SXT Status Report 26 Feb. - 18 Mar. 1995 (Weeks 9-11) --------- Mark A. Weber 20-Mar-1995 SOLAR ACTIVITY The quiet side of the Sun has been in view for most of the past three weeks, so activity has been generally low. GOES data shows B-level background with some sporadic C-level activity. There have been no M-class events despite some threatening attempts on the part of the Sun. COORDINATED CAMPAIGNS There were no coordinated campaigns in weeks 9 or 10 (26 Feb. - 11 Mar.). (1.) Filament hunt: The SXT Chief Observer discussed with K. Reardon the possibility of assisting with filament observation during this passage of the quiet side of the Sun. The purpose of this campaign is to observe filament channels and possibly catch eruptions with SXT in a configuration for good resolution. This observation would have been done during week 11; however, due to a data gap of a couple of days, the CO decided to not risk overexposing the SXT CCD camera. (See SXT INTRUMENT STATUS, item 2.) Since there will be plenty of opportunities to make these observations, the cancellation is of no great concern. (2.) VLA bright points: SXT assisted N. Nitta with an attempt to observe coronal bright points. Nitta san acquired the use of the VLA for solar observing from 15:00 Mar. 17 to 00:00 Mar. 18. Our intent was to observe flaring bright points with SXT and in long wavelengths with the VLA. In a contrary fashion, the Sun produced a bright area which snagged the SXT observing region away from the area we agreed upon with Nitta san. We are currently awaiting the rest of the data downlinked to a DSN station to see if SXT found its way back to the chosen area. SXT CALIBRATION (1.) CCD "bakeout": SXT Chief Observer L. Acton ran a CCD bakeout from Mar. 1 to Mar. 3 with the assistance of M. Weber. These are commonly done every four months or so, but it had been closer to six months since the previous bakeout. We are happy to report that the bakeout proceeded quite smoothly, and the CCD returned easily to its standard operating temperature. (2.) Straylight- terminator offpointing campaign: As part of the calibration process for the straylight impinging upon the CCD camera, it is important to collect a database of "terminator" images. L. Acton has shown that the straylight signal is dependent upon the sun center pointing of the SXT, so the terminator (or SFT) database should include sun center pointings commensurate to the sun center pointings of the larger SFR database. Acton has initiated a campaign to acquire, in a deliberate way, a comprehensive set of SFT data. H. Hudson and M. Weber are currently assisting him with producing software tools to make this a relatively painless procedure for COs and tohbans alike. SXT INSTRUMENT STATUS In general, SXT continues to function smoothly, with a couple of notable exceptions. (1.) On Mar. 7, during a KSC pass, an error was generated when the mainframe computer detected a mismatch between the SXT Table in the SSOC computer, and the SXT Table uploaded to the satellite. However, the KSC computer did not register a mismatch. On a consecutive pass the Tables were compared again, with no error! This strange occurance has been examined extensively by the SXT super-tohban on duty (Kano san), but no explanation has been found. (2.) On Mar. 13, an persistent error during the KSC passes necessitated the issuance of an SXT HALT command by the SXT super-tohban (Hara san). This effectively shut down the SXT for a day. The error was eliminated during the next day's set of passes. Since this occurred coming off of a Yohkoh holiday (Sunday), the SXT Chief Observer faced a respectable data gap in deciding how to proceed with the choice of exposures. Ultimately, the plan to observe a filament channel was discarded. YOHKOH PASS CONFLICTS (1.) Yohkoh continues to have DSN pass-scheduling conflicts with the ASCA (ASUKA) satellite. On the average, Yohkoh has lost about 4 or 5 passes per week, over the past three weeks. The procedures set up to negotiate these potential conflicts have continued to work quite well. (2.) The SFU satellite was successfully launched this past weekend (March 18). Unfortunately, Yohkoh will lose some of its KSC *AND* DSN passes over the next couple of weeks to the new satellite. The operations group at ISAS is staying well-informed, and is prepared to make necessary adjustments. SEMINARS We have heard some excellent talks here at ISAS recently: T. Watanabe of N.A.O. spoke on "Chromospheric Extensions in the Sun and Stars". Following him, we heard a brief and interesting talk by Venkatakrishnan on the topic of CMEs. And in a last minute turnabout, M. Weber gave L. Acton's (MSU) brief presentation on the "Temperature Structure of the Diffuse Corona." In week 11, we had a similar plethora of speakers. H. Nakajima, of NRO/NAOJ, talked about "Magnetic Field Structure and Accelerated Electrons in a Gradual Microwave/Hard X-Ray Flare." He was followed hard-on-the-heels by K. Strong of LPARL, who gave a flashy little introduction to the TRACE project, entitled "TRACE". PERSONNEL L. and E. Acton departed for Montana on Saturday, March 4, leaving M. Weber to handle the SXT Chief Observer duties for a month. However, K. Strong arrived the following Monday, to do various research projects and to assist Weber with the Chief Observer duties. G. Linford left for the States as well, having completed the systems upgrade he had come to do. L. Shing has stayed an extra week to act as the SXT systems and data engineer. Week 9: Tohbans: SSOC: K. Akita, K. Shibata KSC: T. Shimizu, K. Muranaka SXT Chief Observer: L. Acton, M. Weber SXT Systems and Data Engineer: G. Linford Week 10: Tohbans: SSOC: H. Nakajima, K. Suga KSC: K. Muranaka, N. Kobayashi SXT Chief Observer: M. Weber, K. Strong SXT Systems and Data Engineer: G. Linford Week 11: Tohbans: SSOC: K. Hori, T. Matsuda KSC: N. Kobayashi, S. Koide SXT Chief Observer: M. Weber, K. Strong SXT Systems and Data Engineer: G. Linford