Back to Volume
Paper: Deconvolution as a Tool for Improved Crowded-Field Photometry with HST
Volume: 216, Astronomical Data Analysis Software and Systems IX
Page: 595
Authors: Butler, R.
Abstract: The conventional approach to performing crowded-field photometry, whether with ground- or space-based telescopes, is to use either PSF-fitting alone or some hybrid method of aperture photometry on neighbor-subtracted images, which also requires a PSF-fitting step. I show here that in very crowded fields, such as the cores of globular clusters, aperture photometry of sub-sampled-deconvolved HST/WFPC2 images gives statistically better results than such conventional reductions of the original data with DAOPHOT-II. Perhaps more importantly, the deconvolved images also provide the basis for improved star detection, using otherwise conventional means. The technique succeeds by exploiting the nature of the HST/WFPC2 PSF: under-sampled, spatially varying and with high-frequency structure in the wings, but yet determinable to high accuracy by sub-sampled spatially-varying modeling of first-guess Tiny Tim grids followed by empirical improvements. I develop and illustrate these conclusions using both real HST/WFPC2 data of the Milky Way bulge globular cluster NGC 6293 in the F555W and F814W bands, and realistic simulations of a globular cluster observed under similar circumstances.
Back to Volume