Poster to presented at 193rd AAS meeting in Austin, Texas on 5-9 January 1999:
An Investigation of the Performance of CCD Stellar Photometry with a 1.5-micron Diffraction-Limited 8-m Next Generation Space Telescope
Kenneth J. Mighell (KPNO/NOAO)
I present the results of an investigation of the performance of CCD stellar photometry with a 1.5-micron diffraction-limited 8-m Next Generation Space Telescope. These simulations used artificial Point Spread Functions for three different 8-m NGST design concepts which were kindly provided by John Krist. Assuming that the 8-m NGST primary mirror has 1/13 wave RMS errors at 1.5 micron, I demonstrate that 90% of the light from a star falls within an aperture radius of 0.1 arcsec --- the size of one WF pixel of the Hubble Space Telescope WFPC2 instrument. The three NGST design concepts have nearly identical V-band encircled-energy functions; the degradation caused by the differences between the different design concepts is quite negligible when state-of-the-art digital-PSF photometric reduction software is used to analyze uncrowded stellar fields. All the V-band PSFs used in these simulations were sampled at 0.0064 arcsec/pixel which is the critical V-band sampling rate of a perfect 0.5-micron diffraction-limited 8-m NGST. Better photometric performance for all three NGST design concepts could be obtained by using larger CCD pixels: a pixel size of ~0.013 (~2 x 0.0064) arcsec/pixel should provide an optimal pixel sampling when the 8-m primary mirror is diffraction-limited at 1.5 micron.
Kenneth Mighell Associate Scientist Kitt Peak National Observatory National Optical Astronomy Observatories EMAIL: firstname.lastname@example.org MAIL: P.O. Box 26732, Tucson, AZ 85726-6732 FEDEX: 950 N. Cherry Ave., Tucson, AZ 85719 PHONE: (520) 318-8391 FAX: (520) 318-8360 URL: http://www.noao.edu/noao/staff/mighell/