SXT Status Report
                      21 July 1997 to 11 Aug 1997
                            (Weeks 30 - 32)
                               H. Hudson 


SUMMARY

SXT continued to operate well. Solar activity was distinctly different
from a "solar minimum" level.

SOLAR ACTIVITY

In addition to the generally higher level of activity, which at the
end of the reporting period was approaching a GOES background level of
B2, the main excitement was a Bearalert announcing a new AFS and
emerging flux. The largest sunspot-group area during the interval was
about 150 millionths. There were about many C-class flares and only a
couple of days of extremely low activity, defined here as GOES signal
levels near background.

SXT INSTRUMENT STATUS

SXT continues to perform well technically. A one-day bakeout of the CCD
was successfully performed on July 30 with no problems except for the
usual one day's worth of ratty-looking data at elevated temperatures.

SXT CALIBRATION ACTIVITIES

There is some serious reassessment under way now on the pesky stray
light situation in the Al.1 images, a problem that we've had for
several years and have never achieved fully satisfactory understanding
on. The data base is in excellent shape and we hope that we can crack
the problem with this effort, being led by N. Nitta. The benefits would
be available retroactively in the form of improvements in the
long-awaited regeneration of the SFD composite-image data base.

PASS CONFLICTS AT KSC

Week 30:  7 passes were cancelled (1 HALCA, 6 Akebono)
Week 31: 10 passes were cancelled (4 HALCA, 6 Akebono)
Week 32:  8 passes were cancelled (4 HALCA, 4 Akebono)

CAMPAIGNS

There were coordinated observations with CDS during week 31, looking
at loop filling factors and at X-ray bright points. The latter was
preparation for a more serious effort later on in  August. In this
XBP program, we used 5" pixels in order to give CDS a better range of
targets for near-real-time selection. This has not been done very
much in previous SXT bright-point studies, because the 5" pixel
summations are notably harder to deal with photometrically than the
2.5" pixels, in spite of the better SNR from counting statistics. Lee
McDonald (MSSL) is leading the effort to characterize these data and
see if they can effectively be used for time-series temperature
characterization to go along with the CDS diagnostics.

For Yohkoh target planning, the SXT weekly observing plan is available
on the Web at
        http://www.space.lockheed.com/SXT/html2/First_Light.html
or with
        "finger campaign@isass0.solar.isas.ac.jp | more"        .

See http://sohowww.nascom.nasa.gov/operations/targets/today"
for SoHO target planning.

VISITORS AND PERSONNEL

Nariaki Nitta returned from Palo Alto. M. Kundu (now at Nobeyama)
visited and will return to give a seminar talk on the 14th.

SEMINARS

August 7

T. Sakurai (NAOJ),     "Highlights from Cool Stars"
H. Hudson (SPRC/ISAS), "Yohkoh discovery of hot sheaths around
                        cool prominences"

The former touched on many topics presented at the Cambridge "Cool
Stars" meeting, ranging from stellar cycles to the coronal response
to Alan Title's shag rug (better term than "carpet"?). The latter
announced the rather surprising recent Yohkoh observations of hot
material around quiescent prominences but well within the corresponding
cavities - an observation somewhat reminiscent of the well-known 21
Feb. 1992 "candle flame" flare, except that the time scales stretch out
to two rotations or more.

TOHBANS

Tohbans for Week 30:

    SSOC :  Morita, Shibata
    KSC  :  Torii, Takahashi
    SXT_CO: Hudson
    SXT_SW: -

Tohbans for Week 31:

    SSOC :  Nishio, Nakagawa
    KSC  :  Takahashi, Saita
    SXT_CO: Hudson 
    SXT_SW: -

Tohbans for Week 32:

    SSOC :  Hudson, Sakurai
    KSC  :  Saita, Yamashita
    SXT_CO: Hudson
    SXT_SW: -