SOT Shift Report Shift M84 Duration: 15 Oct 1999 12:30 EDT - 15 Oct 1999 17:00 EDT 15 Oct 1999 16:30 GMT - 15 Oct 1999 21:00 GMT SOT Lead: Robert Cameron Spacecraft/Aspect: FOT/Science Liason: HRC: ACIS: Yousaf Butt,Royce Buehler ======================================== Plan ---- Schedule an extra DSN DSS 61 comm to perform CAP 477. CAP 477: Change ACIS PB during ObsId 581, to adjust FEP parameters. FEP power down for radiation zone passage, by realtime command. Events ------ GMT Event 288:16:30 AOS on DSS 61 288:17:20 Upload new ACIS PB 288:17:30 ACIS stop science 288:17:39 change to obsid 1431 288:18:14 LOS Notes/Issues/Problems --------------------- The power down of the FEPs for tonight's radiation zone entry will be done by realtime command tonight. For daily loads P22 and later, FEP powerdown will be included in the daily load. Andy Northrup has built CAP 479, to be used in an emergency to safe ACIS and HRC prior to radiation. This is a stopgap measure until a more complete SI safing script is ready. From Yousaf Butt: Due to the problem with fep0 on ACIS, the current & ongoing observation, OBSID 581 (AXAF Southern Deep Field), had it's PB changed from WT001B4014 to WT00212014 (SI mode: TE_00212). It uses FEP's 1-5 instead of 0-4. However, examination of the downlink from the last pass (10 am local today) indicated anomalous (saturated) readings from FEP5. Royce then diagnosed the problem to an incorrect mapping of the bias arguments in the new PB. ie. fep mapping changed, but bias arguments were the same as before. This, presumably, did not show up in the ACIS engineering unit test of the PB since we did not have real events there. I'm attempting to get additional real time contact to intervene and stop & re-start the run with a modified (or previously used) PB. (At this point we have possibly corrupted -or "dropped" -data for the last ~18 hrs of OBSID 581, certainly for fep5=CCD6=S2.) From Jan Vrtilek: 1431 970381 1999Oct15 16:00 J. Vrtilek P21: clone of 581 for realtime ACIS setup change From Mike Wise: As you probably know, there were some problems recently with ACIS related to some misbehavior with the front end processor on the S3 chip. I won't go into the details of the problem since I barely understand them myself and someone like Peter could give you a better explanation anyway. The net result of this problem, however, was that the telemetry stream was saturated with many erroneous events resulting in many dropped frames. Dropping frames of course effectively reduces the exposure time of the observation. This trouble with the S3 chip affected two of our HETG GTO observations. The relevant observations are: HETG/ACIS-S NGC1275 OBSID 333 HETG/ACIS-S PKS0745-191 OBSID 1383 Due to this telemetry saturation, both of these observations had effective exposure times which were substantially smaller than approved. In the case of NGC1275, we obtained an exposure roughly 40% of the requested exposure. For PKS0745-191, the loss was even more severe, with an effective exposure of roughly 10% of the scheduled 50 ksec. Needless to say, these differences are significant and have a big impact on the science we hope to do with these objects. Consequently, we'd like to request that these objects be re-observed. If possible, we'd like to re-observed these objects quickly in order to obtain the same roll angles. If there is a more formal procedure for such eventualities, just let me know and we'll start jumping through those hoops. From Peter Ford: FEP_0 has again generated thousands of bias parity errors during two recent science runs: OBSID 510 (PKS_0745-191) and 965 (A2256). We're currently running OBSID 581 (AXAF Southern Deep Field) which doesn't use FEP_0. At first glance, the failure appears to be identical to that seen prior to power-cycling the board, which tends to rule out a random SEU as a likely explanation. We enter radiation belts after this science run, so we'll be powering the FEPs down and we have some time to think this through. The ACIS SI team will be meeting at 4:00 pm on the 6th floor of NE-80. Spacecraft Snapshot ------------------- UTC 1999:288:16:55:01 (Fri Oct 15) OBT 1999:288:16:54:39 CTUVCDU 6207231 FMT2_EPS OBC s/w NRML OBC Errs 0 OBT 56393679.60 ONLVCDU 6207224 OBSID 581 EPState SUN SIM TTpos 92903 HETG Angle 81.0 PCADMODE NPNT RA 53.115 Bus V 30.71 SIM FApos -535 LETG Angle 81.3 PCONTROL NPNT Dec -27.836 Bus I 28.49 AOFSTAR GUID Roll 47.071 ACA Object FFFSSSSS Dither ENAB HRC-I HV OFF ACA ImFunc TTTTTTTT Dith Yang -6.18 Yaw Rate 0.02 HRC-S HV OFF ACA CCD Temp -10.4 Dith Zang 6.33 Pitch Rate 0.25 OBSMode NEXT ACA Int Time 1.698 Roll Rate 0.01 Door OP UNAC AOACSTAT OK FSS SunAlfa SUN Door CL UNAC FSS Alfa -1.43 Batt 1 SOC 100.00% Avg HRMA Temp 70.61 FSS Beta -41.96 Batt 2 SOC 100.00% Avg OBA Temp 50.58 SA Resolv 131.65 Batt 3 SOC 100.00% ACIS Stat7-0 64 OBA Tavg Fault NFLT SA Sun Pres ILLM Cold Rad -120.7 OBA Trng Fault NFLT Warm Rad -82.0 HRMA power 61.30 OBA power 8.10 EPHIN Geom LARG INT cnt 98 Roll Mom. 4.065 P41GM cnt 0 Pitch Mom. -10.733 A-Leak 0.1840 Yaw Mom. -0.704 B-Leak 0.0280