9 January 1999 Hugh Hudson David McKenzie SXT CHIEF OBSERVER'S REPORT AND TABLE PLAN CHIEF OBSERVER'S REPORT for Week 02 02-Jan-99 to 09-Jan-99 GENERAL SXT continues to perform properly. Solar activity decreased precipitously owing to the rotation beyond the W limb of the huge region AR 8421. Much to our surpise, an over-the-limb event then occurred on the S, no the N, from the equally rotated but not so impressive AR 8422. SXT TECHNICAL The SXT instrument is functioning nominally, no serious problems to report. This is good because this is the first SXT report since Yohkoh emerged from the New Year's holiday. One item, however: immediately after operations resumed, we found three false flare triggers in a row, one in each of the (M-rate) orbits preceding the first BDR dump at KSC. These were due to grazing passages through the SAA; the SXS flare trigger is working OK. Either the SAA had changed a bit, or our orbit predictions were off a bit, probably the former; let us keep an eye on this. In the meanwhile we got some patches of high-rate data on AR 8421 in case anybody is interested. SXT SCIENCE For Web material see Current Week: http://www.solar.isas.ac.jp/sxt_co/SXTweekly.html Current Week: http://www.solar.isas.ac.jp/sxt_co/990108.html Index: http://www.solar.isas.ac.jp/sxt_co/index.html This week's nugget shows a contrasting pair of coronal holes, one with a whorl, and poses a question about connectivity. CAMPAIGNS There were no formal joint observing campaigns. SOHO is temporarily offline again. See the general coordination page at: http://sec.noaa.gov/solcoord/solcoord.html PERSONNEL David McKenzie arrived, and Mark Weber returned to Montana, both on 6-jan. SEMINARS There was no seminar this week. DRAFT SXT TABLE PLAN, WEEK 03 (11-Jan-99 to 17-Jan-99) No coordinated observations are currently planned. ________________________________#_______________________________ JST Day UT Start Time Pass Table ID Monday 10-JAN-99 19:24 2 990110 P2 ARS1 STD Tuesday 11-JAN-99 19:41 2 990111 P2 ARS1 DARKCAL Wednesday 12-JAN-99 18:14 2 990112 P2 ARS1 STD Thursday 13-JAN-99 16:48 1 990113 P1 ARS1 DIFF Thursday 13-JAN-99 21:56 4 990113 P4 ARS1 STD Friday 14-JAN-99 17:04 2 990114 P2 ARS1 STD Saturday 15-JAN-99 17:20 2 990115 P2 ARS1 STD Sunday 16-JAN-99 15:54 2 990116 P2 ARS1 STD 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, ie 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.