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A.B. Schultz, D. Fraquelli (CSC/STScI), D. Calzetti, S. Arribas, L. Bergeron, T. B\ddot{o}ker, M. Dickinson, S. Holfeltz, B. Monroe, K. Noll, M. Sosey (STScI)
We present an overview of NICMOS coronagraphy during the time interval February 6, 1998 through December 18, 1998. The NICMOS flight software (FSW) was enchance to locate the position of the coronagraphic hole as well as the target for on-board acquisitions. Acquisition strategies for bright targets (H \leq 3.6) were developed and confirmed with 30 successful acquisitions performed. During HST Observing Cycles 7 and 7-N, over 3,000 coronagraphic observations were obtained.
A review of the coronagraphic data suggests that there are two observing strategy domains for coronagraphy, one for companions or targets within the wings of the PSF (\leq ~15 pixels, ~1.125\arcsec) and another for those at larger separations (\geq ~25 pixels, ~1.9\arcsec) from the primary star. The recommended observing strategy for close in objects is to obtain observations with the same filter back-to-back in the same orbit with a roll of the telescope between observations, while for the latter, observations of the same target in consecutive orbits with a roll between orbits should be sufficient for PSF subtraction. We expect the performance of this observing strategy to remain unaltered after the NICMOS is revived with the NICMOS Cooling System (NCS).
Support for this work has been provided by the Space Telescope Science Institute which is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS 5-26555.
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