TFIT: A Photometry Package for Mixed-Resolution Datasets

摘要

TFIT is a software package for measuring relative galaxy photometry between imaging data sets with different angular resolutions,such as the Hubble ACS and Spitzer IRAC images taken for the GreatObservatories Origins Deep Survey (GOODS). It combines prior informa-tion about spatial position and morphology obtained from high angularresolution images with PSF information about both images to constructobject templates, which it then fits to a lower-resolution image of thesame field. Simulations demonstrate that this technique improves accu-racy in uncrowded fields, with performance holding steady as crowding increases and object separation decreases to 1.5 PSF FWHM: outper-forming SExtractor by a factor of two. Photometry is also measured,with < 10% degradation, for objects that SExtractor fails to deblend.On real GOODS data, TFIT produces results that are consistent witha traditional PSF subtraction method. TFIT is implemented in Pythonand C++.