SXT Status Report 18 December 1995 - 7 January 1996 (Weeks 51, 52, and 01) ---------- Serge Savy 8-Jan-96 SXT operations during the past two weeks have been straightforward. We have carried out some special operations aimed at filament eruptions and the quiet corona. The next major joint observational campaign will be with the recently launched (7-Jan) Flare Genesis balloon flight over the next two weeks. SOLAR ACTIVITY The Sun was quiet during most of the last three weeks with no major flares. On 3 January the level of activity increased and many B-class flares occurred, and one C1 flare at 17:10 3-Jan-96 UT. This was just before the beginning of the first KSC telemetry after the holiday and we do not know whether Yohkoh observed the C1 flare. SXT INSTRUMENT STATUS The SXT instrument has continued to work well. There were no significant SXT errors during the last three weeks. 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 51: 8 KSC passes were lost due to conflicts with ASCA. Week 52: 4 and 2 KSC passes were lost due to conflicts with ASCA and SFU, respectively. Week 01: 2 KSC passes were lost due to conflicts with ASCA. CAMPAIGNS There have been no official SXT campaigns during the past two weeks but some special observations were carried out, specifically long-duration PFI exposures of the quiet corona near disk center. The FlareGenesis balloon flight from the Antarctic will be our next major effort. It was successfully launched about 24 hours prior to the time of writing, but alas suffered the loss of its high-gain antenna during the process. Yohkoh is in good e-mail contact with the group at McMurdo via Dave Rust. See http://sd-www.jhuapl.edu/FlareGenesis/flare.html for details. For the next couple of days there will be active regions on the disk, with the quite hot AR7938 just at the limb. SCIENCE In addition to the Cadavid seminar mentioned below, we have also had Bernie Jackson (UCSD) visiting during the first week of January. He is very happy about the situation with respect to the comparison of Yohkoh synoptic maps with IPS synoptic maps from Toyokawa (M. Kojima et al.). Bernie and Paul Hick have written better software - essentially a 3-D reconstruction of the corona - that makes a much cleaner comparison between the two data sets, and seems to confirm quite clearly the active-region signature in the solar wind. Graduate students in the Master's programs of various Japanese universities have thesis deadlines in January and are putting in long hours. SEMINARS There was a regular Yohkoh seminar on December 20. The speaker was Christina Cadavid (California State University Northridge) "On the Multifractal Distribution of Solar Magnetic Fields". PERSONNEL Gary Linford arrived on 4 January for a one-month stay, and Bernie Jackson for about a week. Week 51 Tohbans: SSOC: S. Tanuma, T. Yokoyama KSC: S. Morita, Y. Iizuka SXT Chief Observer: S. Savy SXT Systems and Data Engineer: Week 52 Tohbans: SSOC: S. Masuda KSC: S. Morita, Y. Iizuka SXT Chief Observer: S. Savy SXT Systems and Data Engineer: Week 01 Tohbans: SSOC: T. Kosugi, S. Savy KSC: J. Sato SXT Chief Observer: S. Savy, H. Hudson SXT Systems and Data Engineer: G. Linford