SXT Status Report 11-24 October 1999 (Weeks 42-43) L. Fletcher, H. Hudson, D. McKenzie SUMMARY Activity increased to more interesting levels, with a couple of outstanding flares. Yohkoh SXT took part in two joint observing campaigns, to observe signatures of emerging flux and to make images of flares with high temporal and spatial resolution. SOLAR ACTIVITY Solar activity increased, the background hovering at the GOES C level for most of the 2-week period. An X1.8 flare with fairly short duration occurred while Yohkoh was in SAA (14-OCT-99 08:54 UT). An M1.7 flare occurred on 20-OCT, while SXT was in PFI-dominant mode and fixed pointing for JOP 113 -- SXT acquired data in the preflare and impulsive phases of this and several smaller (C-class) flares. OBSERVING CAMPAIGNS Yohkoh/SXT supported a campaign led by Brigitte Schmieder to observe the signatures of emerging flux and arch filament systems, from 11-oct to 17-oct. Yohkoh/SXT participated in JOP 113 in collaboration with TRACE and several ground-based observatories from 19-October onward. This campaign is intended to make images of flares with high temporal and spatial resolution. As of the time of this writing, one M-class and several C-class flares have been observed as part of this ongoing JOP. 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 A normal pointing update was made on 14-oct. On 18-oct the flare trigger threshold was brought back down to approximately GOES C2-C3, which was the level used for the first 8 years of the mission. This was done to give us more flare data for JOP 113; we may raise the threshold again after the JOP has completed. On 8-oct the star tracker did not watch Canopus from 04:00 UT to 21:00 UT, due to incorrect parameters being used in the STT timer setting. The parameters for 28-sep were used, when the parameters for 5-oct should have been used. This was a human error by an SSOC Tohban, not a hardware error; however the spacecraft rolled by about one degree from the nominal value during this 17 hour period. On 21-Oct an anomalously high level was found in a NaBan straylight monitor image; this is believed to be due to CCD bleed from the serial registers at the bottom of the CCD, and NOT due to a new entrance filter rupture. Subsequent straylight monitor images in NaBan and WdBan filters show normal signal levels. The flush count of the NaBan images was increased from 4/1/1 to F/2/3 to see if this reduces the CCD bleed. SXT OBSERVING SEQUENCE TABLES ------------------------------------------------------------- UT Date & Time Pass Table ID ============================================================= 11-Oct-99 07:07 1 991011 P1 ARS1 STD 12-Oct-99 09:02 2 991012 P2 ARS1 DARKCAL 13-Oct-99 05:51 1 991013 P1 ARS0 DIFF+IL 13-Oct-99 10:59 4 991013 P4 ARS1 STD 14-Oct-99 09:29 3 991014 P3 ARS1 STD 15-Oct-99 08:00 3 991014 P3 ARS1 STD 16-Oct-99 04:48 1 991015 P1 ARS1 STD 18-OCT-99 03:33 1 991018 P1 ARS1 DARKCAL 18-OCT-99 08:40 4 991018 P4 ARS1 DIFF 19-OCT-99 07:10 3 991019 P3 FLARE SPEC 20-OCT-99 03:58 1 991020 P1 FLARE SPEC (PFI-dominant) 20-OCT-99 09:07 4 991020 P4 FLARE SPEC (back to FFI-dom) 21-OCT-99 04:11 2 991021 P2 FLARE SPEC 22-OCT-99 04:25 3 991022 P3 FLARE SPEC 23-OCT-99 01:14 1 991022 P1 ARS1 STD ============================================================= SCIENCE The following weekly science nuggets were produced. 15-Oct-99: "A Fat Filament Flares Followed by Fine Loops and a Phoenix" 22-Oct-99: Early success for JOP 113 vs. Murphy's Law 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 2 seminars, on Thursday October 14th: 'A Sharper Tool than the Aly Conjecture' - Hugh Hudson (SPRC) and 'Balloon Project for Hard X-ray Flare Observations' - K. Kobayashi (Tokyo U.) YOHKOH OPERATIONS ISSUES 1.) Keep an eye on the NaBan straylight monitor images (FFI#1, entry 2-2, Op/NB Dark QC1N) to see if the saturation bleed from the bottom of the CCD goes away after 25-oct, when the flush was increased from 4/1/1 to F/2/3. 2.) It's been three months since our last bakeout. 3.) Mercury transit is 15-Nov; Leonids meteor shower is 18-Nov. Soon! PERSONNEL Lyndsay Fletcher arrived from Palo Alto; Phil Shirts returned to Palo Alto; Hugh Hudson travelled to GSFC for the HESSI workshop. TOHBANS (spacecraft operators) Tohbans for week 42 SSOC: K. Kobayashi, T. Sakao KSC: D. Suzuki, Y. Katsukawa SXT_CO: L. Fletcher, H. Hudson SXT_SW: P. Shirts Tohbans for week 43 SSOC: R. Kano, N. Shinohara KSC: Y. Katsukawa, M. Shimojo SXT_CO: L. Fletcher, D. McKenzie SXT_SW: P. Shirts