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.

Preliminary report (9 October 1998: 1.1 Mbytes, PostScript format)
Kenneth Mighell
Associate Scientist  
Kitt Peak National Observatory
National Optical Astronomy Observatories

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