SXT Status Report September 28 through October 19, 1998 (Weeks 40-42) H. Hudson, D. McKenzie, J.-P. Wuelser SUMMARY Activity was low. There were no technical problems for Yohkoh or for SXT. SXT conducted some coordinated observations with TRACE and ground-based observatories. SOHO has returned! SOLAR ACTIVITY The GOES background level (see the plots, for example, on our weekly SXT Web pages at http://www.solar.isas.ac.jp/sxt_co/index.html) remained around the mid-B level. There were four or five M flares, but no outstanding activity. The Sep. 23 flare reported in the last SXT status report finally arrived iN good form from Canberra, thanks to Seko-san's unrelenting efforts. It was worth the wait in terms of beautiful eruptions flying off in almost all directions. Take a look at the data; sorry we haven't done any reductions, but views of the raw data in the half- and quarter-resolution sequences are worth the effort for those familiar with YODAT and STEPPER in the Yohkoh SolarSoft library. OBSERVING CAMPAIGNS The joint observing campaign with J. Singh at Norikura, plagued by clouds, may finally have been rewarded by one day's observation of the NE limb. This was also coordinated through TRACE. SOHO is back; LASCO observed a halo CME resulting from the event of Sep. 15 - not visible in GOES, it was a spectacular quiet-Sun arcade development as seen by SXT. SXT INSTRUMENT STATUS AND CALIBRATION ACTIVITIES Another redefinition of the Yohkoh "normal pointing" position was performed Oct. 4, in order to optimize the collection of stray-light correction images. We have not yet implemented Acton's suggestion of _anticipating_ the routine seasonal and secular variations of Yohkoh pointing, which have been quite amazingly stable over the seven years, so we are still correcting the pointing by hand. It is now reported via the SXT functionality Web pages on ftp://isass5.solar.isas.ac.jp/pub/sxt_co/quick/quick.html, along with many other technical status items. Wuelser's patches to the HXA inputs for the Yohkoh coalignment system are working routinely, but we are still worried about the degradation of precision based on the HXA limb addresses. Wuelser's breakthrough in terms of "correlation tracking" on the full HXA 1-D images remains to be implemented and looks like a bit of a software development. SXT OBSERVING SEQUENCE TABLES ----------------------------------------------------------------- JST Day UT Start Time Pass Table ID ================================================================= Monday 27-SEP-98 23:54 3 980927 P3 DARKCAL Tuesday 28-Sep-98 20:45 2 980928 P2 ARS1 DIF Wednesday 29-Sep-98 21:02 2 980929 P1 ARS2 NELIMB # Intended for pass 1, uploaded on pass 2 Wednesday 30-Sep-98 00:28 4 980929 P4 ARS1 STD Thursday 30-Sep-98 17:55 1 980930 P1 ARS2 NORI Friday 1-Oct-98 18:12 1 981001 P1 ARS2 TRACE Saturday 2-Oct-98 20:11 3 981002 P3 ARS2 NELIMB Sunday 3-Oct-98 18:45 2 981003 P2 ARS2 TRACE Tuesday 5-OCT-98 21:01 4 981005 P4 ARS2 DARK+TRACE Wednesday 6-OCT-98 19:36 3 981006 P2 ARS2 DIF+TRACE # Intended for pass 2, uploaded on pass 3 Thursday 7-OCT-98 18:09 3 981007 P4 ARS2 TRACE Friday 8-OCT-98 20:10 4 981008 P4 ARS2 STD Saturday 9-OCT-98 18:44 4 981009 P4 ARS2 STD Sunday 10-OCT-98 19:01 4 981010 P4 ARS2 STD Wednesday 13-Oct-98 16:26 4 981013 P2 ARS1 DARKCAL Thursday 14-Oct-98 13:17 2 981014 P2 ARS1 DIFF Friday 15-Oct-98 13:34 2 981015 P2 ARS1 STD Saturday 16-Oct-98 15:35 4 981016 P4 ARS1 STD Note: the table upload activity diminished during weeks 41-42 because of special operations at KSC on behalf of other spacecraft, and because of Typhoon #10. There were a few operations problems at KSC, sometimes interrupting the reporting and/or data flow. These included a lightning strike on Oct. 6, and the major typhoon Oct. 17-19. The latter required special efforts by the tohbans to create multiple OP and command options to work around whatever Nature could do. Special thanks to Yoshida_san at SSOC, completing his second week of tohban work with this great complication, and to inexperienced tohbans at KSC who held up well against the elements. SCIENCE The Astronomical Society of Japan met during week 40, and there was another conference at Hida Observatory during week 42. A major international conference will occur during week 44 at Kiyosato (near the Nobeyama Radio Observatory). This has meant much activity in preparing and doing presentations. There were no ISAS seminars during these three weeks. The weekly science nuggets embedded in the SXT operations reports consisted of: 2-Oct-98: Flare with a cool loop-top source 9-Oct-98: A potpourri of solar activity 16-Oct-98: Yohkoh and the Neupert Effect The URL's for these and for the full list of science nuggets can be found on http://www.solar.isas.ac.jp/sxt_co/index.html, and the current week is also always kept on http://www.solar.isas.ac.jp/sxt_co/SXTweekly.html. OPERATIONS ISSUES T. Yoshida fixed a bug in the Wallops scheduling software. VISITORS AND PERSONNEL Greg Slater and Jean-Pierre Wuelser returned to Palo Alto; David McKenzie arrived from Montana; Hugh Hudson was absent for a week. SEMINARS None scheduled during this interval because of conflicting meetings. TOHBANS (spacecraft operators) Tohbans for Week 40 SSOC : Sawa, Hudson KSC : Takahashi, Hagino SXT_CO: Hudson SXT_SW: Slater Tohbans for Week 41 SSOC : Yamaguchi_T, Yoshida KSC : Hagino, [Sasaki] SXT_CO: McKenzie SXT_SW: - Tohbans for Week 42 SSOC : Yoshida, McKenzie KSC : Morimoto, Sasaki SXT_CO: Hudson SXT_SW: -