FOS Instrument Science Report # 118

"SMOV Report III: FOS Baseline Sensitivity"
by Charles (Tony) Keyes, Anne Kinney, Anuradha Koratkar, and Cynthia Taylor

Abstract excerpted from the report:
	Following Servicing Mission (SM) but before COSTAR delployment,
	spectrophotometric standard BD+28 4211 was observed with the 4.3
	aperture and several representative detector/dispenser combinations.
	The observations were compared with Cycle 3 measures obtained with 
	identical target acquisition and observational setups.  Measured
	FOS/BLUE and FOS/RED count rates were higher in the post-SM observations
	by approximately 7% and 6% respectively.  The increase in post-SM 
	instrumental sensitivity is consistent with predictions based upon
	HST secondary mirror re-positioning in the post-SM time period.  FOS
	instrumental sensitivity is unaffected by any SM-related activities.





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