SXT Status Report May 29 - June 11, 2000 (Weeks 23-24) N. Nitta, H. Hudson SUMMARY Activity was moderate to high, with X-class flares; we co-observed these with La Palma observers and with TRACE. SXT has had no technical problems. SOLAR ACTIVITY NOAA active region 9026, on central meridian about June 7, produced two X-class flares on the 6th and one on the 7th. The flares on the 6th left a beautiful bright cusp reminiscent of the one studied by Yokoyama et al.; this was picked up by APOD (the Astronomical Picture of the Day) Web site even before we had a chance to write a nugget! The spot group attained an area of 910 millionths. The Yohkoh observations of the first two events (the 6th) were poor, on account of day/night and SAA interference. For the event on the 7th we got good material, but pre-flare observations are skimpy for the same reasons. The flare of the 7th, X1.2, was not obviously eruptive but did have a halo CME - so it must have been - and type II and IV bursts, the latter also suggesting eruption. But the question of _how_ it erupted seems interesting, as described in the the June 9 science nugget. This spate of activity took our minds off trans-equatorial loops, but Farnik's visit led to more discussion of these fascinating structures (see the nugget for June 2, which contains a cumulative listing of 8 of our previous pieces on this subject. Time for a review paper! OBSERVING CAMPAIGNS No official coordinations, but we believe quite profitable joint observations on AR9026. 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 No particular problems. Due to command errors, normal pointing for Yohkoh was mis-defined for two days. Special operations were carried out on May 30 and May 31 in preparation for the possible observation by HXT of the Crab Nebula, during its transit 1.2 degrees from the Sun on June 14. T. Kosugi circulated a memo on risk assessment for this unusual operation. TELEMETRY DOWNLINKS Week Wallops Santiago Goldstone Canberra Madrid Japan 22 27 0 0 2 0 28 23 27 0 1 0 7 21 24 31 0 3 0 11 23 25 31 0 5 0 4 30 SXT OBSERVING SEQUENCE TABLES ------------------------------------------------- JST Day UT Date & Time Pass Table ID ================================================= Tuesday AM 29-MAY-00 21:38 4 000529 P4 ARS1 DARK* Wednesday AM 30-MAY-00 14:59 1 000530 P1 ARS1 DIF* Wednesday AM 30-MAY-00 21:47 5 000530 P4 ARS1 STD* Thursday AM 31-MAY-00 15:05 1 000531 P4 ARS1 FRFFI* Thursday AM 31-MAY-00 20:13 4 000531 P4 ARS1 QRFFI* Friday AM 1-JUN-00 20:22 4 000601 P4 ARS1 STD* Sunday AM 3-JUN-00 17:14 3 000602 P4 ARS1 STD* Monday PM 05-JUN-00 14:07 2 000605 P2 ARS2 STD Tuesday AM 05-JUN-00 17:32 4 000605 P4 ARS1 STD Wednesday AM 06-JUN-00 17:40 4 000606 P4 ARS1 DIF Thursday AM 07-JUN-00 17:59 4 000607 P4 ARS1 DARK Thursday PM 08-JUN-00 11:10 1 000608 P1 ARS2 PFIDOM Friday AM 08-JUN-00 16:15 4 000608 P4 ARS1 STD Saturday AM 09-JUN-00 16:23 4 000609 P4 ARS1 STD Sunday AM 10-JUN-00 16:32 4 000610 P4 ARS1 STD ================================================= Data reformatting is complete through 27-May-00 (week 00_22). SCIENCE Seminar: S. Hirose (SUT), "MHD Simulation of Dark Filament Eruption and Arcade Flaring". Science Nuggets 2-Jun-00: "Recent observations of trans-equatorial interconnecting loops" Inspired by Farnik's visit, one of the key questions being asked is the nature of the connectivity of these structures. It is hard for SXT images to be definitive, since many of the TILs straggle diffusively into weak mixed-polarity regions. The nugget notes short time-scale variability. 9-Jun-00: "X-class flares illuminate a coronal problem" The problem is that the June 7th X-flare, with its coronal disturbances, somehow managed not to affect the beatiful cusp left by the previous day's flares; it just kept on being beautiful and did not even wiggle. Lower-lying EIT loops did display a slow reaction, however. 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 . PERSONNEL H. Hudson arrived; F. Farnik departed; N. Nitta departed. TOHBANS (spacecraft operators) Tohbans for week 23 SSOC: M. Sawa, D. Suzuki KSC: H. Tonooka , Y. Katsukawa SXT_CO: N. V. Nitta SXT_SW: - Tohbans for week 24 SSOC: H. Hara KSC: H. Tonooka , Y. Katsukawa, Y. Matsumoto SXT_CO: N. V. Nitta, H. S. Hudson SXT_SW: -