7 December 1998 Mark Weber Hugh Hudson SXT CHIEF OBSERVER'S REPORT AND TABLE PLAN CHIEF OBSERVER'S REPORT for Week 51 14-Dec-98 to 20-Dec-98 GENERAL Yohkoh and SXT continued to perform without problems this week. Solar activity was at a high background level most of the week, hovering near the C1 level. There were only two M flares as of Saturday, but the flares that did occur had strikingly impulsive time profiles. As yet we don't know about Yohkoh coverage of the really interesting event, Dec. 18, but based on the ephemeris it looks good. We'll try to reformat the data by Monday evening. SXT TECHNICAL The SXT instrument is functioning nominally. 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/981218.html Index: http://www.solar.isas.ac.jp/sxt_co/index.html This week's science nugget deals with nearly homologous "three-legged flares", and proposes an alternative physical explanation for them. Next week's nugget (981225.html) is also on line and is even more interesting. Merry Christmas, Yohkoh. CAMPAIGNS There were no formal joint observing campaigns this week. A VLA/TRACE study did not fall within our visible window. We only heard about the VLA time third-hand, so we've initiated an effort to improve general coordination. There is an official Web page for this purpose, maintained by Alan Kiplinger: http://sec.noaa.gov/solcoord/solcoord.html PERSONNEL Nothing to report. SEMINARS Two talks this week: G. Hanoun (Independent/RAL) "Advances in Computer Simulation and Visualization in Solar Flare Research" H. Hudson (SPRC/ISAS): "Ejecta from the X-class Flares of the New Cycle" 21 December 1998 M. Weber, H. Hudson SXT TABLE PLAN, WEEK 52 (20-Dec-98 --- 26-Dec-98) We know of no particular plans for coordinated observations, but will keep our eyes on TRACE and CDS as usual. TRACE has started to send their operation plans again. ________________________________#_______________________________ JST Day UT Start Time Pass Table ID Monday 21-DEC-98 06:49 3 981221 P3 ARS1 DARKCAL Tuesday 22-DEC-98 07:06 4 981222 P4 ARS1 STD Wednesday 23-DEC-98 05:39 3 981223 P3 ARS1 STD Thursday 24-DEC-98 04:12 2 981224 P2 ARS1 STD+DIFF " 24-DEC-98 09:22 5 981224 P5 ARS1 STD Friday 25-DEC-98 02:46 2 981225 P2 ARS1 STD Saturday 27-DEC-98 03:02 2 981226 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.