SXT Status Report 12 June - 18 June 1995 (Week 24) --------- Nariaki Nitta 18-Jun-95 The past 1.5 weeks have been devoted to coordinating with two campaigns that had different objectives. Because KSC passes took place early morning in Japan, corresponding to the observing hours of Kitt Peak, they were used to observe X-ray bright points. Then at the last pass another table was uploaded to observe an active region in coordination with Pic du Midi. Alan Kiplinger, Max 9X coordinator, and the campaigners were very responsive, and there was hardly any communication difficulty. For planning purposes, I often used the real-time GOES 5 min avearage plot on MOSAIC, as well as the SOON H-alpha images stored at NOAA/SEL. SOLAR ACTIVITY The activity level was so low (GOES A) with few B flares, we decided that it was a good time to observe XBPs. AR 7877, which was the target for the Pic du Midi campaign, did not grow as much as a BearAlert made us anticipate, but it showed nice expansion on the western limb, prpbably corresponding to a coronal enhancement as reported from Mauna Loa. PIC DU MIDI CAMPAIGN In the absence of no other regions that were active, we continued to observe AR 7877 during the second half of the campaign. The region started as an "anemone" type region (same as AR 7124, back in April 1992, which was also reported as a rapidly growing region by BBSO). It did not show intense X-ray emission after all, but produced many point-like and loop-like brightenings. In a sense it was good to select this region as the target, since it showed several loops appearing and disappearing and one of the objectives of this campaign was indeed to study the formation of loops. One thing we did not see in real time data was a jet or ejection, but data simultaneous with Pic du Midi may show it - these data belong to DSN downlink and will be reformated shortly. As AR 7877 approached the west limb, a filament southeast to it became darker, but it did not show a spectacular eruption while it stayed on this side of the disk. Instead, AR 7877 itself showed more change on the limb, especially expanding loops that probably led to a coronal enhancement as observed by the Mark 3 coronagraph at Mauna Loa. XBP CAMPAIGN The role of SXT Chief Observer for this campaign is to pick up an area that has many XBPs. Such an area often coincides with a coronal hole. We resumed the campaign Monday morning by observing an area near AR 7877 that had a narrow coronal hole channel, and then moved to areas near disk center. Then Karen Harvey suggested observing an isolated coronal hole near the eastern limb, which was identified on a HeI 10830 spectroheliogram. In spite of an SXT error that made us cancel the campaign for a day, we observed many XBPs in the rectangular field of view (3 (EW) x 1 (NS) mosaic). SXT INSTRUMENT STATUS The SXT instrument continues to be in fine working order. Only one SEU-related (Night Command) error and one Bitmap error occurred. The former one needed the full recovery plan, which was executed smoothly by skilled tohbans at KSC. CALIBRATION STATUS The offpoint terminator program continues. We identified a couple of offpoints at which terminators are most seriously missing, and changed 4 OGs to match those places. PASS CONFLICTS We lost a total of 7 passes due to conflicts with ASCA. SCIENCE I am extremely pleased to work at ISAS this time, because of these fantastic computer facilities. Now every machine has IDL installed, and some disks are allocated to store all the flare data. The only thing I can think of is missing is a postscript color printer. One thing I would like to report is the arrival of Tom Metcalf, who has developed a routine to reconstruct HXT images using "Pixons". While the maximum entropy method (MEM) seeks for the flattest image, Pixons picks up the image of the fewest pixels, i.e. it does not try to reproduce fine structures beyond the limit that is set by the raw data. It is always an issue how much one can believe an HXT image, largely because of noise being amplified. Pixons not only provides maps independent of MEM, but also indicates which features in MEM maps can be artifacts. We are looking forward to hearing Tom speak on Pixons at this week's Yohkoh seminar. SEMINARS A Yohkoh seminar was held on 14 June 1995. About 20 people attended. Speakers and titles were: 1. C. Foley: "Analysis of the Diffuse Corona above the Limb" 2. N. Nitta: "A Superhot Flare Observed by Yohkoh" PERSONNEL David Alexander arrived to take over as SXT Chief Observer. He will be here until early August. Tom Metcalf arrived for a 4-week stay. Week 24 Tohbans: SSOC: R. Kano, Y. Suematsu KSC: M. Ohyama, K. Ichimoto SXT Chief Observer: N. Nitta SXT Systems and Data Engineer: waiting for G. Linford to come (arr. 21st)