SXT Status Report
                         August 9 - August 30, 1998
                               (Weeks 33-35)

                           D. Alexander, H. Hudson


SUMMARY

Activity was moderate to high. There were minor operational problems
but SXT has operated well. The Whole Sun Fortnight (successor to the
Whole Sun Month campaign of 1996) took place amid the high activity.

SOLAR ACTIVITY

The GOES background level (see the plots, for example, on our weekly SXT Web
pages at http://www.solar.isas.ac.jp/sxt_co/index.html) remained above mid-B 
level, approaching the C level at times. In fact, during Aug. 30 the
GOES level was almost continuously above C!  There were at least 5 X
flares and 9 M flares; Yohkoh unfortunately missed the interesting part
of the event of August 24, an event with great geoeffective potential.
Large spot groups have been present continuously, with AR 8307 reaching
almost 600 millionths. All the commentators are predicting major activity.

OBSERVING CAMPAIGNS

The major effort during this period, guided on the SXT side by D. Alexander,
has been the Whole Sun Fortnight program (see
http://sohops.gsfc.nasa.gov/whole_sun/HOMEPAGE/WSM2/plans.html and 
http://www.solar.isas.ac.jp/~alexande/WSF/observations.html).
This effort will have produced data quite strikingly different from 
those obtained in the original Whole Sun Month, which took place during
solar minimum conditions of mid-1996.

SXT also observed the particularly well-situated eclipse of August 21-22,
visible on Earth in the South Pacific. For Yohkoh observations see
http://isasxa.solar.isas.ac.jp/~hudson/aug98_eclipse.html (predictions) and
ftp://isass0.solar.isas.ac.jp/pub/sxt_co/980829.html (results).
Unfortunately this operation, as has happened before, resulted in a temporary
spacecraft mis-pointing. Recovery from this condition has been slow because
it occurred during a period of relatively poor visibility for the star
Canopus, the fundamental roll calibration reference for Yohkoh.

SXT INSTRUMENT STATUS AND CALIBRATION ACTIVITIES

The terminator program has continued successfully. No new Yohkoh re-pointings
were necessary.

SCIENCE

The new "science nuggets" consist of:

29-Aug-98: Solar eclipse: 22-Aug-98 
22-Aug-98: X4 eruptive flare 
15-Aug-98: WSF Campaign -- Loop Brightening Observed by SXT and TRACE 

The URL's for these and the full list of science nuggets is on
http://www.solar.isas.ac.jp/sxt_co/index.html,
and the current week is also always kept on
http://www.solar.isas.ac.jp/sxt_co/SXTweekly.html.

OPERATIONS ISSUES

KSC passes lost to other ISAS spacecraft:

   Week 33: 6 passes lost to Akebono 
   Week 34: 5 passes lost to Akebono, 1 to HALCA
   Week 35: 2 passes lost to Akebono, 6 to HALCA 

The competing ISAS spacecraft now include Nozomi (the Mars mission) as well
as Akebono, ASCA, and HALCA. A Nozomi delta-V maneuver is cheduled for 28-29
August.
 
VISITORS AND PERSONNEL

Hugh Hudson was away from ISAS during most of the period.

SEMINARS

July 27 -  G. Simnett (University of Birmingham): "Corotating Interaction 
   Regions-Sources and Manifestations"
July 27 -  D. Alexander (Lockheed): "Magnetic Bananas and the 
   Non-Force-Free Corona"

Both of these are rich subjects related to the development of the solar
magnetic field above its photospheric boundary, and in the solar wind.
Simnett will return for a further discussion on Sept. 10. The bananas
referred to in Alexander's title are different bananas from those to be
found on the APOD Web page http://antwrp.gsfc.nasa.gov/apod/ap980629.html.

TOHBANS

Tohbans for Week 33

SSOC : Sakura, Hata 
KSC  : Kano, Saito-Y 
SXT_CO: Alexander 
SXT_SW: Slater, Shirts

Tohbans for Week 34
 
SSOC : Nishio, Watanabe_Te 
KSC  : Kano, Hanaoka 
SXT_CO: Alexander 
SXT_SW: -

Tohbans for Week 35

SSOC : Liu, Akita 
KSC  : Hanaoka, Ashizawa 
SXT_CO: Alexander, Hudson 
SXT_SW: -