19 April 1999 Hugh Hudson CHIEF OBSERVER'S REPORT for Week 16 12-Apr-99 to 18-Apr-99 GENERAL Solar activity dropped again, with barely a C-class flare or two. One interesting item was the dark "notch" between highly inclined large-scale loops in AR 8508, probably the topic for next week's science nugget. Trans-equatorial loops came and went. SXT TECHNICAL The long-awaited and twice scrubbed CCD bakeout took place on Friday. This was successful and should be repeated in about June or July. The dark current dropped very slightly and we await some analysis of the image quality. A major bug in SXTSPT was found (by Nitta) and fixed (by Hara and contractors). 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/990416.html Index: http://www.solar.isas.ac.jp/sxt_co/index.html This week's Science Nugget comments on a CME event from April, 1997, which provides us with some experience for the forthcoming SUMER campaign. It was interesting in that the X-ray counterpart was not an LDE. CAMPAIGNS SXT conducted joint observations with SOHO, TRACE, and the VLA for loop characterization. Please see the general coordination page at: http://sec.noaa.gov/solcoord/solcoord.html For SXT plans, finger campaign@isass0.solar.isas.ac.jp. PERSONNEL Nariaki Nitta departed, having set a new record in SXT table generation rate. SEMINARS There were two presentations at the Yohkoh seminar on 15 April: B.J. LaBonte (U. Hawaii): "Vector Magnetic Fields in AR 8210" N. Nitta (LMSAL): "The Geometry of Flare Loops" These both dealt with the fundamentally important question of the true 3D structure linking the photosphere and corona. LaBonte's talk featured an actual movie of vector magnetograms from an AR that produced X-class flares (e.g. May 2, May 6). ^L SXT TABLE PLAN, WEEK 17 (18-Apr-99 to 23-Apr-99) The long-awaited TRACE active-region stare began on Saturday, but with only a weak region to look at (8516). We expect that a new region might be selected, but there is not much to choose from right now! The table plan thus reflects a steady diet of ARS2 tables. ________________________________#_______________________________ JST Day UT Start Time Pass Table ID Monday 18-Apr-99 20:09 2 990418 P2 ARS2 STARE* Tuesday 19-Apr-99 20:24 2 990419 P2 ARS2 STADA* Wednesday 20-Apr-99 18:57 2 990420 P2 ARS2 STADI* Thursday 21-Apr-99 19:12 2 990421 P2 ARS2 STARE* Friday 22-Apr-99 19:27 2 990422 P2 ARS2 STARE* Saturday 23-Apr-99 19:42 3 990423 P3 ARS2 STARE* 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.