SXT Status Report
                     15 Dec. 1997 - 28 Dec. 1997
                           (Weeks 51-52)

                     H. Hudson, S. Savy, M. Weber


SUMMARY

This is the final SXT status report from 1997. Solar activity relaxed
somewhat during this period, with no more than a handful of C-class
flares.  SXT continues to operate well. For a look at some of the 
interesting scientific items from 1997, please refer to

ftp://isass0.solar.isas.ac.jp/pub/yohkoh_in_1997/main.html,

which contains some reference material carried by Y. Ogawara to the 
recent IACG meeting in Moscow.

SOLAR ACTIVITY

The background GOES level dropped below B1 for the first time in
a while, but there continues to be solar activity. There were no
major flares, but from SOHO reports of flare-less halo CMEs there may 
have been greater activity on the invisible hemisphere.

SXT INSTRUMENT STATUS AND CALIBRATION ACTIVITIES

Data archiving is complete through Week 47 (ending Nov. 24, 1997). 

The handover to Wallops for ground-station scheduling is going
faster than we expected, and in fact faster than it should in
consideration of untested systems and the need for software updates.
The Wallops ftp mailbox is working well for exchanges of scheduling
files and deletion lists. One major problem is that there has been
an inexplicable set of errors in pass timing calculations listed by
Wallops. At the same time, despite their vow not to, DSN stopped
full scheduling information - their scheduling files now omit Wallops
and Santiago passes. However their times are right. The confusion
about the early handover has been compounded by its arrival just
at the end of the year, which is a heavy holiday everywhere but 
especially in Japan.
     At present, we are fully switched over to the Wallops side and are
trying to eliminate the bugs in the new system.

Activity was low enough on Dec. 26 to slip the "super-long" exposures
in for a day, just in time to observe the interconnecting structure
shown in the current "science nugget".

WEB-BASED SCIENCE REPORTS

The scheme of weekly reporting by the SXT Chief Observer on Web pages
has continued. The current "science nugget" is now at

ftp://isass0.solar.isas.ac.jp/pub/sxt_co/SXTweekly.html

which links to this report and other pages, the previous science
nuggets reported by SXT chief observers.

ftp://isass0.solar.isas.ac.jp/pub/sxt_co/971024.html  dimming
ftp://isass0.solar.isas.ac.jp/pub/sxt_co/971031.html  EIT Calroc
ftp://isass0.solar.isas.ac.jp/pub/sxt_co/971107.html  Nov 6 flare
ftp://isass0.solar.isas.ac.jp/pub/sxt_co/971114.html  Nov 14 LDE
ftp://isass0.solar.isas.ac.jp/pub/sxt_co/971121.html  Movies of ejecta!
ftp://isass0.solar.isas.ac.jp/pub/sxt_co/971128.html  X2.9 ejective flare
ftp://isass0.solar.isas.ac.jp/pub/sxt_co/971205.html  Solar cycle
ftp://isass0.solar.isas.ac.jp/pub/sxt_co/971215.html  Amazing arcade
ftp://isass0.solar.isas.ac.jp/pub/sxt_co/971221.html  AR development
ftp://isass0.solar.isas.ac.jp/pub/sxt_co/971228.html  Interconnection

The most recent entry deals with a trans-equatorial linkage between
two active regions, N and S. This sort of linkage had been noted in
the Skylab data, and in the Yohkoh context by Tsuneta and by
Canfield et al., the latter calling attention to the strong 
selection effect for AR's with like helicities to want to link.
In this case, although we don't have a report on the helicities
yet, we actually observed the linked structure develop, or at least
brighten up. It appears to tie into the cores of the two active
regions and to pass under high-lying loops associated with each.
Worth further analysis for sure!

PASS CONFLICTS AT KSC (Akebono, HALCA, ASCA)

Week 51, 7 passes lost due to Akebono. 
Week 52, 6 passes lost due to Akebono.

CAMPAIGNS

There were no formal campaigns during these two weeks. 

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

Hudson returned from a trip to California.  Weber departed for a
vacation in Wakayama.

SEMINARS

There were no Yohkoh seminars during these weeks. The seminar
series will resume in 1998.

TOHBANS

Tohbans for Week 51

     SSOC: N.Shinohara,  Te.Watanabe
     KSC : M.Torii, M. Tonooka
     SXT_CO: M. Weber
     SXT_SW: -

Tohbans for Week 52

     SSOC: Y. Kato, T. Kosugi
     KSC : S. Masuda, J. Sato
     SXT_CO: H. Hudson
     SXT_SW: -