SXT Status Report 15 - 28 May, 2000 (Weeks 21-22) N. Nitta, B. Handy SUMMARY Solar X-ray brightness decreased substantially, as regions with big spots either decayed or rotated off the west limb. Mostly routine operations. SXT has had no technical problems. SOLAR ACTIVITY The GOES background flux decreased roughly from C2 to B6 during the interval. Earlier, AR 8996 (1,300 millionths in sunspot area) and AR 9002 dominated the visible disk, later replaced with another big region AR 9017. There were 11 M-class flares, all occurring by 24 May. Repeated formation of TILs was seen to originate in a faint area west of AR 8996. OBSERVING CAMPAIGNS We did not officially participate in any coordinated campaigns, but occasionally observed AR 9002, which was the La Palma/TRACE target region. Please see our webpages for more details about campaigns past and future: http://isass1.solar.isas.ac.jp/sxt_co/sxt_catalog.html http://isass1.solar.isas.ac.jp/sxt_co/sxt_future.html SXT INSTRUMENT STATUS AND CALIBRATION ACTIVITIES No particular problems. We re-defined the Yohkoh normal pointing. In connection with the loss of Santiago coverage, we now keep track of how many downlinks were made every week at each station, including the one in Japan. The information is appended in this report. SXT OBSERVING SEQUENCE TABLES ------------------------------------------------- UT Date & Time Pass Table ID ================================================= 15-May-00 03:55 4 000514 P4 ARS1 DKCAL 15-MAY-00 22:57 1 000515 P1 ARS1 DIFF 16-MAY-00 04:04 4 000515 P4 ARS1 STD 17-MAY-00 02:31 3 000516 P3 ARS1 STD 18-MAY-00 00:58 3 000517 P3 ARS1 STD 18-MAY-00 23:25 2 000518 P2 ARS1 STD 20-MAY-00 01:16 4 000519 P4 ARS1 STD 22-MAY-00 01:35 4 000521 P4 ARS1 DIFF* 23-MAY-00 00:01 4 000522 P4 ARS1 DARK* 23-MAY-00 19:04 1 000523 P1 ARS1 QRFFI* 24-MAY-00 00:10 4 000523 P4 ARS1 STD* 24-MAY-00 19:12 1 000524 P1 ARS1 QRFFI* 25-MAY-00 02:03 5 000524 P4 ARS1 STD* 26-MAY-00 17:48 1 000526 P1 ARS2 QRFFI* 26-MAY-00 22:55 4 000526 P4 ARS1 STD* ================================================= Data reformatting is complete through 13-May-00 (week 00_20). SCIENCE Seminars: none scheduled. Science Nuggets 19-May-00: "We're Not Going Anywhere.", a follow-up on the 28-Apr-00 nugget. According to reliable prediction by Shuto-san at ISAS, Yohkoh's orbit will likely to last for another 10 years! That means we will have covered at least a full solar cycle. Extremely good news. 26-May-00: "Temperature of Flares as Derived from Yohkoh Data", another old story. While SXT provides easy views of the dynamic solar corona, quantitative analysis of SXT data is far from trivial. SXT temperature maps are compared with HXT L-channel images. The full list of nuggets is kept on http://isass1.solar.isas.ac.jp/sxt_co/index.html , and the current week's nugget also normally resides on http://isass1.solar.isas.ac.jp/sxt_co/SXTweekly.html . PERSONNEL B. Handy and G. Slater returned to their home institutes. H. Hudson left for Europe for a two-week trip. Czech visitor F. Farnik started a two-week stay. TOHBANS (spacecraft operators) Tohbans for week 21 SSOC: Y. Hanaoka, J. I. Khan KSC: M. Hagino SXT_CO: B. N. Handy, N. V. Nitta SXT_SW: G. L. Slater Tohbans for week 22 SSOC: M. Akioka, T. Yamasaki KSC: M. Hagino, H. Tonooka SXT_CO: N. V. Nitta SXT_SW: - NUMBER OF DOWNLINKS Week Wallops Santiago Goldstone Canberra Madrid Japan 21 25 0 0 2 0 24 22 27 0 0 2 0 28