SSOC Tohban's Report for Week 16 (12-APR-99 -- 18-APR-99) SSOC : S. Akiyama and B. LaBonte KSC : M. Hagino and K.Kobayashi 0. Meeting Attendance S.Akiyama, H.Hudson, J.Khan, B.LaBonte, K. Matsuzaki, H. Nakajima, M. Shimojo, T. Watanabe -------------------------------------------------------------- 1. Solar Activity Solar activity was low during Week 16, with only a few flares as large as C-class (see plot). -------------------------------------------------------------- 2. Standard Operations 2.1 SXT Table Uploads The following SXT tables were uploaded during week 16: ===================================================== JST Date Pass Table ID ===================================================== 12-APR-99 1 990411 P1 ARS2 LOOP 12-APR-99 2 990411 P2 ARS1 STD 13-APR-99 1 990412 P1 ARS2 VLA 13-APR-99 3 990412 P3 ARS1 STD 14-APR-99 1 990413 P1 ARS0 BAKEOUT 14-APR-99 4 990413 P4 ARS1 DIF 15-APR-99 1 990414 P1 ARS0 BAKEOUT 16-APR-99 3 990415 P3 ARS1 DAR 17-APR-99 2 990416 P2 ARS1 STD 17-Apr-99 3 990416 P3 ARS2 STARE 17-APR-99 4 990416 P4 ARS2 STARE ===================================================== 2.2 STT Timer setting STT timer was set during pass 2 on 13-APR-99 (JST). -------------------------------------------------------------- 3. Errors and Problems 3.1 BCS Errors: Invisible rror on Pass 1 17-Apr, cleared by Pass 5. 3.2 SXT Errors: None 3.3 NASA Tracking Stations: See Section 5.2. 3.4 Human errors: -- On Wednesday morning, 14-APR-99, a series of human errors and misunderstandings occurred which caused the loss of 1 orbit of data. The A400 operator from Fujitsu failed to show up for Pass 1. The KSC tohbans decided to go ahead with the operations, but were unaware that the A400 was needed for table comparison. Comparison failed, and they executed the SXT Yobi-A command sequence which puts SXT in CTL MANUAL mode. They performed the SXT TBL READ command at the beginning of Pass 2 as instructed by Hara-san, and the comparison was successful. -- The situation was more fragile than this simple error. The KSC contacts were in the early morning. The KSC tohbans were able to call Hara-san, but could only reach the SXT Chief Observer by Email. Both Nitta-san and Hudson-san called KSC just before Pass 2. The loss of data could have been larger. A bakeout of the CCD was planned for Pass 2, with the TEC OFF scheduled. Hara-san suggested the bakeout could go ahead, if the SXT CO agreed. Both SXT COs advised cancelling the bakeout, and that was done; a different SXT table was uplinked on Pass 4. Yohkoh only has 3 KSC contacts on many days because of ASCA conflicts. Besides the SXT table problems in Pass 1, there was also a mistake in the command plan. After OP WRITE, we sent an ACS MOD H, which is standard for night mode. This locks the satellite in ACS mode, so when the Day OG was sent in realtime, (ROG 37), the satellite stayed in ACS mode. In short, we forgot the "MOD CTL AT" and "SXT CHK DIS" after ROG 37. This oversight was missed by all 4 tohbans in checking the command sheets. The KSC tohbans realized what was wrong and entered the addtional commands, but this unrelated mistake added to their burden in dealing with the other problems. -------------------------------------------------------------- 4. Special Operations The OG for Normal Pointing was modified and uplinked on 13-APR-99 to adjust the position of the solar image on the SXT CCD. A second modification and uplink was made on 17-APR-99 to refine the pointing further. -------------------------------------------------------------- 5. NASA Station Scheduling 5.1 Contact pass cancels/adds The following DSN/NASA passes were added/deleted: =================================================================== DSN/NASA Schedule Week Schedule Changes =================================================================== Realtime 16 1 pass deleted by SSOC (Santiago/KSC) Final 17 1 pass deleted by SSOC (Santiago/KSC) Preliminary 18 0 passes deleted by SSOC Strawman 19 53 passes deleted by SSOC =================================================================== 5.2 Data Transmission from NASA Ground Stations -(From /home/flare1/yohkoh/dsn_corrupt/99_16)------------ 090 80 2118 not received requested 06 Apr no response requested 13 Apr Closed/ correct data 090 80 2301 corrupted tape requested 13 Apr Closed/ correct data 091 80 1951 corrupted tape requested 08 Apr Closed/ same data 091 80 2133 corrupted tape requested 08 Apr Closed/ same data 093 80 1657 corrupted tape requested 08 Apr Closed/ Correct data 093 80 2022 