SXT Status Report December 14, 1999 to End of Millenium (Weeks 51-53) N.V. Nitta, H.S. Hudson SUMMARY Activity was not so high, with only 8 M flares. There were no problems. SOLAR ACTIVITY Well, 1999 turned out to be a dud from the point of view of X-class flares; only four all year so far as I'm aware. Ed Cliver pointed out that this may have something to do with the "Gnevyshev Gap," a known tendency for geomagnetic activity to diminish temporarily at solar maximum. It is also well-known anecdotally that proton flares and other major solar activity also favor the rising and decaying phases of a solar maximum. But, could we consider 1999 to be the year of maximum? It does not sound quite right. The sunspot area of AR 8806 exceeded 1,000 near its central meridian passage. There is currently (Dec. 30) what appears to be a huge equatorial coronal hole. OBSERVING CAMPAIGNS The Flare Genesis telescope is still poised at its launch site in the Antarctic at the time of writing. We have been following activity and writing routine recommendations regarding target selection, but of course we won't see quasi-real-time data again until Jan. 4 because of the long New Year's operations hiatus for Yohkoh. Meanwhile, TRACE is in its eclipse season, and all is calm throughout the solar world. 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 Normal pointing updates were done Dec. 13 and Dec. 27. The new software and procedures seem to work fine. In between these dates an unusually large drift took place, giving us a view of the stray-light pointing dependence at least in the direction of excursion to the north. The CCD bakeout reported in the last status report in fact resulted in diminished dark current, albeit not much, so we will plan to continue doing these routinely. The next quarterly opportunity would be in mid-March. We have been running new flare-mode sequences designed by D. McKenzie to trick the AEC function into providing optimally overexposed flare images. For the larger fields of view these are essential if we are to study the faint but interesting coronal structures associated with flaring. Please help us to assess these new data! Final data reformatting is complete through 18 December 1999, and the video movie is complete to that date (thanks, Greg Slater!). SXT OBSERVING SEQUENCE TABLES ------------------------------------------------------------- UT Date & Time Pass Table ID ============================================================= Monday AM 13-DEC-99 00:35 1 991213 P1 DIFF Monday AM 13-DEC-99 03:58 3 991213 P3 DARKCAL Tuesday AM 14-DEC-99 04:11 5 991214 P3 STD Wednesday AM 15-DEC-99 04:23 3 991215 P3 STD Thursday AM 16-DEC-99 04:36 4 991216 P4 STD Saturday AM 18-DEC-99 01:36 3 991218 P3 ARS1 STD Monday PM 20-DEC-99 03:44 4 991220 P4 ARS1 DARK Tuesday AM 21-DEC-99 00:31 3 991220 P3 ARS1 DIFF Wednesday AM 21-DEC-99 21:07 1 991221 P1 ARS1 FG Thursday AM 22-DEC-99 21:30 2* 991222 P1 ARS2 FG Thursday AM 23-DEC-99 00:56 4 991222 P4 ARS2 FG Friday AM 23-DEC-99 23:26 3 991223 P3 ARS1 FG Saturday AM 24-DEC-99 23:38 3 991224 P3 ARS1 STD Monday AM 26-DEC-99 18:55 1 991226 P1 ARS1 DIFF Monday AM 27-DEC-99 00:03 4 991226 P4 ARS1 DARK Tuesday AM 27-DEC-99 17:26 1 991227 P1 ARS1 FG Wednesday AM 28-DEC-99 21:02 3 991228 P3 ARS1 FG Thursday AM 29-DEC-99 19:31 3 991229 P3 ARS1 STD ============================================================ SCIENCE The weekly science nuggets emphasize global and interplanetary issues: December 17: "CME on 17 August 1999." Introduces the concept of the 'tired sigmoid' in the study of an event from the Whole Sun Month (3) interval, or just before. This event shows wide-spread effects, which we (ie, SXT) is getting more adept at observing. December 24: "Filament eruption and halo CME on 9 June 1998." This continues discussion of the involvement of large-scale structures (filament channels?) in CME formation, rather than a single active region (which often assumes an S-like shape). 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. 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 None. There were many holidays. PERSONNEL Hugh Hudson left and returned. Nariaki Nitta and Greg Slater returned and left. Jingxiu Wang visited and worked with NVN on large-scale CME antecedents. TOHBANS (spacecraft operators) Tohbans for week 51 SSOC: S. Tsuneta, S. Hata KSC: S. Kumagai, T. Kobayashi SXT_CO: H.S. Hudson, N.V. Nitta SXT_ST: G. Slater Tohbans for week 52 SSOC: R. Kano, (Te. Watanabe) KSC: T. Kobayashi, K. Ichimoto SXT_CO: N.V. Nitta SXT_ST: G. Slater Tohbans for week 53 SSOC: Te. Watanabe KSC: T. Kobayashi, K.Ichimoto SXT_CO: N. Nitta, H. Hudson SXT_ST: G. Slater