Next: Simulated Test Data
Star Detection, Astrometry, and Photometry in Restored PC Images
Don Lindler
Advanced Computer Concepts, Inc., Code 681, Goddard Space Flight Center
Greenbelt, MD 20771
Sara Heap
NASA/Goddard Space Flight Center, Code 681, Greenbelt, MD 20771
Jarita Holbrook
University Space Research Association, Code 681, Greenbelt, MD 20771
Eliot Malumuth
Computer Sciences Corporation, Code 681, Goddard Space Flight Center,
Greenbelt, MD 20771
Dara Norman and Patricia C. Vener-Saavedra
Advanced Computer Concepts, Inc., Code 681, Goddard Space Flight Center
Greenbelt, MD 20771
Abstract:
We have evaluated various image restoration techniques (both linear and
non-linear) applied to a simulated crowded star field observed with the HST
Planetary Camera (PC). Evaluation criteria included star detection,
astrometry, and photometry. Numerous restoration artifacts made star
detection difficult for the linear restorations. The non-linear methods
give much better star detection and slightly better astrometry results.
Aperture photometry measurements in images restored with the non-linear
restoration methods
show significant non-linearities. The flux of fainter stars are
systematically underestimated. This problem is not seen in the images
restored with the linear methods. However, we see significantly increased RMS
scatter in the photometry results for images restored with a linear method. We
found that a hybrid approach which combines the result of a non-linear method
with a linear method will give linear photometry results with lower
RMS scatter.