12 September 1998 Nariaki Nitta SXT CHIEF OBSERVER'S REPORT AND TABLE PLAN CHIEF OBSERVER'S REPORT for Week 37 7-Sep-98 to 13-Sep-98 SOLAR ACTIVITY Solar activity was not low after all, with two M-class and many C-class flares. During the first half of the week, we spent most of our time observing AR 8323, in coordination with the Meudon/Tenerife campaign. There was an obvious filament disappearance (7-Sep-98) to the northeast of AR 8323, not leaving spectacular X-ray signatures. The first M-class flare, on 9-Sep-98, occurred in AR 8323, but escaped our observations in PFIs due to a simultaneous brightening in another region (AR 8331). In FFI data, we noted trans-equatorial loops between AR complex 8326/8327/8329 and AR 8328, and between AR 8333 and an unnumbered region in the southern hemisphere. But no such loops were seen between AR 8331 and AR 8330. SXT INSTRUMENT STATUS The SXT instrument continued to work fine. Three bitmap errors occurred, but each of them was cleared at the same pass. SXT SCIENCE For Web material see Current Week: http://www.solar.isas.ac.jp/sxt_co/SXTweekly.html Index: http://www.solar.isas.ac.jp/sxt_co/index.html The science nugget (week 98_37) shows an attempt of understanding the geometry of flare loops. CAMPAIGNS Second week of the Meudon-Tenerife campaign. PERSONNEL Jean-Pierre Wuelser arrived from Palo Alto, and will be here until 2-Oct. George Simnett returned to Birmingham after a three-month stay as a guest professor. SEMINARS 10-Sep-98 G. Simnett (U. Birmingham): "CIRs: Interpretations and Modulation of Cosmic Rays" TABLE PLAN, WEEK 38 (14-Sep-98 - 20-Sep-98) SXT Chief Observer: Nitta/Hudson At least three SOHO campaigns were planned for this week, but we do not know if they are still planned, except for the one proposed by Karin Muglach. She will deal with the topic ``Structure of Sunspots'', but her assigned times are largely outside Yohkoh visible orbits. ________________________________#_______________________________ JST Day UT Start Time Pass Table ID Monday 14-Sep-98 06:06 3 980914 P3 ARS1 DARKCAL Tuesday 15-Sep-98 01:18 1 980915 P1 ARS2 SPOT Tuesday 15-Sep-98 06:23 4 980915 P4 ARS1 STD Thursday 17-Sep-98 01:51 1 980917 P1 ARS2 SPOT Thursday 17-Sep-98 06:59 2 980917 P4 ARS1 STD DIF Friday 18-Sep-98 00:26 1 980918 P1 ARS2 SPOT Friday 18-Sep-98 05:33 4 980918 P4 ARS1 STD Saturday 19-Sep-98 02:25 2 980919 P2 ARS1 STD Note that this plan may change during the week. 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.