01 May 1999 David McKenzie Hugh Hudson CHIEF OBSERVER'S REPORT for Week 18 25-Apr-99 to 01-May-99 GENERAL Solar activity remained low this week, though better than last week. The GOES background increased to the middle-B range, and a number of flares were detected: several "C", and one "M". A halo CME was observed by LASCO in connection with the M-flare, which came from the S-shaped region AR 8524. SXT TECHNICAL SXT continues to operate smoothly. We have ascertained that some small increases to the stray light have occurred in the last month, probably due to incremental entrance filter ruptures. We are continuing to make terminator images. Also, we are near the saturation limit of the (NaBan/Open + Dark) straylight monitor images, and so we will experiment with different filter combinations to find an alternative straylight monitor configuration. An update to the normal pointing was performed this week; we will ask for another normal pointing update this week. 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/990430.html Index: http://www.solar.isas.ac.jp/sxt_co/index.html This week we are comparing SXT and EIT images of bright linear "rays" above an active region. CAMPAIGNS SXT continued ARS2 support of the BBSO/Mees/SOHO/TRACE observations of AR 8518 until Friday. 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 David McKenzie arrived for a 5-week stay, Dick Canfield arrived for a 2-week stay. SEMINARS There was an informal Yohkoh seminar on 28 April, in which McKenzie led a discussion about the 20-jan-99 flare arcade event and the structures and motions detected therein. This is exciting evidence (in the opinion of some) of high-speed flows in the region just above flare loops. Also, Hudson reviewed two articles by Bothmer et al. and Larson et al., regarding the use of interplanetary particle detections to understand the conectivities of magnetic flux ropes. SXT TABLE PLAN, WEEK 19 (3-May-99 to 8-May-99) This week begins a two-week campaign with SUMER, CDS, TRACE, and Tenerife, to look for X-ray jets from limb active regions. This will be called JOP 104. We will probably run in ARS2 mode all week; on Tuesday, Wednesday, and Friday nights we will try to make some PFI-dominant runs. ________________________________#_______________________________ JST Day UT Start Time Pass Table ID Monday 03-May-99 13:42 2 990503 P2 ARS2 ST+J104 Tuesday 04-May-99 13:57 2 990504 P2 ARS2 ST+J104 (PFI DOM) Wednesday 04-May-99 17:23 4 990504 P4 ARS2 DK+J104 Wednesday 05-May-99 12:30 2 990505 P2 ARS2 DF+J104 (PFI DOM) Thursday 05-May-99 15:55 4 990505 P4 ARS2 ST+J104 Thursday 06-May-99 12:45 2 990506 P2 ARS2 ST+J104 Friday 07-May-99 11:18 2 990507 P2 ARS2 ST+J104 (PFI DOM) Friday 07-May-99 14:43 4 990507 P4 ARS2 ST+J104 Saturday 08-May-99 11:33 2 990508 P2 ARS1 STD The "J104" in the name refers to JOP 104. 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.