22 July 1996 Hugh Hudson SXT CHIEF OBSERVER'S REPORT AND TABLE PLAN SXT CHIEF OBSERVER'S REPORT for Week 29: 14-JUL-96 to 21-JUL-96 `When you come to a fork in the road, take it' - Yogi Berra SOLAR ACTIVITY The high activity of last week ended precipitously on the 14th (Bastille Day, celebrated with the last C flare) with the rotation around the W limb of AR 7978. Why it should have ended so promptly is a little puzzling, because this region featured coronal loops and CME launches. A difference image from the 14th showed that the rapid decrease was due to low-lying structures in the active region, something of a surprise. SXT INSTRUMENT STATUS No SXT errors. SXT continues to function well. The terminators are going (a) into Be, because of the extensive flare mode data in that filter, and (b) into thin Al at the 5' S/C E offpoint position. The latter is to support the deep exposures we did with SOHO two weeks ago. CAMPAIGNS We participated in a SOHO campaign (JOP045, Longcope and Fisher) to study transient brightenings with a mixture of instruments. We also exchanged data with Peter Young and Bill Thompson, who obtained CDS observations of a nice coronal loop in the NE on around 18 July. Coordination with the VLA (Benz) will happen on July 27. The details will be entered on the .plan file of campaign@isass0. SEMINARS July 18, 1996: D. Alexander, "Soft x-ray loop-top sources: physics or fiction? H. Hudson, "Litvinenko's theory of logN-logS" PROBLEMS The typhoon messed up the SXT table plan at the end of the week, and the table for the JOP047 campaign - which was ARS2 directed at an uninteresting patch of the corona - stayed in operation longer than needed. We felt grateful that the power at KSC was restored in time to bring Yohkoh back to life for the weekend observations. Table uploads are currently not permitted because of KSC problems. This is to be straightened out Monday, we hope, but in the meanwhile the table plan reflects this. SXT TABLE PLAN FOR WEEK 30 (22-Jul-96 to 29-Jul-96) There will be only one campaign that we currently know about, namely the VLA coordination on 27 July. The correspondent for this observation is Arnold Benz of Zurich, who was able to use similar observations from a previous coordinated activity effectively (ie, they've written a paper but I haven't seen it yet!). A dark calibration table will be loaded on Wednesday, and the weekly diffusers included as part of a standard table on Thursday. KSC Time (start) in JST Pass Table ID _____________(= UT + 9 hrs)______#_______________________________ Wednesday 24-JUL-96 05:20 4 960723 P4 ARS1 DKCAL Thursday 25-JUL-96 00:30 2 960725 P2 ARS1 STD+DIFF 25-JUL-96 03:56 4 960725 P4 ARS1 STD+LONG Saturday 27-JUL-96 22:02 1 960727 P1 ARS2 VLA LONG 28-JUL-96 03:11 4 960727 P4 ARS1 STD *** Please note that this table plan may change *** SPECIAL NOTE: This plan calls for a Pass #5 table upload on the final day before the weekend. The reason for doing this is to support VLA observations over the time range 1448-2250 UT (2348-0750 JST) as best we can. This should be discussed at the WOM - I suggest that it's OK but that the tohbans should be asked to understand the use of the the SXT HALT command in case of emergency. I judge that the risk here is worth the possible loss data over the weekend. I have checked and there is no "pass #6" following pass #5 in this case. Finally, the desired interval also requires a pass #1 table upload to be optimal, so this is a non-standard operation at both ends. Dumping Patrol images: We request that KSC tohbans continue to dump a patrol image each time an SXT table is loaded to facilitate the study of optimizing ARS parameters for an awfully, awfully quiet period. SSOC TOHBAN, please fax the preliminary OP list to D-tou when it contains a terminator so that the Chief Observer can suggest which OG's to use.