23 October 1999 D. McKenzie L. Fletcher CHIEF OBSERVER'S REPORT for Week 43 18-Oct-99 to 23-Oct-99 GENERAL Solar activity has remained low all week. The GOES X-ray baseline remained at high B and low C level. Several C-class flares were recorded, and an M1.9 event on 20-Oct-99 06:00 UT. High levels of geomagnetic activity were recorded on 22-Oct-99. SXT TECHNICAL The instrument continued to perform well all week. The flare-trigger threshold was lowered to the level used for the first 8 years of the mission, to set the flare flag at approximately C2-C3 on the GOES scale. A high stray-light count on 21-Oct-99 was tracked down to blooming of the CCD serial registers onto the illuminated part of the chip; a problem which has occurred a few times over the last weeks when the narrow-band filter is being used for straylight monitor images. This is possibly related to insufficient CCD flushing preceding NaBan images, and is under investigation. Because subsequent straylight-monitor images do not show an elevated level, we are confident that a new entrance filter rupture has NOT occurred at the present time. For Web material see Current Week: http://isass1.solar.isas.ac.jp/sxt_co/991022.html Index: http://isass1.solar.isas.ac.jp/sxt_co/index.html This week's science nugget describes an M flare successfully observed by SXT/TRACE/SoHO/GBO JOP113 CAMPAIGNS For SXT plans, see: http://isass1.solar.isas.ac.jp/sxt_co/sxt_future.html For SXT completed campaigns, see: http://isass1.solar.isas.ac.jp/sxt_co/sxt_catalog.html PERSONNEL At the beginning of the week, Hugh Hudson travelled to GSFC for the HESSI workshop. At the end of the week, Phil Shirts returned to Palo Alto. SEMINARS There was no seminar this week. SXT TABLE PLAN, WEEK 44 (25-Oct-99 to 30-Oct-99) This week continues joint flare observations with SUMER and TRACE, among others. See http://isass1.solar.isas.ac.jp/sxt_co/sxt_future.html for details. Expect to use ARS2 most of the week, and PFI-dominant for a few orbits on Wednesday, Thursday, and Saturday. Note that this may be changed. ________________________________#_______________________________ JST Day UT Start Time Pass Table ID Monday 25-OCT-99 05:05 3 991025 P3 ARS2 FLARE SPEC Tuesday 26-OCT-99 00:11 1 991026 P1 ARS2 DARK+FLARE Wednesday 27-OCT-99 02:06 2 991027 P2 ARS0 FLARE SPEC Wednesday 27-OCT-99 05:31 4 991027 P4 ARS2 DIFF+FLARE Thursday 27-OCT-99 22:55 1 991027 P1 ARS0 FLARE SPEC Thursday 28-OCT-99 02:19 3 991027 P3 ARS2 FLARE SPEC Friday 29-OCT-99 02:32 3 991029 P3 ARS2 FLARE SPEC Saturday 29-OCT-99 21:40 1 991029 P1 ARS0 FLARE SPEC Saturday 30-OCT-99 01:03 3 991029 P3 ARS1 STD NOTE THAT SOME OF THE TABLE ID NAMES LOOK STRANGE. This is because of the convention of naming each table according to the UT date of the FIRST PASS OF THE KSC DAY. This plan is subject to change. Continuing requests: KSC & SSOC Tohbans: If any KSC passes are likely to be cancelled (for example due to a typhoon) or an SXT table cannot be uploaded for some reason, please telephone and e-mail the Chief Observer immediately. (sxt_co@isass0.solar.isas.ac.jp, copy to sxt_st@flare2.solar.isas.ac.jp). SSOC Tohban: On the weekly visible diagram, please mark the official five passes first and then cross out those passes that will be given to other satellites. That way we can keep the numbering straight in the Yohkoh software system. SSOC Tohban: SXT operations do not currently include terminator off- pointing. It is unnecessary this week to ask the SXT Chief Observer for terminator off-pointing information. KSC Tohbans: In general flare mode supersedes table upload, i.e. if a flare is in progress please do not upload a new table, and contact the chief observer. Normally it is OK to go ahead with the planned table without change on the next pass, if it is available. Chief observers should keep an eye on this.