To:sot_shift from: Dan Schwartz date: 19 Aug 99, 02:00pm EDT Subject: SOT shift report, Shift L28 -------- See http://asc.harvard.edu/acis/SOT_reports/sot-shift.html, or /proj/ascwww/AXAF/extra/science/htdocs/acis/SOT_reports/Aug_19_1999_L28.txt. Shift L28 Start at 231:10:00 GMT = 06:00am 19 Aug EDT End 02:00pm 19 Aug SOT Lead DAS Spac/Aspect RAC FOT/Sci liason HRC SSM,JHC,GM,MJ ACIS (Times will be given in GMT on day 230. In general times are rough, not precise.) PLAN Complete safe mode cleanups Turn on HRC HV, initiate internal cal in format 1, Review load for SCS segment #3, load segment #3 Run SAP 61044 to turn on ACIS video board clocking. EVENTS In Format 1, OBSID 62448 HRC antico shield on. Rates very high, (45000 vs 4100 per sec normal), at the 60,000 km turn-on point. Fall a factor of 10 in roughly 1500seconds. HRC-I HV on. Close HRC door. Rates higher than usual, see illumination on the corner nearest the optical axis -- due to electrons or stray light??? HRC sees cal source, but background is varying so exact rates are hard to determine. HRC-I remains on 11:00 resume PCAD safe mode cleanup activities 11:05 CAP to resume cooling of ACA focal plane. Was up to 14 deg C, will cool to -10 deg C Playback SSR, finish ~11:24. 12:00 LOS from Canberra 12:50 CAP to translate SIM to the nominal ACIS-S on-axis position. 13:30 Run CAP 315 to start an ACIS science run. 15:21 LOS from Diego NOTES/ISSUES/PROBLEMS The VCDU counter was reset when we recovered from Safe Mode, and initiated OBC-A control. This was approximately 231:00:12:07 (by calculation, may be a second in error). During SIM translation we see 170 arcsec motion in acceleration phase, 250 arcsec displacement in pitch during deceleration, then asymptotically recovers in about 200 seconds time. The ACIS science run was for the purpose of clearing the CCDs of charge that accumulates during a radiation belt passage. We continue in format 1 taking HRC cal source data, and continue with the OBSID = 62448. ACIS will trickle bias data for a very long time -- when we come back to FORMAT 2 (planned very roughly for 2200 GMT tonight) ACIS will dump the remainder of the bias, and then there will be a large time gap and then ACIS events will be telemetered. NOTE: Because we are in format 1, ACIS will NOT telemeter the Huffman tables. These will be the same tables used in previous runs, so those should be retrieved and applied to the present bias maps. OBSID 62448 will remain until the start of segment #3 of the SCS, which will change the OBSID to 214 for the CAS A first light picture. During the OBC-B to OBC-A recovery from safe mode, the HRMA thermal control was disabled from 23:54 to 01:09 last night. We expect the small perturbation to have settled prior to the CAS A observation tonight -- analysis in progress by FOT thermal. ------------------------------------------------------- Dan Schwartz, MS #3 das@head-cfa.harvard.edu phone: (617)495-7232 FAX: (617)495-7356 cell phone: (617)512-5627 pager: 800-759-8352 PIN 1636502 or e-mail 1636502@skytel.com -------------------------------------------------------