SXT Status Report Jan. 19, 1998 - Jan. 31, 1998 (Weeks 4-5) H. Hudson, L. Acton, S. Savy SUMMARY Yohkoh and SXT continue to operate well. Solar activity diminished during this period but there were some flares. The high point of the interval was the successful flight of the XDT rocket from the Kagoshima Space Center, the topic for week 5's Web report at ftp://isass0.solar.isas.ac.jp/pub/sxt_co/SXTweekly.html. THE XDT ROCKET The following is excerpted from the BCS weekly status report: the XDT flight was almost a complete success, and 14 "Doppler pair" images were obtained via telemetry. There may have been a problem at the end of the flight in deploying the parachute, so that recovery of the payload from the sea (including a memory module with 2/3 of the data) appears problematic right now. A preliminary image has appeared in the newspapers, and it looks very good. SOLAR ACTIVITY There were ~7 C-class flares during this interval, plus an M-class, but activity could only be described as tepid. The McIntosh "solar status" reports were helpful and insightful. The background GOES level dropped below B at the end of week 5, with little sign of new regions, so we have been in a lower activity level for a while. SXT INSTRUMENT STATUS AND CALIBRATION ACTIVITIES The Wallops scheduling of NASA telemetry support is now going smoothly. We are still working on software to restore automation to the level we had during the DSN scheduling era. Yohkoh is grateful for prompt assistance from Rick Jones at Wallops in getting extra contact passes on Jan. 31, to support the XDT rocket - we were able to "double dump" the key data to be sure that we got them, and also to get some key pre-flare observations. L. Acton has spent most of his visit efficiently employed on straightening out the stray-light software and database situation. J.-P. Wuelser has also been involved in redefining the ATT database from which all of the standard pointing information is derived. We are getting closer to the new movie. Data archiving is complete through Week 50 (ending Dec. 13, 1997). WEB-BASED SCIENCE REPORTS The scheme of weekly reporting by the SXT Chief Observer on Web pages has continued. The current "science nugget" is normally at ftp://isass0.solar.isas.ac.jp/pub/sxt_co/SXTweekly.html which links to this report and other pages, the previous science nuggets reported by SXT chief observers. See index.html for the following list: 971024.html dimming 971107.html Nov 6 flare 971114.html Nov 14 LDE 971121.html Movies of ejecta! 971128.html X2.9 ejective flare 971205.html Solar cycle 971215.html Amazing arcade 971221.html AR development 971228.html Interconnection 980110.html Global time constant? 970117.html Contrasting emergence 970124.html Data request from Ooty 970131.html XDT rocket flies! PASS CONFLICTS AT KSC (Akebono, HALCA, ASCA) Week 4: Four passes lost to HALCA, one to Akebono, and five to 20-m antenna maintenance work. Week 5: One pass lost to HALCA. CAMPAIGNS Yohkoh conducted special observations in support of N. Gopalswamy's VLA run. There were good observations but disappointing - we predicted that the southern polar crown would "blow", and it did, but unfortunately outside the VLA window. SXT consequently was also not looking at it with PFIs. The main special activity, culminating in a successful flight on Jan. 31, was the XDT rocket (team led by S. Tsuneta). SXT obtained supporting observations both of the principal target and also of a reference region of the quiet Sun, useful for atmospheric corrections to the rocket data. For details of campaign planning, see http://www.space.lockheed.com/SXT/html2/First_Light.html or do "finger campaign@isass0.solar.isas.ac.jp | more" from your Unix command line. See http://sohowww.nascom.nasa.gov/operations/targets/today for SoHO target planning. VISITORS AND PERSONNEL Visitor M. Sersen spent two weeks at ISAS and worked extensively on evidence for the involvement of complex magnetic polarities in arcade event formation. Not suprisingly he had an interesting and useful discussion with Prof. Uchida during his stay! L.W. Acton departed after a fruitful visit. SEMINARS A new seminar series started: Jan. 22: M. Sersen (U. Bratislava) "CSHKP Versus 'Quadrupole' Model of Eruptive Events" - probed a subject lies at the heart of one of our biggest unknowns: how does a CME or an eruptive flare start? Jan. 29: L.W. Acton (MSU) "Solar Irradiance and Telescope Design" - included a convincing demonstration that broad-band filter photometry for X-rays is greatly improved by the inclusion of a second channel! TOHBANS Tohbans for Week 4 SSOC : Y. Hanaoka, K. Yaji KSC : K. Hori & K. Kobayashi SXT_CO: H. Hudson SXT_SW: - Tohbans for Week 5 SSOC: S.Kubo & A.Shiozawa KSC : K. Hori & K. Kobayashi SXT_CO: H. Hudson SXT_SW: -