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Hubble Space Telescope
GHRS Instrument Science Report 068

GHRS Instrument Science Report 068

"FOS-Assisted GHRS Target Acquisition"  11/94

Claus Leitherer, Anuradha Koratkar, Olivia Lupie and Steve Hulbert

Abstract excerpted from the report:

We describe the results of a test in which blind offsets between the 4.3" 
aperture on the blue side of the FOS and the GHRS Large Science Aperture 
were performed. The goal of this test was to demonstrate that the FOS can be 
used to acquire faint targets for subsequent spectroscopic observations with  
the GHRS. The test was successful. Three different stars were observed.  
They were found to be offset from the PDB position of the LSA by 0.2"  0.1" 
and 0.0"  0.1" in V2 and V3, respectively. It is recommended to offer this 
capability to observers using the GHRS who would otherwise not be able to 
acquire their target. The possibility also exists to offset targets from the 
GHRS to the FOS apertures. However, the magnitude of the uncertainty in 
the position of the GHRS LSA aperture (0.1") is large enough that a direct 
acquisition of a target into the FOS apertures would not be efficient.