corrupted tape requested 08 Apr Closed/ Correct data 094 80 1712 corrupted tape requested 08 Apr Closed/ Same data 096 80 2109 corrupted tape requested 13 A Closed/ correct data 099 80 1322 not received requested 13 Apr Closed/ correct data 099 80 1504 not received requested 13 Apr Closed/ correct data 099 80 1646 not received requested 14 Apr Closed/ correct data 098 80 1449 Degraded data due to antenna losing autotrack and running off s/c 5.3 Statistics of Yohkoh downlinks At the Weekly Operations Meeting on 12-APR-99, the issue of Yohkoh data downlink was discussed. A request was made that the SSOC tohbans look at the statistics of contacts at present. A report is appended at the end of this regular SSOC tohban report. -------------------------------------------------------------- 6. KSC Pass Conflicts and Schedule 6.1 Weekly conflict meeting In week 17, 10 KSC contacts to ASCA, 0 to AKEBONO. 6.2 KSC - Santiago downlinks The Santiago station of the DSN lies on the same orbits as KSC. Santiago passes are valuable for times when Yohkoh loses contacts to spacecraft conflicts. The weekly conflict meeting for Week 17 occurs after the arrival of the DSN Final schedule for Week 17. Therefore, we must cancel or add Santiago contacts at Final. However, the orbital predictions for the spacecraft are accurate enough to allow the creation of the DSN Strawman Forecast for Week 19. Better planning of DSN Santiago contacts could be made if the KSC conflict meeting was used to look farther into the future. During Week 16, we should be determining the KSC conflicts for Week 19. That would permit better use of KSC and DSN resources. -------------------------------------------------------------- 7. Hikitsugi Items 7.1 Tohbans for week 17 SSOC: K. Matsuzaki, H. Nakajima KSC: M. Hagino, K. Kobayashi, S. Masuda 7.2 STT timer setting STT timer setting is due on Tuesday, 20-Apr-99 (JST) 7.3 Holiday Schedule The next holiday will be Sunday, 25-Apr (JST). 7.4 Elevation SSOC Tohbans need to examine the maximum elevation when checking the DSN final schedule, because the maximum elevation may change from the strawman to final schedule due to changing orbital elements. DSN requires a maximum elevation more than 7 degrees . This is listed in the English language manual, but not the Japanese language manual. If this information is put in the manual we can delete this item from hikitsugi. 7.5 KSC pass conflicts ASCA conflicts cause the loss of about 10 KSC contacts per week at this time We do not know which contacts Yohkoh will lose until the weekly meeting. Santiago contacts occur on the same orbits as KSC contacts. Therefore, keep as many Santiago contacts as possible in the DSN Strawman and Preliminary Forecasts. 7.6 SSOC Tohban Manual -- The command plan problem on 14-APR-99 is actually explained in the English SSOC tohban manual, and an example command sheet given. But the example is also confusing, as the ROG and the other commands are not grouped together. A note hase been sent to Sterling-san and the manual annotated. -- Better understanding of the meaning of commands would help avoid mistakes made from simple copying of command sheets. The file $DIR_GEN_ORBIT/og_lookup.ascii contains all the commands that OP_FIRST_GUESS ever puts into an OP. There are only 31. There are some other commands that are used on the command sheets; I counted 31 is scanning a number of recent weeks. There is some overlap of the two lists. A glossary of these common commands, with a 2 sentence explanation of the usage and effects of each, would only be 2 or 3 pages long and would be a valuable addition to the manual to refresh our memory. 7.7 Some Problems in OP_FIRST_GUESS -- The BDR optimization changes the DP mode between Quiet Medium and Quiet High. The algorithm chooses to end a contact in Medium rate, then switch to High rate later, to be in High rate for the next contact. During this week, the switch to High rate occurred just before entering SAA during orbit day in the following cases: 12-APR-99 16:20 UT 12-APR-99 21:28 UT 13-APR-99 16:35 UT 14-APR-99 20:02 UT 15-APR-99 15:23 UT 16-APR-99 13:40 UT (Short SAA, then terminator at 14:15) 17-APR-99 14:11 UT 19-APR-99 12:40 UT These cases seem very unfortunate in their choice of time to go to High rate. Perhaps the BDR optimization and SAA data rate parts of the code should be studied to see if an improvment is possible. 