SXT Status Report 22 October 1996 - 17 November 1996 (Weeks 43-46) H. Hudson, N. Nitta, S. Savy SUMMARY Solar activity continued at a low level. SXT and Yohkoh continued normal operations and there was considerable joint observation with various SOHO programs. SOLAR ACTIVITY Solar activity has been extremely low during this period, except for the continued visibility of the complex of activity that began in April and (as AR7978) produced the X flare in July. At the present time there are small active regions on the Sun, including a new-cycle region in the north. SXT INSTRUMENT STATUS SXT remains in good health and continues to return excellent observations. Thanks largely to Acton's work during his visit, and to the success of the terminator image program, even the Al.1 composite images look quite good now. SXT CALIBRATION ACTIVITIES The software adjustments to the HXA sensor gain changes are complete, thanks to Jean-Pierre Wuelser and members of "software@isass0", and the ATT and ATR databases are now up to date. The terminator program is also completely up to date, and during this reporting interval we observed at a new offpoint position (3 arc min S/C W) and were able to get appropriate terminators almost in real time. PASS CONFLICTS ASCA conflicts continue to diminish in numbers because of orbit precession. There is a disquieting rumor circulating, to the effect that NASA may close the DSN 26-meter antenna network. If this happens, spacecraft in low Earth orbit such as Yohkoh will be restricted to Wallops and partial coverage at Santiago, apparently. In such a case we speculate that a large fraction of the non-KSC telemetry would be lost, and that our coverage would decrease significantly. CAMPAIGNS Several SOHO-related campaigns of scientific interest to Yohkoh took place, including JOP-3 (CME onset), JOP-033 (jets), and LOOPS observations inspired at St. Andrews. It is proving difficult (as expected) to predict a jet occurrence for JOP-033. Often one is visible in the real-time movie images (typically about 20 SFD frames from the KSC telemetry dumps each day), and information about its location can be passed on to SOHO. But it is cumbersome because observing time for the JOP is limited. Serious data reduction has really not begun yet (on the Yohkoh side) but the dream of getting spectroscopic information from CDS and/or Sumer on a true X-ray jet seems a bit elusive right now. As for CMEs, this reporting interval did not extend the success stories of 25 September and 5 October, in spite of the frequent deployment of JOP3 on SOHO. Again, this is a bit frustrating but perhaps understandable in that we don't have the foggiest idea when a CME will occur, although of course we do know what sorts of regions to look at. The two events from September and October are the first for which we know that we have simultaneous Yohkoh and SOHO observations of CMEs. We note again that the current low level of solar activity seems to be a help since the X-ray signatures of CMEs may be quite faint. Finally, we obtained context images of AR 7994 for SERTS, which was launched unfortunately during Yohkoh night (13-NOV-96 18:30 UT). We request that next time we be included as part of coordinated observations. For Yohkoh operations, 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 There have been many visitors to ISAS before, during, and after the Yoyogi "fifth birthday" conference: K. Phillips (RAL), R. Bentley, A. Phillips, and L. Harra-Murnion (MSSL), F. Farnik (Ondrejov), D. Gary (Caltech), M. Grande (RAL). Several persons from magnetospheric physics also dropped by briefly as they toured ISAS before or after their meeting in Kanazawa. Dale Gary, who is visiting Nobeyama Radio Observatory of NAOJ, was not treated very well, trying to depart on the last train for Kobuchizawa and getting a train to Kobuchi (opposite direction) instead. This allowed him to return unexpectedly to the "kompa" and have more beer with the tohbans. Manuel Grande's visit was motivated by a Mercury conjunction. Unbeknownst to most solar physicists, Mercury has an extremely active magnetosphere and is (in principle) a detectable X-ray source. In our previous analyses of the Mercury transit of 1994, little attention was paid to this possibility, and Mercury typically looked dark and opaque. We would like to encourage further analysis, though. By the same token visiting X-ray astronomers pointed out that comets - not just Hyakutake, but others - appear also to be strong X-ray sources. SEMINARS Oct. 24 Te. Watanabe (NAOJ) "Energetics of a Solar Active Region" Nov. 14 D. Gary (Caltech and NRO/NAOJ) "Microwave Spectral Imaging Using Spatial/Spectral MEM" Nov. 14: A. Phillips (MSSL) "One-sixth of my Thesis" These were all extremely interesting presentations, especially in light of results at the Yoyogi meeting. The sixth of the thesis was on the subject of superhot flares, and because of the visitors we estimated that 1/3-1/2 of the whole world's expertise on this subject was actually present for the talk. SCIENCE The Yoyogi "5th birthday" meeting went off very well. Although this was not a major international meeting, it had a very nice degree of breadth - ranging from reconnection within the "flux conserver" of a spheromak, to reconnection between members of a cluster of galaxies. Solar physicists are customarily amazed at how little attention the regular astronomers pay to the magnetic field, but the talks at this conference showed that there really is some progress being made. The Yoyogi meeting was characterized not only by fairly mature analyses of Yohkoh data (for example, the use of SXT images to measure coronal temperatures even in coronal holes), but also by continuing new discoveries (the CMEs of September and October and other interesting things related to this year's rather amazing complex of activity). We are looking forward of course to the 10th birthday! PERSONNEL Greg Slater and Nariaki Nitta arrived. Loren Acton returned following the Yoyogi meeting. Week 43 Tohbans SSOC: T. Yokoyama and G. Slater KSC: T. Shinkawa and T. Yoshida SXT CO: L. Acton Software: G. Slater Week 44 Tohbans SSOC: T. Watanabe and S. Yashiro KSC: T. Shinkawa and Y. Nishino SXT CO: L. Acton, S. Savy Software: G. Slater Week 45 Tohbans SSOC: H. Miyazaki and N. Shinohara KSC: K. Nishino and K. Shinoda SXT CO: S. Savy Software: G. Slater Week 46 Tohbans SSOC: S. Morita and H. Tonooka KSC: K. Shinoda and H. Watanabed SXT CO: N. Nitta Software: G. Slater