Maximizing Precision of Variable Star Photometry with Digital Cameras in Suburban Environments

Abstract

Photometry is the measure of the brightness of an object. When making such measurements on stars, it is done is units of magnitude, which is on a logarithmic scale with a base of ~2.512. Variable star photometry using a commercially available digital camera is not going to be as accurate and precise as equipment used by astronomers, and because of the logarithmic scale of magnitude used, determining how much of an effect different error reduction strategies have is not straightforward, and is best done experimentally. My research is conducting photometry on variable stars (changing brightness) with a digital camera, and testing both the limits in terms of how faint of a star can be reliably detected, but also which methods for recording and processing data have an effect on the measurement in the first four digits of a photometric measurement. Examples include whether taking dark frames, in which a picture of darkness is taken with the same camera setting as the night sky image, and subtracted from the first image to reduce in-camera noise, has an effect, and if so, how many dark frames before no significant change is seen. Other error reduction strategies I’m examining include accounting for the drop off in brightness towards the edges of an image due to camera optics, canceling out the brightness of the sky to correct for light pollution, and calibrating the target star against other known stars

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