SXT Status Report 8 January 1996 - 4 March 1996 (Weeks 01 - 09) ---------- Serge Savy 4-Mar-96 SXT operations have been straightforward. We have carried out some special operations aimed at observing filament eruptions and the quiet corona. In addition obervations of bright points were carried out in coordination with the VLA. SOLAR ACTIVITY The Sun has been quiet with no major flares. Towards the end of February activity increased with the appearance of a nice active region (AR7946) associated with a significant filament. It was interesting to watch a large swath of diffuse corona that persisted for the first few weeks in February at the location of a large filament. SXT INSTRUMENT STATUS The SXT instrument has continued to work well. There were no significant SXT errors. SXT continued to observe, without interruption, during the replacement of the ISAS main-frame computers (February 17-24). SXT CALIBRATION ACTIVITIES The main effort for SXT calibration continues to be the "terminator" program, whereby correction images are obtained by acquiring pictures when the X-ray sun has set but the visible sun is unaffected by atmospheric absorption. These images still show the scattered optical light, and we have found that excellent corrections for this effect can be made by proper use of the terminator data. We continue to work on ways of getting such correction images efficiently and in the right filters. PASS CONFLICTS Week 2: 7 KSC passes lost to ASUKA, 7 lost to SFU recovery. Week 3: 5 KSC passes lost to ASUKA. No passes were lost to SFU, which was safely brought back to the ground after being pick up by the Shuttle. There will be no more passes lost to SFU. Week 4: 7 KSC passes lost to ASUKA. Week 5: 6 KSC passes lost to ASUKA. Week 6: 8 KSC passes lost to ASUKA. Week 7: 6 KSC passes lost to ASUKA. Week 8: 6 KSC passes lost to ASUKA. We also lost 2 real-time DSN contacts due to support of the POLAR launch, but received one real-time DSN contact addition in lieu. Week 9: 8 KSC passes lost to ASUKA. CAMPAIGNS From the launch on 7 January of the Flare Genesis Balloon we were in communication the operations team in Antarctica on a daily basis in attempt to coordinate observations. However, problems with pointing of the Flare Genesis telescope prevented them from tracking the active region that SXT was observing. As part of a campaign to observe X-ray bright points, flares and jets in coordination with VLA, AR7946 was the PFI target on 24 February and the North Polar region was observed on 29 February. SCIENCE There have been many visitors at ISAS/Yohkoh. Richard Schwartz (GSFC) was present for three weeks to analyze the HXT data from the 13 Oct 1995 flare during which HXT was operated in calibration mode, and thus, obtained higher spectral resolution data, instead of high-time resolution spatial data. Richard has submitted a paper to upcoming HEAD meeting. Other visitors included Richard Canfield (U of Hawaii); Robert Rosner, Vinay Kashyap, and Christof Litwin (U of Chicago); and David Webb (Boston College). Lemen worked with Hudson and Webb on the 21 Feb 1992 and the 28 Dec 1992 large scale eruption events, which are likely to be the X-ray signatures of a CME. Webb pointed out a beautiful example of "coronal dimming" in the apparent launch of a CME on Aug. 28, 1992; this then became one of the centerpieces of publicity at the time of the Chapman conference on magnetic storms (JPL). See the SDAC home page on WWW for further details. Giovanni Peres (Palermo) visited for about ten days, concentrating on learning about systematic effects in temperature determinations as an input to the program of understanding "the Sun as a star" in the X-ray domain. SEMINARS Wednesday 10 January: H. Negoro (ISAS) on "X-ray fluctuations in black hole candidates in comparison with solar flares". This is part of a general effort to do improved timing analyses on solar X-rays, stimulated by such things as "avalanche theory" and by the QPO phenomenon in X-ray astronomy. Wednesday 17 January: H. Hudson (ISAS) and R. Schwartz (GSFC) reviewed the recent Markus Aschwanden papers that studied the timing of X-ray bursts using BATSE data for eight events studied by Sakao-san in his thesis. The analysis makes excellent use of the large-area BATSE counters and Yohkoh imaging. Wednesday 31 January: R. Canfield discussed the subject of current helicity or twist as observed in the Mees vector magnetograph data and in the SXT images. Helicity seems to be the common language used in the solar interior, the atmosphere, and interplanetary space! PERSONNEL Nariaki Nitta arrived at the beginning of February for a one month stay. James Lemen and Gary Linford left after a one month stay. Gary re-organised disc space on the ISAS machines and made system backups, among other useful things. Lemen was SXT Chief Observer for most of January. Week 02 Tohbans: SSOC: S. Nagata, S. Yuda KSC: J. Sato, E. Ueta SXT Chief Observer: S. Savy, H. Hudson SXT Systems and Data Engineer: G. Linford Week 03 Tohbans: SSOC: K. Akita, T.Ishii KSC: E. Ueta, K. Hori SXT Chief Observer: J. Lemen SXT Systems and Data Engineer: G. Linford Week 04 Tohbans: SSOC: M.Sawa, M.Miyashita KSC: K.Hori, S.Yashiro SXT Chief Observer: J. Lemen SXT Systems and Data Engineer: G. Linford Week 05 Tohbans: SSOC: H. Hudson, J. Lemen KSC: K. Fujiki, S. Yashiro SXT Chief Observer: S. Savy SXT Systems and Data Engineer: G. Linford Week 06 Tohbans: SSOC: A. Sterling, K. Ichimoto KSC: K. Fujiki, S. Kawashima SXT Chief Observer: S. Savy SXT Systems and Data Engineer: G. Linford Week 07 Tohbans: SSOC: T. Watanabe, K. Akita KSC: S. Kawashima, R. Kano SXT Chief Observer: S. Savy SXT Systems and Data Engineer: Week 08 Tohbans: SSOC: K. Shibasaki KSC: R. Kano, S. Morita SXT Chief Observer: S. Savy SXT Systems and Data Engineer: Week 09 Tohbans: SSOC: S. Ueno, S. Tsuneta KSC: S. Morita, S. Kubo SXT Chief Observer: N. Nitta SXT Systems and Data Engineer: