GHRS Instrument Science Report 045 Controlling Background Noise for GHRS Observations: CENSOR 11/92 Ronald L. Gilliland and Lisa E. Walter Abstract excerpted from the report: The GHRS has a flight software driven capability of lowering background noise levels by dropping (and then repeating) any individual step-times that showed an anti-coincidence event. This GHRS capability may be invoked by setting the optional parameter of CENSOR to YES (default is NO). Since the repetition of some step-times will result in a longer total integration period it is necessary to provide an alignment time pad for observations using CENSOR. Through analysis of existing data we show that a time pad of 2% should be adopted for CENSOR observations. Also supplied is a discussion of how CENSOR works and what target count rates will have an increased signal to noise as a result of invoking CENSOR. For best cases the expected gain in S/N through use of CENSOR is in the 10-20% range.
