To:sot_shift from: Dan Schwartz date: 03 Apr 02, 12:00noon EST Subject: SOT shift report 2002-04-03 L986 -------- See http://asc.harvard.edu/acis/SOT_reports/sot-shift.html, or /proj/ascwww/AXAF/extra/science/htdocs/acis/SOT_reports/Apr_03_2002_L986.txt. Shift L986. Start at 093:13:00 GMT = 08:00am 03 Apr EST End 12:00 noon 03 Apr SOT Lead DAS (Times will be given in GMT on day 093.) PLAN ---- Load has been halted. Upload APR0302C and resume science observing with the VELA pulsar wind nebula, obsid 2819. Next Comms: 093:1345 to 1445 Extended to 16:00, to resume observations 094:0030 to 0130 094:0900 to 1000 094:1730 to 1830 095:0230 to 0330 095:1100 to 1300 095:2100 to 2200 096:0500 to 0600 096:1500 to 1600 096:2230 to 2330 097:0720 to 0920 097:1740 to 1840 Orbital events: 2002:093:18:08:33.494 367 ORBIT APOGEE 2002:095:01:53:02.677 367 ORBIT PERIGEE 2002:096:09:36:13.313 368 ORBIT APOGEE 2002:097:17:20:21.888 368 ORBIT PERIGEE 2002:099:01:03:45.984 369 ORBIT APOGEE 2002:100:08:47:09.593 369 ORBIT PERIGEE EVENTS ------ Status at LOS, 093:05:58, was as follows: PCAD MODE = NPNT CONTROL LAW FLAG = NPNT Stars: = 5 FIDS = 0 RA = 265.202 deg Dec = -53.687 deg ROLL = 79.504 deg Format = 2 OBSID = 61246 SIM FA = -535 SIM TSC = -99616 (HRC-S) HETG = OUT (79.46 deg) LETG = OUT (77.96 deg) HRC-S HV is ON EPHIN Geom = LARG E1300 = 0.0 LT 10.0 (RADMON P4GM = 0.0 LT 300. Triggers) P41GM = 0.0 LT 8.47 A-leak = 1.0200 mu-a B-leak = 0.5520 mu-a Ascending through 121558 km. ACIS focal plane temperature -119.9. Status at AOS, 13:47:54, was as follows: PCAD MODE = NPNT CONTROL LAW FLAG = NPNT Stars: = 5 FIDS = 0 RA = 265.201 deg Dec = -53.685 deg ROLL = 79.504 deg Format = 2 OBSID = 61246 SIM FA = -535 SIM TSC = -99616 (HRC-S) HETG = OUT (79.46 deg) LETG = OUT (77.96 deg) HRC-S HV is ON EPHIN Geom = LARG E1300 = 0.0 LT 10.0 (RADMON P4GM = 0.1 LT 300. Triggers) P41GM = 0.0 LT 8.47 A-leak = 1.0200 mu-a B-leak = 0.5680 mu-a Ascending through 134160 km. ACIS focal plane temperature -119.9. 093:14:50 Run CAP 675 to re-enable SCS 107. 093:15:30 Start executing APR0302C. Start maneuver to target. Status at LOS, 093:15:59, was as follows: PCAD MODE = NPNT CONTROL LAW FLAG = NPNT Stars: = 0 Maneuver has just completed, FIDS = 0 no stars acquired yet RA = 128.816 deg Dec = -45.185 deg ROLL = 285.965 deg Format = 2 OBSID = 2819 VELA PWN SIM FA = -467 SIM TSC = 75623 (ACIS-S) HETG = OUT (79.46 deg) LETG = OUT (77.96 deg) HRC-S HV is ON EPHIN Geom = LARG E1300 = 0.0 LT 10.0 (RADMON P4GM = 0.0 LT 300. Triggers) P41GM = 0.0 LT 8.47 A-leak = 1.0200 mu-a B-leak = 0.5680 mu-a Ascending through 135527 km. ACIS focal plane temperature -119.7. 093:14:50 Run CAP 675 to re-enable SCS 107. 093:15:30 Start executing APR0302C. Start maneuver to target. NOTES/ISSUES/PROBLEMS SCS 107 tripped at 092:1750. From Rob's email report: " Engineering review of the SSR playback data from the time of the SCS107 trip, at 092:1750 showed that EPHIN radiation rates were well below RADMON thresholds, and that EPHIN and EIO voltages and currents were normal. The EPHIN temperature was about 81F. The EPHIN and EIO counter telemetry from the CTU showed no anomalies, and the counter values at the time of the EPHIN failure flag matched the values held in OBC memory. This is the same signature (or non-signature) of an EPHIN counter glitch that happened on 2001/336. During the 092/0500-0600 pass, CAPs 750C, 771, 750B and 508 were successfully run. These do the following: - dump the OBC memory containing the EPHIN and EIO frame counters - dump the 16-bit process flag word in the executive - set the RADMON Initialization bit in the process flag word to restart RADMON and clear the EPHIN failure count - re-verify the process flag word and verify the frame counters - re-enable RADMON. At the end of comm, Chandra's status was; the OBC failure was cleared, SI's safed, RADMON enabled and SCS107 disabled." From the 9am status meeting: Spacecraft transmitter had to be commanded on at the 092:19:15 pass, due to the SCS 107 shutdown of the APR0102B command program. CAP 750G was run to dump the EIO counter values, and this led to the diagnosis and course of action described in Rob's note above. Load APR0302C has been approved, and is planned to be uplinked during the current comm, to resume science observations at 093:16:03 In view of the above activity, review of the APR0802B load is postponed until tomorrow. The safe mode recovery simulation could not take place yesterday, due to a problem with the ASVT computer system. As of this time it is not resolved, and may be either hardware or software. The sim will be rescheduled after the problem is resolved. Star Selection and aspect working group telecon is cancelled for today. There will be a 2:30 telecon on planning the ASVT models upgrade. Call 405 244 5060, pin 1165#. CAP 675 was run to re-enable SCS 107, the APR0302C loads were uplinked, and activated as planned at 093:15:30. The EPHIN and EIO hardware failure flags were toggling properly. A working hypothesis continues to be that a very slight, and random, timing error caused the OBC to miss the flag, causing the false hardware failure indications. Thanks to many who worked through the night to enable a rapid resumption of the science observing program. A net 70.9 ksec of science observing time was lost. Quick look data: OBSID Target Time Comment ----- ------ -------------- ------- 1664 V 1525+0958 091:11:31 ACIS-I NONE Looks good ------------------------------------------------------- Dan Schwartz, MS #3 das@head-cfa.harvard.edu phone: (617)495-7232 FAX: (617)495-7356 cell phone: (617)512-5627 pager: 877-693-7198 PIN 693-7198 or e-mail 6937198@archwireless.net -------------------------------------------------------