SXT REPORT FOR WEEK 5 23 Jan. 1994 - 30 Jan. 1994 30 January 1994 Hugh Hudson GENERAL STATUS Normal operations continued. Both SXT and the Yohkoh spacecraft are working well. Solar activity continued at a medium level, with many flares including M-class events. PERSONNEL Nariaki Nitta left for California and Hugh Hudson returned to ISAS to act as chief observer. Canfield and LaBonte arrived from Hawaii, and it then snowed heavily on what must be the strongest Hawaii contingent ever present in Yohkoh service at ISAS. Canfield departed again for the IACG workshop in Easton, Maryland, but will return this week. Acton is to return in the first week of February and will take over as chief observer. SOLAR ACTIVITY The moderate level of activity level was due mainly to the return of the region that produced major activity over the Christmas and New Year's holidays. Its return spoiled the plans for a bright-point campaign in conjunction with Kitt Peak, even though huge coronal holes dominated the face of the Sun a week ago. The bottom dropped out on 30 Jan., however, with the (dramatic) disappearance of the W limb region. Right at the end there was a flurry of M flares, LDE's, CME's, and other excitement. There were about 7 M-class flares during the week. The coronal hole situation may be related to damage suffered by Canadian communications satellites, according to Vic Gaizauskas and Dave Speich. This damage occurred simultaneously on two "Anik" spacecraft on about 20 January. The presence of strong emission of >2 MeV (relativistic) electrons would be the prime suspect if this were the case, via spacecraft charging effects. We will see what happens on the next passage of the January hole. It is predominantly in the South, which is favorable for Ulysses observations. SCIENCE PROGRESS The M flare of 28 Jan. gave us another good luck at what appeared to be a "precursor" in the GOES plots. The search for such precursors was, a diligent reader of this chronicle will recall, a main part of Franta Farnik's research when he visited ISAS last year. Jan. 28 was a good example, because SXT was locked onto the active region in ARS2 to carry out the special scattering program (see below). As with the few events that Farnik found, this "precursor" turned out to be remote (but in the same complex of activity) from the subsequent flare, which was definitely not a re-brightening of preheated loop structure. Bob Bentley gave the Yohkoh seminar on Thursday, on the subject of relative timing between BCS blueshifts and hard X-ray bursts. This necessitated hard work on his part to identify timing problems among the various instruments involved - BCS, HXT, WBS, and BATSE, mainly. The scientific conclusions extended the work reported in an Ap.J. paper on this subject, namely that there is an extremely close relationship as a rule between the blue shifts and the hard X-rays. Following Bentley's talk, Dave Pike made some interesting comments about FeXXVI observations - there are now several dozen events to work with. Hudson was scheduled with a journal report on the "heart of darkness" of the chromosphere, namely the recent high-resolution CO observations in the infrared reported by Solanki et al., but this had to be deferred because of the usual vigorous discussion. SXT OPERATIONS SXT operations were mainly normal, with routine dark calibration and coronal offpoint sessions. We did make progress with special observations aimed at characterizing the scattering function of the SXT mirror, though, by running a special observing sequence table devised many months ago by Acton. This table had never been in place when a flare happened, but we got lucky on 28 Jan. and caught not one but two M-class flares. This should provide an extremely valuable data base for characterizing scattering as a function of temperature (effective wavelength of detected photons). It was proposed to revise the flare table, at least temporarily, to make it possible to track fast ejecta better. We're in the process of collecting suggestions on how to do this, so knowledgable readers please cooperate. At present I know about fast ejecta only in 15 Nov. 1991 and 21 Feb. 1992, please let me know about other examples. No special campaign observations are presently scheduled.