Sunday, June 28, 2009
During the evening we installed the FORCAST electronics and computer on the aircraft and spent about 3 hours testing the interface that allows FORCAST to control the SOFIA telescope and chopping secondary mirror. This mirror system allows us to repeatedly "chop" (switch) between blank sky and our object of interest during astronomical observations so that we can subtract the considerable infrared background from the sky, telescope, and instrument. We need FORCAST to initiate chopping patterns so that it can synchronize the image exposures with the movements of the telescope mirror. The test was successful; we sent a signal to the telescope control system and verified that the mirror was responding properly. But we also measured a lot of noise on the return signal, which we suspected might degrade our data. We determined that the noise was coming from the aircraft and not our electronics, but the telescope operators could not find the noise source in their system. Hmmm...strange. We called it a night, but still had no explanation for that electronic noise.
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