SXT Status Report Start of Millenium to Jan. 17, 2000 (Weeks 01-03) H.S. Hudson, D. McKenzie SUMMARY Yohkoh returned from its Y2K absence with flags flying - no problems in space whatsoever. The Sun had been quiet over the long New Year's holiday, but higher activity resumed in time for the Flare Genesis telescope's flight around the South Pole. SOLAR ACTIVITY At the end of the millenium, a huge coronal hole was nearing disk center. Bearing in mind the "disappearing solar wind", a gullible Chief Observer actually wondered (see the science nugget for Dec. 31) whether or not this equatorial coronal hole would again turn off the solar wind --- it did not. There have been 5 M-class flares thus far this year. OBSERVING CAMPAIGNS The Flare Genesis telescope was launched, and at the time of writing is observing NOAA AR 8824, apparently completely successfully. Yohkoh and many observatories around the world - and remote from it - are concentrating on its targets. The first series of AR observations was probably not very productive in terms of major flares, but the active region (NOAA 8821) was not without microflare activity and (according to our images) had a rather curious sigmoidicity. Please see our webpages for more details about campaigns past and future: http://isass1.solar.isas.ac.jp/sxt_co/sxt_catalog.html http://isass1.solar.isas.ac.jp/sxt_co/sxt_future.html SXT INSTRUMENT STATUS AND CALIBRATION ACTIVITIES During New Year's holidays, Yohkoh undergoes severe thermal stresses because of the lack of active heater control. Again the spacecraft and the instruments appear to have survived well. Pointing remains stable and the data look, as usual, great. In spite of much preparation, Y2K bugs struck pretty hard in many trivial directions, all in the areas of data-transfer and data-preparation software. Recovery has been swift on all sides, but we keep discovering little things that go wrong. There have been only minimal impediments to normal operations. SXT OBSERVING SEQUENCE TABLES ------------------------------------------------------------- UT Date & Time Pass Table ID ============================================================= Wednesday AM 04-JAN-00 17:18 3 000104 P3 ARS1 DKCAL Friday AM 06-JAN-00 17:43 3 000106 P3 ARS1 DKCAL Friday AM 7-Jan-00 12:47 1 000107 P1 ARS1 DIFF Saturday AM 8-Jan-00 14:41 2 000108 P2 ARS0 FG Monday PM 10-Jan-00 13:23 2 000110 P1 ARS2 FG Tuesday PM 11-Jan-00 13:35 2 000111 P2 ARS2 FG Wednesday PM 12-Jan-00 10:24 1 000112 P1 ARS2 FG Thursday PM 13-Jan-00 12:17 2 000113 P2 ARS2 DKCAL Friday PM 14-Jan-00 09:07 1 000114 P1 ARS2 FG/DIFF Friday PM 14-Jan-00 12:29 3 000114 P1 ARS1 FG/DIFF Saturday PM 15-Jan-00 10:59 2 000115 P2 ARS0 FG ============================================================ SCIENCE December 31: "The solar wind disappears!" - A Yohkoh follow-up on the AGU press release on the remarkably weak solar wind during the interval May 10-12, 1999; during this period the Earth's bow shock expanded hugely and the solar-wind critical point approached one A.U.! Guest co-authors J. Luhmann and D. Larsen. Yohkoh sees things that lead us to believe that another such "disappearing wind" interval may well happen Jan. 4-6. January 7: "Yohkoh returns from hibernation" - just basically reporting on the new data, and retracting the rash predictions the previous nugget offered. There is still a problem: if the solar-wind ram pressure at 1 AU can drop by almost two decades for a couple of days, what on Earth on the Sun could have caused this? January 14: "Exceptionally hard X-rays and an eruption" - an M4.5 flare on 28-Dec-99 had an energy spectrum so hard, it's hard to believe and harder to understand. Heartily hard, even. The full list of nuggets is kept on http://isass1.solar.isas.ac.jp/sxt_co/index.html , and the current week's nugget also normally resides on http://isass1.solar.isas.ac.jp/sxt_co/SXTweekly.html . SEMINARS January 13: H. Hudson (SPRC), "The Origins of CMEs". Actually the preview of a seminar presentation that touts SXT's ability to see things in the low corona at the times of CME launches - leaning heavily on the work of ISAS research by Akiyama, Hudson, Khan, Nitta, McKenzie, and Sterling in particular, and with a nod or two to Freeland, Klimchuk, and Ohyama. PERSONNEL D. McKenzie arrived Jan. 16. TOHBANS (spacecraft operators) Tohbans for week 01 SSOC: - KSC: - SXT_CO: H.S. Hudson SXT_SW: - Tohbans for week 02 SSOC: H. Hara, M. Nishio KSC: Te. Watanabe, M. Shimojo SXT_CO: H. Hudson SXT_SW: - Tohbans for week 03 SSOC: K. Nakakubo(ex14,17), K. Ichimoto(ex17) KSC: M. Shimojo, T. Yamasaki SXT_CO: H. Hudson SXT_SW: -