SXT REPORT FOR WEEK 30: 17 JULY 1993 TO 24 JULY 1993


GENERAL STATUS

     SXT continued to work well, during a week that began with very low
levels of activity but has picked up a little towards the end.  
The biggest GOES event was C2.3!  SXT operations could be described as
routine. Hudson returned from the SPD meeting and resumed Chief
Observership from the triumvirate of Wuelser, Hara, and Shimizu.
    The main organizational activity this week was the coordinated
observation with the EISCAT facility in Norway and the VLA. The chief
object of these observations is to use the combination of scintillation,
radio, and X-ray data to characterize the quiet corona. The main players
outside Yohkoh are Coles (UCSD), Esser, Habbal, and Karovska (CFA),
Kojima and Misawa (STElab), and Markkanen (EISCAT). 
    The fruits of earlier efforts were available at the SPD meeting -
beautiful overlapping data from the corona and the disk obtained by
Yohkoh, SPARTAN, and NIXT from the coordinated data campaign of April
11-12.
    Finally, the first typhoon of the season is about to attack Japan,
aiming directly for Sagamihara on a beeline path that crosses over
Uchinoura - or so it seems.


PERSONNEL

     H. Hudson returned at the beginning of the week from the SPD
meeting. From LPARL, G. Slater returned July 22 and N. Nitta July 24;
M. Morrison departed on July 23 after a flood of last-minute useful
activities. ISAS is rather quiet because of the SPD meeting, but that
is changing. A crescendo of summer activity is expected to swell,
leading towards the Kofu meeting in September.


CAMPAIGNS 

     The observing campaign on July 23-24 coincided with the weekly
offpoint exercise for Yohkoh, and we have images showing the
development of the S coronal hole at the E limb just in time to arrive
at one of the specific regions of interest for the VLA observations.
     There are several joint observing campaigns scheduled over the next
month, summarized here:


Campaign     Dates      Proposer            SXT/CO   SXT/Coord   Special Ops

EISCAT/VLA   22-Jul-93  R. Esser (CFA)      Hudson   Hudson      Image ftp 
             23-Jul-93

Norikura     27-Jul-93  K. Ichimoto (NAOJ)  Hudson   ??          Tables
              2-Aug-93                                           Pointing? 

German/       3-Aug-93  T. Sakurai (NAOJ)   Hudson   Shibata?    Tables  
 Japanese    13-Aug-93                      Acton                Image ftp?

SERTS rocket 17-Aug-93  J. Davila (GSFC)    Acton    ??          Tables
                                                                 Pointing?  
                                                                 Image ftp?
                                                                 

Because of this good level of activity, we are thinking about a way
to achieve better organization of communications through the Yohkoh
bulletin board. If successful, this will allow participants to get full
data without relying on hit-or-miss communications between individuals.
The "Image ftp" entry above means that images are made available to the
non-Yohkoh observers to help guide their optimization. In the future we
hope that much of this can be done via the CRL anonymous ftp system. An
experiment with this for the EISCAT program has worked quite well. The
CRL system is not ready yet for general use, but may be in the near
future.


SCIENCE PROGRESS

     With few people present, little solar science was seen at ISAS
this week.  Hara and Morrison continued to develop the histogram view
of the mass of SXT data. An excellent seminar was presented by Syun
Akasofu, who said much the same thing he has been saying for two to
three decades, with the difference being that the data seem to have
caught up with him - there is growing evidence for a "driven" component
of flare energy release, as opposed to the "unloading" picture of the
classical build-up and triggered release of flare energy. The
attendance at this seminar was large and the discussion vigorous.


OPERATIONS     

     The routine coronal offpoint took place on Thursday, but not
without surprises - the SSOC operators did not plan automatically for
this event. This was because Chief Observer Hudson forgot to make
his weekly plan of table activity, which should be circulated at the
Monday operations meeting to avoid such surprises. The result of this
one was that BCS (thanks) had to defer a calibration sequence that
had been planned on top of the SXT campaign activities. We will try to
avoid this kind of confusion in the future. 
     With Watanabe-san at KSC, we have been attempting different ways of
getting terminator images at half resolution, thus far unsuccessful.


                                        Hugh Hudson, Jean-Pierre Wuelser 
                                        SXT Chief Observers