Tuesday 21 September 1999 9.00am EST
|During the last 24 hours a series of GTO observations with both HRC and ACIS were completed, including the targets Abell 426 and M82. The spacecraft systems were nominal during this period.
Analysis of ACIS data from the last 2 radiation passages indicates no further degradation in the front-side chip energy resolution. The back side-chip data continues to show no change since launch. The initial results from the diagnostic tests run over the weekend show an increasing trend of energy resolution loss as the focal plane operated at higher temperatures (-110 to -60 deg C range), then indication of turn over at -60 deg C. These results are expected to help identify the type of effect causing the degradation in energy resolution.
The next load was prepared yesterday and reviewed overnight, and will perform a set of ACIS GTO observations including 30-Doradus and Abell 3667. Additional calibration measurements will also be made with Capella. ACIS internal calibration measurements will be taken prior to the next radiation belt entry on Tuesday evening, and prior to the next eclipse on Wedensday at 5am.
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