SXT Status Report 18 Nov. 1997 - 1 Dec. 1997 (Weeks 47-48) D. McKenzie, N. Nitta, H. Hudson, S. Savy, M. Weber SUMMARY Solar activity remained at a high level during this period, with yet more spectacular M and X flares. SXT has operated well with no special problems related to the high activity. There were no formal campaigns. SOLAR ACTIVITY The large flares during this period were interesting and also interestingly different from the ones of the previous reporting period. From the SXT point of view, the "Thanksgiving flare" of Nov. 27 was the most energetic. It showed impulsive hard X-ray bursts and was compact in soft X-rays. Its spectacular ejections were in patterns reminiscent of other ejections (large-scale and small-scale) from the region (NOAA 8113). The sunspot area in this region had reached 610 millionths by November 28. See a couple of places further along in this report for more comments on this particular flare. It was well observed because flare mode came early, thanks to a precursor small event. These days we are getting frequent alert messages from Big Bear and from Pat Mcintosh - often surprisingly accurate. Flares clearly don't just blow out of the photosphere, as Ambartsumian speculated - there really is some period of energy build-up that allows these short-term predictions to work so well. SXT INSTRUMENT STATUS AND CALIBRATION ACTIVITIES SXT continues to operate well. There was no repetition of the ground-based software problems previously reported. Several DSN passes and one KSC pass were lost because of the launch of TRMM - the launch was inconveniently scheduled for Tanegashima, apparently into an orbit that pretty much matched the trajectory of Yohkoh. Data archiving is complete through Week 45 (ending Nov. 10, 1997). With the flares this week, our quick-look analysis leads us to believe that the "new" flare table, emphasizing ejections, is working pretty well. The Web report shows that the November 27 flare ejections were visible on many consecutive low-resolution images, which is the desirable situation. There is also material enough to make a temperature measurement from HR observations in Al12 and AlMg fixed exposures. This will be difficult because of the rapid motions, but an estimate should be possible. WEB-BASED SCIENCE REPORTS The scheme of weekly reporting by the SXT Chief Observer on Web pages has continued. The current report is now at ftp://isass0.solar.isas.ac.jp/pub/sxt_co/SXTweekly.html and deals with the X2.9 eruptive flare of Nov. 27 (Thanksgiving Day!). In the near term, at least, this URL will be a fixed point of reference for these "science nuggets". Check this SXTweekly.html out please - we see a sideways eruption moving at about 330 km/s (projected), with a clear and interesting evolution of magnetic loops. Is this apparently horizontal motion consistent with the CSHKP model? As the Web page shows, the motion is observable during the prominent impulsive spikes, but would have had to have started BEFORE them if extrapolated back to the photosphere - a small-scale counterpart to the Harrison timing relationship often cited for CMEs. On the other hand, there was an earlier lower level of activity that makes this relationship ambiguous. Does this fit into the complex pattern of flares and ejecta described by Shibata et al (1995; ApJ 451L, 83)? Previous reports in this series are at the following URLs: ftp://isass0.solar.isas.ac.jp/pub/sxt_co/971024.html dimming ftp://isass0.solar.isas.ac.jp/pub/sxt_co/971031.html EIT Calroc ftp://isass0.solar.isas.ac.jp/pub/sxt_co/971107.html Nov 6 flare ftp://isass0.solar.isas.ac.jp/pub/sxt_co/971114.html Nov 14 LDE ftp://isass0.solar.isas.ac.jp/pub/sxt_co/971121.html Movies of ejecta! ftp://isass0.solar.isas.ac.jp/pub/sxt_co/971128.html X2.9 ejective flare The SXT_CO's have figured out how to run Sam Freeland's easy movie software, so the more recent "nuggets" have nice JPEG movies showing dynamic things. Soon: full stero sound effects! Again, please let us know if anybody else finds these pages to be interesting. Whereas it's child's play to make a simple Web page, such as 971031.html, it took Nitta and Hudson perhaps a full analysis-day to do 971128.html. The problem is that these things are so doggone interesting you want to drop whatever you're supposed to be doing and investigate! PASS CONFLICTS AT KSC Week 47, six passes lost to HALCA. Week 48, three passes lost to HALCA, one to TRMM. CAMPAIGNS There were no formal campaigns during these two weeks. We have attempted to look out for jets in response to Shimojo's request. For Yohkoh target planning, the SXT weekly observing plan is available on the Web at http://www.space.lockheed.com/SXT/html2/First_Light.html or with "finger campaign@isass0.solar.isas.ac.jp | more". See http://sohowww.nascom.nasa.gov/operations/targets/today for SoHO target planning. VISITORS AND PERSONNEL McKenzie and Nitta departed; Weber arrived. Ohyama has taken an ISAS position and has moved into D-toh on a regular basis. The D-toh Americans went out for Thanksgiving turkey on an action-filled Nov. 27. British and Japanese colleagues mostly had chimichangas. SEMINARS There were Yohkoh seminar talks on Thursday, Nov. 27: H.S. Hudson: "How to coalign CDS with the world" A.C. Sterling: "3D Structures of active regions - in one dimension" Te. Watanabe: "Recent active region diagnostic results via Yohkoh" These were all inspired, more or less, by the Paris workshop. Hudson's talk was a review of a recent paper by Thompson and Carter on CDS coalignment, interest in this subject being inspired by the horror stories from the Paris workshop about the primitive level of coalignment practice in SOHO data analysis. Perhaps part of the problem is that SOHO is only a couple of years old, and accurate coalignment requires that all pieces of the puzzle be assembled; however, one has to worry now about SOLAR-B which will have much more demanding ambitions for coalignment (factor of 100 better than Yohkoh; factor of 10 better than SOHO?). TOHBANS Tohbans for Week 47: SSOC : Watari KSC : Ichimoto & Sasaki SXT_CO: N. Nitta SXT_SW: G. Slater Tohbans for Week 48: SSOC : UeNo & Hudson KSC : Ichimoto & Suematsu SXT_CO: N. Nitta SXT_SW: -