A maximum-likelihood method for improving faint source flux and color estimates

摘要

Flux estimates for faint sources or transients are systematically biased highbecause there are far more truly faint sources than bright. Corrections whichaccount for this effect are presented as a function of signal-to-noise ratioand the (true) slope of the faint-source number-flux relation. The correctionsdepend on the source being originally identified in the image in which it isbeing photometered. If a source has been identified in other data, thecorrections are different; a prescription for calculating the corrections ispresented. Implications of these corrections for analyses of surveys arediscussed; the most important is that sources identified at signal-to-noiseratios of four or less are practically useless.