March 14, 1999 Hugh Hudson CHIEF OBSERVER'S REPORT for Week 11 8-Mar-99 to 14-Mar-99 GENERAL SXT continues to perform properly. Terminator image acquisition proceeds. Solar activity remained at a low level, with several M flares not observed well by Yohkoh. The weekly science nugget takes a second look at the X-class flare of May 2, 1998. However there was a halo CME on March 11 that would be worth attention. SXT TECHNICAL A normal pointing update took place Friday night. This caused a perceptible change in the total stray-light signal. Acton proposes moving the normal pointing to the south, in order to avoid the bright SW pinhole in the new configuration. If it is OK, the SXT CO will do some pointing experiments this week, and then when we have a full terminator collection for the current normal pointing position, we will adjust it. the distance would probably be on the order of 30 arc sec, mainly to the S. There were a great many errors in SXT_CO work last week, especially in the faxed descriptions of the table uploads. Sorry about that! There were no major problems in actual function. SXT SCIENCE The big news this week, of course, was Alphonse's starring role ("S marks the spot!") in Dick Canfield's sigmoid spectacular Space Science Update. The science behind this is the detectability of pre-CME sigmoid signatures in active regions. There are several science nuggets on this topic, or see http://solar.physics.montana.edu/press/ and http://solar.physics.montana.edu/press/release.html for fuller details. For routine 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/990312.html Index: http://www.solar.isas.ac.jp/sxt_co/index.html The current Nugget shows signatures of helicity related to the X-class flare of May 2, which is a candidate for MDI wave detection. CAMPAIGNS We coordinated with Neale Ranns for CDS/TRACE observations aimed at flare precursors (JOP098). This meant a good deal of ARS2. One has to wonder if there is a sigmoid signature detectable... there were many microflares in the region studied. 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 Tom Metcalf came and went, helping substantially with SXT CO work. SEMINARS None this week because of Solar-B. SXT TABLE PLAN, WEEK 12 (15-Mar-99 to 20-Mar-99) There are no scheduled joint observing campaigns this week, so we will just try to keep up with TRACE and CDS informally, as usual. ________________________________#_______________________________ JST Day UT Start Time Pass Table ID Monday 15-MAR-99 14:31 3 990315 P2 ARS1 STD Tuesday 16-MAR-99 16:29 4 990316 P4 ARS1 DAR (*) Wednesday 17-MAR-99 11:37 2 990317 P2 ARS1 DIF Thursday 18-MAR-99 11:53 2 990318 P2 ARS1 STD Friday 19-MAR-99 12:08 3 990319 P3 ARS1 STD Saturday 20-MAR-99 12:24 3 990320 P3 ARS1 STD (*) => table name adopts the convention of UT date of first pass, so that the UT day and JST day for that pass don't match. 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.