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Reduction of Simulated Data

The simulated frames are then fed into the subsection of the current (protocamera) pipeline involved in point source extraction. The two pieces of the pipeline having the greatest impact on photometry are the offset determination and the profile fit photometry code. For the initial simulations presented here, the cumulative effect of the current pipeline code is being tested. Specifically, we are investigating the effect of the input ``observational'' parameters on simulated data as indicated by errors in the photometry and the positions returned by the photometry code.

The comparison between input truth and output measurements will show how sensitive the current code is to certain instrumental/observational effects, and aid in future development. Again, the software being used to reduced the simulated frames was taken from the current pipeline. Some of the following results may be most comparable to the recent (June '94) protocamera data. More importantly, the simulator will allow us to test proposed changes to the pipeline.

Photometry of simulated stars are produced in a way almost exactly like that in the protocamera pipeline, except for the use of a point spread fuction (PSF). Rather than use a single PSF for all scans, a PSF was determined for each scan. The extracted PSFs are uniform enough among scans of the same type of simulation that the photometry does not seem to be drastically affected. Thus the PSF fitting in the simulations should be at least as consistent as in the protocamera pipeline.

Gaylin Laughlin
Wed Feb 15 09:43:14 PST 1995