SXT Status Report 25 February 1997 to 14 March 1997 (Weeks 9-11) T. Metcalf, J. Lemen SUMMARY SXT continued to operate well, and activity was generally low. SOLAR ACTIVITY Activity was low throughout weeks 9 through 11, with the exception of a few small flares early in week 9 and late in week 10. New cycle active region 8019 passed from the East limb to near central meridian during the week at a very high latitude. AR 8020 produced a B-level LDE which lasted several hours. An accompanying CME was reportedly observed in the LASCO C3 images. There was a solar eclipse on 1997 March 09. For Yohkoh, this was not one of our better eclipse observing opportunities. The eclipse could be only seen in one orbit, and it was a rather shallow partial eclipse at that (less than 30%). A special SXT table was uploaded to take high cadence images in AlMg with quarter resolution for a period of 22 mins centered on 01:05 UT (time of maximum eclipse). As is typical, special commands were included in the OP command load to make sure that the Sun sensor and attitude control systems were not confused by the lunar obstruction. Since the eclipse occurred on a spacecraft holiday (Sunday), the data was scheduled to be telemetered to a DSN station. We are awaiting the arrival and reformatting of the data to review the results. SXT INSTRUMENT STATUS SXT continues to perform well. The only thing that stops SXT is the occasional SEU (single electron upset). We had two during the past week. This usually happens when the orbit apogee occurs during the passage through the SAA. Since AR8019 was at a high latitude, the standard SXT patrol image did not cover the region. We moved the patrol image to the north by about 275" to include the region in the patrol image. CO's will have to monitor the location of the patrol image as more new cycle regions at high latitudes appear. SXT CALIBRATION ACTIVITIES In week 10 we got several new terminators, including the first AL12 since September. A new version of the op_first_guess software was installed on 26 February which promises to make the terminator scheduling and acquisition more efficient. During this period 9 terminators have been put on line. PASS CONFLICTS Week 9: 1 pass cancelled for ASCA, 4 for AKEBONO, and 4 for HALCA Week 10: 1 pass cancelled for ASCA, 2 for AKEBONO, and 1 for HALCA 2 passes cancelled due to planned power outage at KSC Week 11: 2 passes cancelled for ASCA, 3 for AKEBONO CAMPAIGNS There was one campaign during week 9. On Monday Feb 24 and Thursday Feb 27, SXT observed AR8019 in ARS2 mode in conjunction with CDS on SOHO. The purpose was to observe filling factors (PI: Jim Klimchuk). An informal campaign involving SOHO CDS, SOHO EIT, and Sac Peak was conducted 7-10 March under direction of Peter Young and Andrzej Fludra. The objective was to observe an active region at the limb. For Yohkoh target planning, the SXT weekly observing plan is available on the Web at http://www.space.lockheed.com/SXT/html2/First_Light.html or with "finger campaign@isass0.solar.isas.ac.jp | more" . See http://sohowww.nascom.nasa.gov/operations/targets/today" for SoHO target planning. VISITORS AND PERSONNEL Greg Slater departed (28-Feb) to observe the solar eclipse in Mongolia and Tom Metcalf (7-Mar) and James Lemen (14-Mar) returned to California. We were paid a visit by Dr Hurburt Gursky (director of the E. O. Hulbert Center, NRL). An enjoyable afternoon was spent with Dr Gursky reviewing Yohkoh data and results. SEMINARS There was a double Yohkoh seminar: T. Metcalf (LPARL), "Magnetic Free Energy in Active Regions: the Vector Magnetogram Story" and Ta. Watanabe (Ibaraki), "Soft X-ray, H-alpha and White Light Observations of an Eruptive Prominence of 20 April 1992". Week 9 Tohbans SSOC: K. Nakakubo, T. Kobiki & K. Akita KSC: H. Sekiguchi & Y. Nakagawa SXT CO: T. Metcalf & J. Lemen Software: G. Slater Week 10 Tohbans SSOC: M. Irie & T. Shimizu KSC: Y. Nakagawa & K. Shibasaki SXT CO: T. Metcalf & J. Lemen Software: (J. Lemen) Week 11 Tohbans SSOC: Y. Nishino & K. Ichimoto KSC: K. Shibasaki & Y. Nakagawa(-13) SXT CO: J. Lemen & S. Savy Software: (J. Lemen) QUOTATION "They had absolutely nothing. But they were willing to risk it all." (from the film, The Commitments, 1991).