7.8 Campaigns There is an observing campaign with TRACE, Big Bear, Mees, and SXT for the next 2 weeks to observe an active region during its transit of the disk. 7.9 Discussions in WOM (12-APR-99) -- Yohkoh data distribution Distribution of data to sites in Japan and the US is slow at this time because of the limited manpower available to reproduce the tapes and/or CDs. With the improvement of network connections, perhaps a system of electronic distribution should be considered as a way to speed the distribution. -------------------------------------------------------------------------- 8. Action Items === END === ============ APPENDIX ============================== ============================================================================= To: SXT Weekly Meeting Subject: KSC and DSN contact counts From: Barry LaBonte At the 12-April-1999 meeting, Hudson asked for the statistics of the DSN contacts that Yohkoh received from the various stations. The survey of the most recent 5 weeks is given in TABLE 1. The table compares the Preliminary Forecast with the Final Schedule. Differences between the two should be caused by DSN requirements, rather than conflicts with other ISAS spacecraft. By comparison, some variation in the number of contacts in the Preliminary is caused by spacecraft conflicts that are resolved from the Strawman forecast. I have listed the KSC contacts as well, because they are a major part of our data downlink. The difference here is spacecraft conflict. We are very successful in getting Wallops and Santiago contacts, and not successful in getting Goldstone or Madrid contacts. Canberra overlaps Wallops, but is useful for filling gaps and we are successful in getting contacts. There is a correlation between the number of contacts requested and the number received: Ask and ye shall receive. Pass additions to Final were successful in Week 14; that was important because Week 14 had a low total number of contacts requested/received. With 104 orbits per week and 55 contacts per week, there are approximately 100+ minutes of daylight for every downlink. The BDR is over subscribed by more than a factor of 2 on average. Because the contacts are clustered around KSC times and Wallops times, the gaps between the two are much worse. Early in the mission, the DSN contacts at Goldstone, Canberra, and Madrid were spread more uniformly through the day, with fewer long gaps. Table 2 lists a measure over the mission of the data rate for receiving FFI and PFI images. The PFI rate shows the decrease and increase from flare activity. The FFI rate shows a steady decrease over time. I did not look to see if this is caused by a change in the proportion of Half-Res and Quarter-Res, for example. I did a quick survey of contacts during several weeks in late 1993 and early 1994. At that time we had 30 KSC contacts per week and between 35 and 54 DSN contacts per week, for a total of 65 to 84 contacts per week. The difference of about 10 contacts in the most recent weeks is the loss of KSC to other spacecraft. The number of DSN contacts is about the same. =============================================================================== TABLE 1 Station Preliminary Final Notes Week Week 13 14 15 16 17 13 14 15 16 17 _______________________________________________________________________________ U 30 30 30 30 30 19 18 19 21 21 G 0 0 1 7 1 0 0 1 0 1 C 6 2 6 5 0 5 2 4 2 0 1 M 0 1 2 16 11 0 3 1 1 8 2 S 6 4 0 8 14 2 4 0 6 13 3 W 28 25 28 30 32 28 24 27 28 32 ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- Total 70 62 66 96 86 54 51 52 58 75 Rev/week = 104 ------------------------------------------------------------------------------ Station Key: Abbreviation Name Antennas Percent received U KSC 66 ( 98 / 150) G Goldstone 16, 17 22 ( 2 / 9) C Canberra 46 68 ( 13 / 19) M Madrid 66 43 ( 13 / 20) S Santiago 74 84 ( 27 / 32) W Wallops 76, 80, 82 97 (139 / 143) Notes: 1. Deleted 1 contact in Final W13; received 0 of 1 addition request W14. 2. Received 2 of 4 addition request W14. 3. Deleted 4 contacts in Final W13; 1 in Week 16; 1 in Week 17. ------------------------------------------------------------------------------- =============================================================================== TABLE 2 Long term SXT data rate, average of 3 winter months (Dec-Feb or Jan-Mar) 1993 6900 FFI per month 38000 PFI per month 1994 7100 " 50000 " 1995 6600 " 26000 " 1996 6500 " 26000 " 1997 6500 " 24000 " 1998 6100 " 29000 " 1999 5700 " 38000 " ------------------------------------------------------------------------------ ==============================================================================