To:sot_shift from: Dan Schwartz date: 03 Dec 01, 12:00noon EST Subject: SOT shift report 2001-12-03 L865 -------- See http://asc.harvard.edu/acis/SOT_reports/sot-shift.html, or /proj/ascwww/AXAF/extra/science/htdocs/acis/SOT_reports/Dec_03_2001_L865.txt. Shift L865. Start at 337:13:00 GMT = 08:00am 03 Dec EST End 12:00 noon 03 Dec SOT Lead DAS (Times will be given in GMT on day 337.) PLAN ---- Loads are stopped due to SCS 107 running at about 336:02:15 GMT (9:15 pm on Saturday night). Next Comms: 337:1440 to 1640 337:2300 to 0100 338:0800 to 0900 338:1530 to 1630 339:0045 to 0245 339:1130 to 1330 339:2015 to 2215 340:0245 to 0345 340:1300 to 1400 Orbital events: 2001:338:10:22:15.636 321 EPERIGEE ORBIT PERIGEE 2001:339:18:05:54.482 322 EAPOGEE ORBIT APOGEE 2001:341:01:51:06.084 322 EPERIGEE ORBIT PERIGEE 2001:342:09:34:21.745 323 EAPOGEE ORBIT APOGEE 2001:343:17:18:29.578 323 EPERIGEE ORBIT PERIGEE EVENTS ------ Status at LOS, 337:06:59, was as follows: PCAD MODE = NPNT CONTROL LAW FLAG = NPNT Stars: = 5 FIDS = 0 RA = 254.426 deg (position of Dec = 35.328 deg 0bsid ROLL = 353.285 deg 2704) Format = 2 OBSID = 61396 (not updated from CTI run) SIM FA = -535 SIM TSC = -99616 (HRC-S) HETG = OUT (79.46 deg) LETG = IN ( 4.46 deg)-SHOULD BE OUT HRC-S HV is ON EPHIN Geom = LARG E1300 = 0.0 LT 10.0 (RADMON P4GM = 0.3 LT 300. is disabled) P41GM = 0.0 LT 8.47 A-leak = 1.0200 mu-a B-leak = 0.3520 mu-a 14:40 AOS. Status essentially unchanged. Descending through 123827 km. ACIS focal plane temperature -119.9. NOTES/ISSUES/PROBLEMS From the 9am status meeting: Due to an apparent anomaly in the OBC'S EPHIN hardware failure flag, our onboard radiation protection software inadvertently tripped at about 336:02:15 GMT (9:15 pm on Saturday night) as we emerged from perigee. EPHIN appears to be working normally and properly, and the EIO unit is properly incrementing counters and putting data into telemetry. However, we do not see the different path by which the EIO communicates to the OBC. CAPs 750B and 750C were run to dump available ephin and EIO parameters from the OBC memory, and it was seen that in the OBC the EPHIN counter was 2 (should be 0 or 1) and that is consistent with SCS 107 having been commanded. We expect that the OBC flag was set spuriously by some rare event or timing problem. We are proceeding to develop a software patch to reset the OBC counter to zero. Then we will enable RADMON, prior to reenabling SCS 107, and watch if the hardware failure flag trips again. We expect it not to trip, in which case we will enable SCS 107 and proceed with the DEC0401 replan loads. If the hardware failure flag does trip again, we will have CAPs available for further diagnostic dumps, but we will not resume the observing program. The ephin failure flag is a reasonable and proper test. However, if this test persistently fails for spurious reasons, SOT believes the mission can proceed even if undiagnosed, as long as EPHIN itself is believed to be functioning properly. Either a higher error count requirement, or removing the hardware failure as a trigger to SCS 107, are potentially viable. Either is just a K-constant change. Many thermal readouts continue to show yellow limits. This is believed primarily due to perihelion passage, and the recent pointing positions. TRW West is doing a study of surface degradation and predictions of temperatures. DEC1001 products are out for initial comments, but on hold until the current week is replanned. DEC0401A was reviewed at 10am, and revised DEC0401B products issued to allow a load break after the first maneuver. This first maneuver must be done to get to a safe attitude even if we are not able to resume the science observing program. GOT wants to plan the December database backup for later this week. Quick look data: OBSID Target Time Comment ----- ------ -------------- ------- 3263 MACSJ0047.3-0810 333:17:21 ACIS-I NONE Looks Okay. 3173 PKS2155-304 333:21:43 ACIS-I LETG Looks Okay. 3174 PKS2155-304 334:00:04 ACIS-I LETG Looks Okay. 3166 PKS2155-304 334:02:30 HRC-S LETG Looks Okay. 3168 PKS2155-304 334:11:18 ACIS-S LETG Looks Okay. 3167 PKS2155-304 334:20:15 ACIS-S HETG Looks Okay. 3176 PKS2155-304 335:05:12 ACIS-I LETG Looks Okay. 3177 PKS2155-304 335:07:34 ACIS-I LETG Looks Okay. ------------------------------------------------------- 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 -------------------------------------------------------