SXT Status Report
                      23 Apr - 30 Apr. 1995 (Week 17)
                                  ---------

                                James R. Lemen
                                   2-May-95



     Last week I reported about the cherry blossoms.  Now the azaleas
are blooming around ISAS.  We have created a new account on isass0
called called sxt_co = SXT Chief Observer.  All messages sent to the
sxt_co@isass0.solar.isas.ac.jp e-mail address will automatically be
forwarded to the appropriate SXT Chief Observer.  We hope this will
improve communications during observing campaigns. 

SOLAR ACTIVITY

     Week 17 was an interesting week from a solar activity point of view.
At the beginning of the week there X flares from AR 7864.  Then as AR7863
and AR7864 rotated over the west limb, the GOES level dropped over five
decades to A-level and it occasionally seemed to drop out all together.
We are perhaps at one of the lowest X-ray activity times since the launch.

     Last week I wrote a small program that only works at ISAS to
display the latest BCS spectra (the routine is called first_bcs).  It is
mainly used to display the temporary data that is received at KSC. 
Normally, one can easily see S XV spectra in fairly short integration
times.  However, after Ar7863/7864 rotated over the west limb it was no
longer possible to discern a S XV spectrum, even with relatively long
integrations (200s).  This is a consistent with the fact that all active
regions have disappeared from the disk. 

     The SXT can still seem many X-ray features: bright points, and various
loop systems at the east limb, and recently at the west limb and the faint
remains of a active region.


COORDINATED CAMPAIGNS

    The bright-point campaign was attempted one day this week, but it
was not successful for several reasons.  There were some operational
difficulties at KSC and the Chief Observer failed to communicate the
correct coordinates.  This campaign will be rescheduled for mid-June
1995. 

    Towards the end of the week we decided to put the SXT partial field
of view on a filament target.  The objective is to observe the X-ray
signature of a filament eruption with better time and spatial resolution
than we normally achieve with the half-resolution, full-Sun images. 
Kevin Reardon at the University of Hawaii is organizing the campaign and
selecting the targets from Mees observations.  In addition to Yohkoh and
Mees, the Soon sites are collaborating under Alan Kiplinger's coordination
and Big Bear is also a participant.

SXT CALIBRATION

     The off-point terminator program continues.   During the past
week Hirohisa Hara determined, after consulation with NEC spacecraft
engineers, the limits of the off-point maneuvers.

SXT INSTRUMENT STATUS

     SXT continues to function smoothly and without problems.  During
the past week there was one bit-map error and one warm reset error.  This
latter error requires a manual recovery operation.

YOHKOH PASS CONFLICTS

     We lost 7 KSC passes this past week due to conflicts with the
Japanese ASCA (five) and SFU (two) missions.  The operations of the
IRTS instrument (Infrared) on SFU ended this week and we hope that
there will be fewer conflicts with the SFU satellite.  Engineering
data will continue to be acquired for the next six months before the
SFU is recovered by the Shuttle.

SEMINARS

     On 26 April 1995 the seminar speakers were J. Lemen (LPARL) and
Jean-Pierre Wuelser (University of Hawaii).  The seminar featured two
flares.  Jean-Pierre spoke about the eruptive aspects of the 15-Nov-91
flare and I spoke about the 12-Jul-92 C5.3 flare.  The first flare
was large, eruptive, with Halpha ribbons, and the second flare was small,
gradual and somewhat compact with no evidence for any eruptions (although
there were plasma motions in the loop itself).

PERSONNEL
     
     At the moment, the SXT team at ISAS is represented by Hugh Hudson,
Jean-Pierre Wuelser, and J. Lemen.  Loren Acton arrived for a one-month
visit on 1-May-95 and Greg Slater will arrive on 3-May-95.  Loren took
over as the Chief Observer today and will continue as CO until the end
of May.

Week 17:
Tohbans:
   SSOC: A. Sterling, T. Takano
   KSC:  T. Yokoyama, A. Kubo
SXT Chief Observer:
   J. Lemen
SXT Systems and Data Engineer:
   (vacant -- fill in by JRL)