SXT Status Report
                   Jan. 31, 2000, to Feb. 13, 2000 
                            (Weeks 06-07)

                        D. McKenzie, H. Hudson


SUMMARY

An X-class flare! But joy about that was short-lived because
of the terrible blow about Astro-E. 

SOLAR ACTIVITY

Three M-class flares and the X flare (Feb. 5), bringing the
total this millenium to 12 and 1, respectively. We are eager
to see, of course, if the X-class shortfall of last year
(possibly related to the "Gnevyshev Gap"?) continues. At one
point (12 Feb) there were 13 numbered NOAA active regions,
and the GOES background level hovered around C1.

OBSERVING CAMPAIGNS

There were no coordinated campaigns, although there were VLA 
observations. We were greatly handicapped by uplink restrictions
at KSC during preparation for the Astro-E launch.

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. After consultation, however, we decided to 
redefine the Yohkoh normal pointing. This was done on Feb. 11, and
it means that we now have to start over again on terminator collection
in order to get the best-quality images. We believe we are efficient
at this after long years of practice! The new position has Sun center
about 50 arc sec E of its previous position. The reason for the move
is to distribute the low-level dark-noise effects we see at the W
limb particularly. Yohkoh pointing, incidentally, remains excellent. 

At the end of week 7 we learned that Santiago was ceasing its Yohkoh
tracking immediately, even without fulfilling the three weeks currently
in the planning cycle managed by Wallops. At the time of writing
we do not know the actual situation, but we do know that we rely
heavily on Santiago right now because of its key location for orbits
such as Yohkoh's. Its permanent loss, which we have been warned about,
will be a major one, and we hope it can be postponed.

Spam attacks and other hacker activity seemed to subside, but the
trans-Pacific network is getting very slow again.

Yashiro_san, while acting as SSOC tohban, repaired a small Y2K bug
in OP_FIRST_GUESS.

SXT OBSERVING SEQUENCE TABLES

-------------------------------------------------------------
UT Date & Time                    Pass    Table ID
=============================================================
Monday         31-JAN-00 03:53     2      000131 P2 ARS1 DIFF  
Tuesday        01-FEB-00 04:04     3      000201 P3 ARS1 DARKCAL
Wednesday      02-FEB-00 05:59     4      000202 P4 ARS1 STD
Friday         03-FEB-00 23:32     1      000203 P1 ARS1 STD
Sunday AM       5-Feb-00 23:54     2      000205 P2 ARS1 DIFF 
Sunday PM       6-Feb-00 03:20     4      000205 P4 ARS1 DARKCAL

Monday         06-FEB-00 22:24     1      000206 P1 ARS1 STD
Friday         11-FEB-00 04:19     5      000210 P4 ARS1 STD
Saturday       11-FEB-00 21:38     2      000211 P2 ARS1 STD
============================================================

SCIENCE

Feb. 4: "Time-lapse views and helioexalepidoptery." This nice
new word refers to the X-ray butterfly diagram. The nugget
shows solar rotation in various ways, and it seemed like th
right time to write an IDL procedure named "helioexalepidoptery.pro".
This can be re-used every half cycle or so to show the flapping
of the butterfly's wings - quite interesting even after only the
first half-cycle (almost).

Feb. 13: "Already an X-class flare in the new millennium."
An obligatory look at the big flare. Nice, but not necessarily
easy to figure. In particular, we saw little sign of eruption
even though a major CME occurred. The hard X-ray and soft
X-ray morphology did not look so easy to understand. No doubt
this flare requires more analysis than one nugget's worth.

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 .

SEMINARS

Feb. 3, "Relation between Thermal and Magnetic Properties
  of Active Regions" Dr. S. Yashiro (U. Tokyo). 

PERSONNEL

No changes. Brian Handy visited from his training camp, spouting
plausible Japanese at a great rate.

TOHBANS (spacecraft operators)

Tohbans for week 06

SSOC: S. Yashiro, Y. Suematsu
KSC:  M. Hata, S. Akiyama
SXT_CO: H. Hudson
SXT_SW: -

Tohbans for week 07

SSOC: H. Ishizaki, Te. Watanabe
KSC:  S. Akiyama, T. Yokoyama
SXT_CO: D. McKenzie 
SXT_SW: -