SXT REPORT FOR WEEK 6: 31 January - 6 February 1993 =================================================== General Status -------------- Another peaceful week. SXT continued to work well. The solar activity was higher than the previous week. Personnel --------- Keith Strong left ISAS on Sunday to spend a week in California. Dick Canfield left on Friday after a fruitful four-week visit. Next week Gary Linford and Hugh Hudson will leave on Wednesday and Thursday, respectively, and both of them will be in California for a week. Keith Strong will be back with Karen Harvey. Nariaki Nitta served as SXT Chief Observer on a temporary basis. The SSOC tobans were Dave Pike and Hiraoka-san, and the KSC tobans Suematsu-san and Akioka-san. Yohkoh Seminar -------------- Dick Canfield was the speaker. The title was "Pre-Impulsive Phase of the 15 Nov. X-Flare: Which came first - the Chicken or the Egg?" He had initially planned to talk on the dynamics of the filament during the pre-flare phase, using the SXT and MCCD data. But he ended up also emphasizing the importance of emerging flux as a mechanism to trigger the flare, thanks to useful suggestions by Kurokawa-san of Hida Observatory, who happened to be at ISAS during the first half of the week. Solar Activitiy and Interesting Events -------------------------------------- This week the solar activity was higher than the previous week. Thanks to the appearance of some active regions, the GOES background level was usually around C1. KSC data had two flares observed in flare mode. One was at 10:51 on 1 February and the other at 14:50 on 3 February. Both were observed in the new flare sequence that used only one filter (Be 119) so that we could see rapid variations if any in a same condition. Although neither of them was observed from the very early phase because they occrred just after night (first couple of minutes in day are used to illuminate UV light on to CCD), at least the latter one showed significant change in a short interval. Partial frame images were mostly on bright regions in the eastern hemisphere. At the beginning of the week, there were two bright regions on the eastern limb, later named NOAA 7417 and 7416. NOAA 7417 was characterized by high loops, whereas NOAA 7416 was more compact and flare productive. NOAA 7418 was probably an emerging flux region, which grew rapidly. Earlier in the week a large area was occupied by a coronal hole with low contrast with quiet Sun. Later, a darker coronal hole became visible in the southern hemisphere. Science Progress ---------------- There was hot discussion on emerging flux regions among Dick Canfield, Nariaki Nitta, Shibata-san, Kurokawa-san and his graduate student Kawai-san. Kawai-san showed coalignment of an SXT image of an emerging flux region on a simultaneous H-alpha data obtained at Hida Observatory, revealing the relationship between arch filament systems and X-ray loops. Hugh Hudson continued his work on impulsive brightneings in soft X-ray flares. He and Nariaki Nitta searched on the SXT movie to identify X-ray counterpart of type III radio bursts. Only a couple of jet-like structures were found. Operation Issues ---------------- We postponed off-pointing to the east, because there were not enough daylight passes. So only one table was uploaded this week to go back to a normal sequence. Archiving of the reformatted database to MO disks was started. For the next couple of weeks, Gary Linford and Greg Slater will be continuing it. We had several problems, mostly related to mainframe computers at ISAS. First, an SXT table was not transferred to KSC. Second, a routine to read Sirius database gave inconsistent results at different times. The bug was identified and it turned out that there were 14 such examples. In addition, we still sometimes failed to read Sirius database at all. The nameserver computer stopped working and we had difficulty sending e-mail from ISAS. Nariaki Nitta made a short manual in English for SSOC tobans, based on Japanese documents. The SXT-related work of SSOC tobans is not yet well defined. He also communicated with Dan Moses (NRL) to discuss how we can support their rocket experiment, scheduled for launch on the 8th. Nariaki Nitta, 6 February 1993