SOT Shift Report Shift L97 Duration: 28 Oct 1999 08:00 EDT - 28 Oct 1999 12:00 EDT 28 Oct 1999 12:00 GMT - 28 Oct 1999 16:00 GMT SOT Lead: Tom Aldcroft Spacecraft/Aspect: FOT/Science Liason: HRC: ACIS: Yousaf Butt ======================================== Plan ---- Continue with load P23p2c (or p2b?) Events ------ 16:00 AOS on DSS-54 Notes/Issues/Problems --------------------- From the 9am meeting: - Bruce Twambly gave an update on the LETG A-side potentiometer status. Before the last 4 retraction attempts, the readings were 9, 10, 15, and 21 degrees. There was also an increase in measured retracted angle, although the last time it went *down* by 4 degrees. The upshot is that it appears noisy and unreliable, whereas the B-side pot measurements are solid. The question now being discussed is whether to completely fail over to the B-side MCE (which will require a flight software patch), or patch one word of flight software to make the A-side electronics read the B-side pot. - Jeff Shirer showed some good plots on the one-shot attitude update issue. One was update size versus maneuver angle, which showed the expected increase with angle, and also that there was just one update which exceeded the OFLS limit (from the Characteristics). However, there were a number that were within ~20 arcsecs of the line, which is a bit close. Another plot was of the ratio of update size / maneuver angle versus time, and showed that there has NOT been any change with time. A third plot showed pitch and yaw error versus maneuver angle for yaw maneuvers. The pitch error was generally smaller than yaw, and yaw error showed a clear asymmetry favoring negative errors. This could indicate a slightly low scale factor. Jeff will continue the investigation, but in the meantime the conclusion is that there is no immediate problem. Snapshots ------------- *** CURRENT UTC 1999:301:16:37:01 (Thu Oct 28) OBT 1999:301:16:36:40 CTUVCDU 10586239 FMT1_SSR OBC s/w NRML OBC Errs 0 OBT 57515800.49 ONLVCDU 10586232 OBSID 1416 EPState SUN SIM TTpos -99616 HETG Angle 81.0 PCADMODE NPNT RA 279.199 Bus V 30.55 SIM FApos -1119 LETG Angle 81.7 PCONTROL NPNT Dec 38.788 Bus I 30.01 AOFSTAR GUID Roll 295.061 ACA Object FFFSSSSS Dither ENAB HRC-I HV OFF ACA ImFunc TTTTTTTT Dith Yang 3.06 Yaw Rate -0.23 HRC-S HV ON ACA CCD Temp -10.4 Dith Zang 10.44 Pitch Rate -0.15 OBSMode OBSV ACA Int Time 1.698 Roll Rate 0.02 Door OP ACT AOACSTAT OK FSS SunAlfa SUN Door CL UNAC FSS Alfa -0.29 Batt 1 SOC 100.00% Avg HRMA Temp 70.61 FSS Beta 8.78 Batt 2 SOC 100.00% Avg OBA Temp 50.66 SA Resolv 81.11 Batt 3 SOC 100.00% ACIS Stat7-0 66 OBA Tavg Fault NFLT SA Sun Pres ILLM Cold Rad -120.7 OBA Trng Fault NFLT Warm Rad -82.0 HRMA power 40.40 OBA power 142.20 EPHIN Geom LARG INT cnt 122 Roll Mom. -5.365 P41GM cnt 1 Pitch Mom. 3.189 A-Leak 0.2200 Yaw Mom. 0.806 B-Leak 0.0360 *** PREVIOUS COMM AT 06:19 UTC 1999:301:14:13:00 (Thu Oct 28) OBT 1999:301:06:19:29 CTUVCDU 10441727 FMT1_NORM OBC s/w NRML OBC Errs 0 OBT 57478769.35 ONLVCDU 10441720 OBSID 1411 EPState SUN SIM TTpos -50505 HETG Angle 81.0 PCADMODE NPNT RA 148.975 Bus V 30.55 SIM FApos -715 LETG Angle 81.7 PCONTROL NPNT Dec 69.651 Bus I 32.54 AOFSTAR GUID Roll 60.438 ACA Object FFFSSSSS Dither ENAB HRC-I HV ON ACA ImFunc TTTTTTTT Dith Yang -2.92 Yaw Rate 0.17 HRC-S HV OFF ACA CCD Temp -10.4 Dith Zang 5.55 Pitch Rate -0.38 OBSMode OBSV ACA Int Time 1.698 Roll Rate 0.02 Door OP ACT AOACSTAT OK FSS SunAlfa SUN Door CL UNAC FSS Alfa -0.26 Batt 1 SOC 100.00% Avg HRMA Temp 70.58 FSS Beta -3.60 Batt 2 SOC 100.00% Avg OBA Temp 50.66 SA Resolv 93.39 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 58.30 OBA power 128.90 EPHIN Geom LARG INT cnt 122 Roll Mom. -5.528 P41GM cnt 0 Pitch Mom. -1.165 A-Leak 0.1920 Yaw Mom. 1.510 B-Leak 0.0320