Kenneth Mighell (National Optical Astronomy Observatory)
Keywords: Astronomy
Abstract:
Current infrared detector technology can produce imagers with non-uniform intrapixel response functions. Cameras based on such detectors can have large systematic errors in the measurement of the total stellar flux. This problem can be mitigated by oversampling the stellar image, but many near infrared cameras are undersampled in order to achieve a large field of view. The combination of undersampling stellar images with non-uniform detectors is currently diminishing the science return of some infrared imagers onboard the Hubble and Spitzer Space Telescopes. Large intrapixel quantum efficiency variations can also cause significant systematic position measurement errors. Although the recorded flux and position of point sources is corrupted by using detectors with non-uniform intrapixel response functions, it is still possible to achieve excellent stellar photometry and astrometry ¬ if the image formation process inside the detector is accurately modeled. A practical demonstration of how the precision and accuracy of near infrared stellar photometry and astrometry can be significantly improved is provided by a detailed analysis of stellar observations obtained with Spitzers Infrared Array Camera (IRAC) instrument.
Date of Conference: September 10-14, 2006
Track: Astronomy