SXT Status Report January 5, 1999 through January 18, 1999 (Weeks 2-3) D. McKenzie, H. Hudson SUMMARY The New Year saw a sharp cessation of solar activity as region 8421 and its henchmen rotated past the NW limb. SXT worked well throughout this interval; we had no formal observing campaigns. SOLAR ACTIVITY Following the sharp decline around Jan. 8, activity rose again around Jan. 12 and we had several M-class flares. None of these seem to have been well-observed or interesting, or else the data are still migrating from DSN to ISAS. The transequatorial interconnecting loops continue to be interesting; at the time of this report we had two major regions, north and south, at almost the same heliolongitude. So, stay tuned for further interconnecting-loop comments. The regions are NOAA #'s 8439 and 8440, neither with very large spot area but extremely intense soft X-ray emission. OBSERVING CAMPAIGNS There were no formal coordinate campaign observations during the interval, but as usual we have tried to take our station based on TRACE maneuvers. SXT INSTRUMENT STATUS AND CALIBRATION ACTIVITIES We have had several false flare triggers and flare-mode data interruptions due to geomagnetic particles. These all appear to result from normal Yohkoh spacecraft functions, plus unusually complicated radiation patterns. Please see the more detailed commentary prepared for the weekly SXT report for week 3, accessible through the science nugget for this week (see http://www.solar.isas.ac.jp/sxt_co/990115.html ). SXT OBSERVING SEQUENCE TABLES ----------------------------------------------------------------- JST Day UT Time Pass Table ID ================================================================= 06-JAN-99 00:53 3 990105 P3 DARKCAL 06-JAN-99 20:02 1 990106 P1 ARS1 DIFF 06-JAN-93 23:27 1 990106 P3 ARS1 STD 07-JAN-93 20:18 2 990107 P2 ARS1 STD 08-JAN-93 20:34 2 990108 P2 ARS1 STD 10-JAN-99 19:24 2 990110 P2 ARS1 STD 11-JAN-99 19:41 2 990111 P2 ARS1 DARKCAL 12-JAN-99 18:14 2 990112 P2 ARS1 STD 13-JAN-99 16:48 1 990113 P1 ARS1 DIFF 13-JAN-99 21:56 4 990113 P4 ARS1 STD 14-JAN-99 17:04 2 990114 P2 ARS1 STD 15-JAN-99 17:20 2 990115 P2 ARS1 STD 16-JAN-99 15:54 2 990116 P2 ARS1 STD ===================================================== SCIENCE Science roared back into life at D-toh, following the New Year's break. Shimojo_san successfully presented his PhD research and immediately took a break! The WAVES experiment on WIND has been observing interplanetary II and III bursts, and we have been trying to help identify the solar origins of some of these. Week 3's science nugget deals with this issue (see the URLs given above or below). Other than the flares, some of the more interesting things SXT has been seeing have to do with coronal-hole configurations and with interconnecting loop structures. These provided the topic for the week 2 science nugget (see URL below). Please check out all or any of the recent weekly science nuggets embedded in the SXT operations reports: 1-Jan-98 A coronal microflare 8-Jan-98 Two coronal holes, one with a whorl 15-Jan-98 Apparent eruption near disk center The URL's for these and for the full list of science nuggets can be found on http://www.solar.isas.ac.jp/sxt_co/index.html, and the current week's nugget is also always kept on http://www.solar.isas.ac.jp/sxt_co/SXTweekly.html. SEMINARS No Yohkoh ISAS seminars during this period. OPERATIONS ISSUES We now have plenty of flares, and we are seeing the operation of the Yohkoh flare trigger in greater detail than any time for the last few years. So, we are studying its behavior with an eye towards re-optimizing if need be. VISITORS AND PERSONNEL No changes in SXT staff; no visitors except for tohbans. TOHBANS (spacecraft operators) Tohbans for week 02 SSOC : J. Sato & H. Hara KSC : Y. Iizuka & Y. Kato SXT_CO: H. Hudson => D. McKenzie SXT_SW: - Tohbans for week 03 SSOC : K. Fujiki, Y. Saito KSC : H. Ishizaki, Y. Iizuka SXT_CO: D. McKenzie SXT_SW: -