Preprint Logo P17 March
1998


To be published in:
Proceedings of the 1997 HST calibration Workshop

WFPC2 Photometry via subtraction of TinyTim PSFs

M. Remy1, J. Surdej1,*, S. Baggett2 and M. Wiggs2


1 Institut d'Astrophysique et de Géophysique - Université de Liège, Avenue de Cointe 5, 4000 Liège, Belgium
2 Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA

* Directeur de Recherches FNRS, Belgium


Abstract

     Based upon the subtraction of TinyTim PSFs from PC1 point-like objects, a method has been developed to determine the optimal values for the telescope jitter and the Z4 relative focus during calibration or science observations. Using these jitter and focus values, an optimal TinyTim PSF, computed over a resampled grid, is then iteratively fitted to the object, yielding an improvement in the PSF centering, more accurate photometric results and a better detection of underlying structures.

Files
Article: wfpc2-tt.ps.gz (74699 bytes): HTTP FTP (ftp://vela.astro.ulg.ac.be/preprints/)


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