Stellar Photometry With DSLR: Benchmark of Two Color Correction Techniques Toward Johnson's VJ and Tycho VT

Abstract

DSLRs are now routinely used for measuring the V magnitude of stars through their G channel output. This requires a transformation to Johnson V, using a correction based on the catalogue (B-V) color indices of the stars. This paper reviews the responses of the involved passbands and proposes an alternate solution using a synthetic filter made by combining the three RGB DSLR channels. The assessment of the two techniques through experimentation being uncertain, we have chosen to use a computer simulation instead. This simulation combines the measured spectral responses of the DSLR channels, the atmospheric reddening, and star spectra from the Pickles library.