12 September 1999 N. Nitta CHIEF OBSERVER'S REPORT for Week 37 6-Sep-99 to 12-Sep-99 GENERAL Solar activity was not high, with the GOES X-ray background fluctuating between B2 and B4. Small active regions dominated. Observation of the only M-class flare (on 8-Sep-99) was interrupted in the early phase due to a DSN downlink. SXT TECHNICAL Regarding a higher threshold for the flare mode trigger, the above flare was observed from quite early in flare mode. We should observe a few more to finalize the level. SXT SCIENCE Peter Sturrock visited, and gave a nice seminar and an informal discussion session on mean-field dynamo theory. For Web material see Current Week: http://isass1.solar.isas.ac.jp/sxt_co/SXTweekly.html Current Week: http://isass1.solar.isas.ac.jp/sxt_co/990910.html Index: http://isass1.solar.isas.ac.jp/sxt_co/index.html This week's science nugget shows a first analysis of X-ray/EUV ejection associated with the 25-Jul-99 flare/CME. 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 No change. SEMINARS On 9 September there was a Yohkoh seminar. Speaker: Peter Sturrock, Title: Chromospheric Magnetic Reconnection and its possible relationship to Coronal Heating. Various processes associated with magnetic cancellation were discussed. Very high quality and educational seminar. We should have this sort every week. SXT TABLE PLAN, WEEK 38 (13-Sep-99 to 19-Sep-99) This week, if solar activity continues to be low, we may further explore the observing sequences for interconnecting loops (IL) as proposed by Joe Khan. ________________________________#_______________________________ JST Day UT Start Time Pass Table ID Tuesday 13-Sep-99 22:57 3 990913 P3 ARS1 DARK Wednesday 14-Sep-99 19:47 1 990914 P1 ARS0 IL+DIFF Wednesday 15-Sep-99 00:54 4 990914 P4 ARS1 STD Thursday 15-Sep-99 18:20 1 990915 P1 ARS0 IL-VER0 Thursday 15-Sep-99 21:42 3 990915 P3 ARS1 STD Friday 16-Sep-99 18:32 1 990916 P1 ARS0 IL-VER0 Friday 16-Sep-99 21:56 3 990916 P3 ARS1 STD Saturday 17-Sep-99 18:45 1 990917 P1 ARS0 IL+STD Saturday 17-Sep-99 22:10 2 990917 P3 ARS1 STD 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.