SSOC TOHBAN REPORT FOR WEEK 24 (Jun 14 - Jun 21) OF 1993 21-June-1993 SSOC: Sato, LaBonte KSC: Shiomi, Kozuka 1) SOLAR ACTIVITY Solar activity was very low. The largest flare was C3.5. The GOES background was in the A level. Welcome to the solar minimum. 2) SXT TABLE UPLOADS Month Day PASS ID TABLE NAME Jun 15 930615-0308 930615 T1 P1 ARS1 PF2 FST2 -0411 T2 P3 FAST BP TEST -0514 T3 P4 ARS1 + LONG Jun 16 930616-0205 930616 T1 P2 ARS1 + DARK Jun 17 930617-0205 930617 T1 P2 CORONA + ARS1 -0412 T2 P4 ARS1 + LONG Jun 19 930618-1548 930619 T1 P2 ARS2 PFI FST2 -0310 T2 P4 ARS2 + LONG 3) STT TIMER SET The STT timer was set on Jun 17 Pass1 930617-0102 and the STT track check is OK. 4) OG UPDATE Jun 15 Pass1 930615-0204 OG write for BCS calibration OG Numbers 88 - 95 BCS PHA/SCA check OG's 5) SPECIAL OPERATIONS Jun 15 Pass 4-5 CMPN OBS (07:24 - 07:39 UT) for BCS PHA/SCA check by OP Jun 17 Pass 2 ROG 73hex S/C East (18') Pass 2-3 CMPN OBS (03:07 - 03:10 UT) for SXT terminator image Pass 3 ROG 74hex S/C West (18') Pass 3-4 CMPN OBS (04:44 - 04:47 UT) for SXt terminator image Pass 4 ROG 72hex S/C Normal Point See attached report on SXT offset pointing operations. 6) ERRORS AND PROBLEMS a) SXT Bitmap error Jun 14 Pass 1 -> Recovered on Pass 1 Jun 15 Pass 1 -> Recovered on Pass 1 b) BCS error Jun 16 Pass 2 -> BCS recovery on Pass 3 See attached report on instrument errors and false flare flags. c) DSN data problems DOY 161 Passes at DSS-46 (Canberra) at 17:25,19:10, and 20:52 were all received corrupted. A retransmission from the JPL database was also corrupted. A retransmission from the Canberra station has been received and it will be checked for quality today (Monday Jun 21). The Strawman schedule for Week 27 arrived 1 day later than normal. This was probably caused by the Space Shuttle activity. The DSN report for Week 23 shows 97.6 percent data collection. They point out that the tracking time bias is usually zero when new orbital elements arrive but increases through the week, and the increase is increasing with time. The bias is only about 20 seconds at worse; in future, a better scheme for elements may be needed if the bias gets large enough to affect data dumps. d) COMPUTER PROBLEMS At KSC the A400 was down for part of two passes on Jun 17. The S3500 was operational and no data was lost. The SIRIUS reformatter stopped for a period on Jun 15 before it processed the Pass 1 data. This caused some trouble in preparing the SXT table for Pass 3. There were minor troubles with the KSC FAX and/or the Macintosh FAX on Jun 15 which also slowed the communication of SXT tables to KSC. The SSOC was able to get the information through. 7) HIKITSUGI a) The Space Shuttle is schedule to launch today. One DSN Pass for each of DOY 172, 175 and and 177 have been cancelled. Another was switched to a different antenna at the same site (this does not affect us). More realtime changes may happen. b) The next STT timer set is scheduled on or before Thursday Jun 24. c) Tohbans for Week 25: SSOC: Morimoto, Sterling; KSC: Kozuka, Shimizu Sterling will be updating the English version of the tohban manual. Input is needed. d) Scheduled SXT operations are Dark calibrations on Wednesday Jun 23, Offset pointing on Thursday, subject to the decision of the SXT Chief Observer. ************************************************************************** June 17, 1993 To: Yohkoh people Subject: Offpoint operations today From: Barry LaBonte Sato-san and I followed the directions provided by Hudson at the June 14 operations meeting and had a successful off-point operation. 1) All three pointings (East, West, Normal) worked fine. We monitored the final pointing, returning to Normal, in realtime. 2) The Campaign Mode images at the begining of the SXT table worked. We recorded stray light images at the Day/Night terminator of both Pass 2 (East) and Pass 3 (West). The exact sequence in both orbits was: Image Pass 2 Pass 3 1 X-ray + stray light X-ray + stray light 2 stray light stray light 3 dark dark (partial) 4 dark no image - Night 5 no image (Night) Hudson's timing was based on issuing the SXT CNTL AUT at -1:30 minutes with respect to the terminator time. The results of today's operation show that the time should be -2:00 minutes. The terminator times were those located by the IDL routine PR_FEM. 3) The 5 images were also taken during the Pass 3 pointing change. They show that the complete motion from East 18 arc minutes to West 18 arc minutes takes 2 minutes 10 seconds of time. 4) A simple subtraction of the decompressed images from the Campaigns shows structure out to 70 pxl (700 arcsec = 0.7 solar radii) above the east limb and 30 pxl above the west limb. The terminator exposures are 1.8 sec; the longest offpoint exposures are 15 sec in the same filter. The Sun was very quiet this day. 5) The Campaign Mode images are designed to measure the stray light. They are not needed once a complete set of stray light images appropriate to each filter are obtained. This must be coordinated with the SXT Table Manager. 6) A decision about putting the offpoint commands in the OP still needs to be considered. ************************************************************************** June 16, 1993 To: Yohkoh people From: Barry LaBonte Subject: Radiation Belt / Flare flags Hugh Hudson pointed out a large number of false flare flags occurred on 10-May-93 and asked the SSOC tohbans to look at the time plots to determine if the frequency of false events was increasing. Sato-san and I looked at the plots and found no increase. The period around 10-May-93 was anomalous. The time plots for the interval 05-May-93 00:00 UT to 11-June-93 23:59 UT were searched. There were 35 valid flare flags during this time. There were 22 anomalous flare flags; 12 occured in a 3 day interval in May. The KSC operations reports for the same interval were searched for instrument errors. The following table lists the anomalous flare flags and the instrument errors. False flare flags Instrument errors Date Time (U.T.) Date Time (U.T.) _______________________________________________________________________ 05-May 22:30 ? 08-May 10:35 08-May 20:50 - 22:26 " 11:25 " 12:15 09-May 09:20 (Sunday) " 10:50 " 12:35 " 13:25 10-May 09:35 10-May < 17:59 " 10:25 " 11:15 " 12:10 " 12:50 12-May Recovery to clear bad bit in SXT dark exposure timer 13-May 11:20 19-May 20:10 02-Jun 23:50 02-Jun 07:45 - 09:15 03-Jun 15:50 " 22:35 04-Jun 00:15 09-Jun 18:55 09-Jun < 04:51 " 22:10 11-Jun 02:35 ? _______________________________________ Conclusions: 1) There is a correlation between the instrument errors and the false flare flag. 2) Frequent false flare flags warn us to watch the instrument operation closely to detect errors that require recovery. 2) We might ask NOAA for access to GOES particle fluxes or geomagnetic activity indices to monitor the condition of the Earth's environment, as it affects the Yohkoh spacecraft and instrumments..