Flat-Fielding for CCDs in AAVSO Observations, I

Volume 27 number 1 (1999)

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Gary P. Emerson

Stephen J. Little

Center for Astrophysics and

Abstract

Flat-field correction for CCD chips is necessary to correct for the relative sensitivity to light of each pixel in the array as well as non-uniformities in the focal plane of the telescope + filter combination. This has been a serious issue for AAVSO CCD observers. Each observer tends to have a different method of performing flat-fielding, and even in the professional astronomical ranks there is no agreement as to how flat-fields should be obtained. We present a simple method that can be used at any time of day or night to make an accurate flat-field for CCD observing.