Sunday 12 September 1999 12.00pm EST
|During the last 24 hours the on-board load (P13) began operation and a number of ACIS tests were conducted in parallel. The ACIS test to lower the focal plane temperature to -110 C resulted in a significant improvement of the front-side illuminated chip energy resolution. A further test at -120 C is currently in progress. The SIM was positioned with ACIS at the focal plane for the current radiation passage in order to test the theory that resolution degradation is related to SIM position during radiation passage.
An anomaly related to the LETG insertion commanded by the load was detected during the communication pass at 7am 9/12. The grating insertion near the start of the load did not occur and the flight software aborted the insertion sequence. The load continued to run as expected. Analysis of the dump data indicated that the Mechanism Control Electronics (MCE) was not turned off at the completion of the previous retraction and is thought to be the cause. The behavior of conditions. Current plan is to perform the LETG insertion via real-time commanding and continue analysis with focus on the software timing.
Observations of Capella are planned with HRC-S and LETG in conjunction with the Hubble Space Telescope, EUVE, BeppoSAX and the Very Large Array (VLA) over the next 24 hours.
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