors. This is good enough to detect transiting hot Jupiters. We performed a candidate search on all stars and found four candidates, one of which is KELT-3b, the only known transiting hot Jupiter in our selected field. We conclude that the Canon 60D is a cheap, lightweight device capable of useful photometry in multiple colors.