12 April 1999 Nariaki Nitta CHIEF OBSERVER'S REPORT for Week 15 5-Apr-99 to 11-Apr-99 GENERAL Solar activity was modest with one M-class flare. Bright regions included AR 8506 and AR 8508, which were also observed by TRACE. Among the phenomena that caught one's attention were trans-equatorial loops between AR 8507 and an area without nummber in the southern hemisphere and reverse jets north of AR 8510. SXT TECHNICAL Scientists involved in the analysis of the 20-Jan-99 flare (for a preliminary report, see http://www.solar.isas.ac.jp/sxt_co/990122.html ) continued working on vignetting to see how appropriate the corrections are as provided by the program ``SXT_VIGNETTE.'' 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/990409.html Index: http://www.solar.isas.ac.jp/sxt_co/index.html This week's Science Nugget gives a quick analysis of the recent trans-equatorial loops, which appeared to shrink. CAMPAIGNS We dedicated 1-2 passes a day for four days to observed the TRACE target regions for Jim Klimchuk's study of loop width. 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 Barry LaBonte arrived for a two-week visit, just in time for expected work on vignetting and scattering. Phil Shirts departed, but everybody hopes he will return pretty soon. SEMINARS There were two presentations at the Yohkoh seminar on 8 April. Speakers and titles were: A.C. Sterling (CPI/NRL/ISAS) "'S' Marks the Spot - the NASA Video" <=== K. Shibasaki (NRO) "Radio Detection of Umbral Oscillations" SXT TABLE PLAN, WEEK 16 (11-Apr-99 to 17-Apr-99) We coordinate with SoHO JOP 100 (radio magnetometry) on Tuesday, followed by a CCD bakeout on Wednesday/Thursday. When are we going to know the dates of another TRACE AR tracking? Note that there will be a SUMER campaign to observe jets on the west limb, starting 3-May-99. At the ops meeting, we briefly discussed the possibility of using the last contact of the day for a table upload, given the decreasing number of contacts allocated to Yohkoh as a result of the overlap of its orbit with other ISAS satellites. We were told that KSC tohbans are generally trained for emergency, and therefore that it is probably OK to use the last contact. ________________________________#_______________________________ JST Day UT Start Time Pass Table ID Monday 11-Apr-99 23:31 2 990411 P2 ARS2 VLA Monday 11-Apr-99 01:14 3 990411 P3 ARS2 VLA Tuesday 12-Apr-99 22:04 1 990412 P1 ARS2 VLA Tuesday 13-Apr-99 01:30 3 990412 P3 ARS1 STD Wednesday 13-Apr-99 20:38 1 990413 P1 ARS0 BAKEOUT Thursday 15-Apr-99 02:01 4 990414 P4 ARS1 DAR Friday 15-Apr-99 21:07 2 990415 P2 ARS1 DIFF Saturday 16-Apr-99 21:22 2 990416 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.