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Session 70 - Searching for Other Planetary Systems.
Display session, Wednesday, January 17
North Banquet Hall, Convention Center

[70.21] First Results from HST/FOS Coronagraphic Imaging of Nearby Stars

H. M. Hart, A. B. Schultz, F. C. Hamilton, M. Kochte (CSC), F. C. Bruhweiler (Catholic U), G. F. Benedict (U.Texas), J. Caldwell, C. Cunningham (York University, Canada), O. G. Franz (Lowell Obs), C. D. Keyes (STScI), J. Brandt (U.Colo)

The Faint Object Spectrograph Red detector onboard the HST is now being used for the first time in ACQIMAGE mode with the large barred aperture to search for suspected companions to six cool stars in the solar neighborhood (HST proposal 6059). The FOS is ideal for detecting faint companions because of its large dynamic range, sensitivity, sub-arcsecond resolution, and low detector noise. The limiting magnitude of the FOS ACQIMAGE mode is mv= 22.

An ACQIMAGE is created when the FOS camera mirror images the aperture onto the photocathode. An on-orbit stellar image is rectangular because of the shape of the mapping diodes (0.31"x1.29"). Deconvolution is used to produce a final image scale of 0.08"/pixel. Preliminary modeling indicates a companion can be detected as close as 0.2" for a system of nearly equally bright stars, and as close as 0.8" if the magnitude difference between the primary star and its companion is ten magnitudes.

Two stars with known companions are included in the program in order to verify the new target location and imaging techniques. The other four stars have suspected companions. This paper is a report on the feasibility of this unique imaging capability, with preliminary results for Cycle 5 targets GL293 (successfully observed in September 1995) and GL1245AC (scheduled to be observed in December 1995).

Program listing for Wednesday