April 6, 1992

SSOC OPERATIONS REPORT, WEEK 15 (March 31 - April 6)

   Operations generally proceeded normally. There were no SXT errors
except for case discussed below, not counting BIT MAP errors that do not
interrupt normal functioning.

   An SXT error of the NGT CMD type occurred on Thursday morning, 
following the BCS calibration during the night interval just preceding
the KSC station pass. This was caused by the mismatch between DP day
mode and SXT night mode. SXT had been put in CNTL MAN prior to the BCS
calibration, as is the practice to avoid taking images at night. On this
occasion no CNTL AUTO command was issued from the OP list after the 
calibration, and this was the cause of the problem. The KSC tohban had
requested this because of the general reluctance to do CNTL AUTO from
the OP list, but the occurrence of the error still caused surprise and
confused operation at KSC. The command list should have incorporated
an SXT DAY command, so that this was an operations error at SSOC. When
the KSC tohban remembered what had happened, the DAY command was issued
and normal operations resumed.

It is necessary to establish a regular policy for SXT commanding at times
of BCS calibrations or other occasions when CNTL MAN is required.

   There was an incorrectly scheduled DSN pass in the Monday morning OP
list. This was discovered by the KSC tohban and edited out in time.

   SXT conducted an active--region tracking experiment all week, on AR 7117.
This was quite successful. Activity decreased to a very low level, 
unfortunately. As a result of this practice, the SXT team is fairly confident
of its ability to set on active regions chosen by coordinating observatories,
such as the VLA or Hida. 

   The suggestion was made that some additional efficiency might be obtained
in BDR management if low--altitude passes at KSC could be used for downlink
only, with commands issued from the OP list as though KSC were a DSN station.
This additional flexibility would sometimes permit an additional BDR dump.
In such a case, normally we would request that the KSC operations only do
commanding on four station passes, so of course this possibility would 
depend upon whether or not four uplink passes would be sufficient for 
operations on that day.

   There have been problems with data reformatting through flare2. Shutoh-san
is aware of these problems and we are hoping for normal reformatting to
resume this week.

   The previous week's SSOC tobans had not handled fax communications with
DSN properly, and in fact their instructions are incomplete and confusing
on this matter. Kosugi-san is going to improve the instructions. The 
problem is that change requests on the preliminary schedule should be
faxed to one place, while last-minute change requests (always cancellations)
are faxed to another place, on a different form. If the tohbans handle this
incorrectly, the cancellations are not properly received at DSN and the
ground-station time is lost, not just for Yohkoh but for all other spacecraft
that DSN tracks. This is bad manners (``gyougi warui'') and should be avoided.

This week we requested an additional pass to cover a VLA observing 
interval, and it was granted. There were also many cancellations on the
DSN side as a result of Shuttle operations and a launch operation. 

   Neither of the SSOC tohbans was present on Sunday, in spite of the
fact that operations were proceeding normally. This caused a problem 
because of last--minute SXT table changes that were not correctly reflected
in the command list.

   An new photocopy machine was delivered. It is nice. The old fax machine
is still there. It caused several problems and needs service and/or 
replacement. Takahashi programmed the DSN fax numbers into its memory.
Half of the SSOC tohbans missed ``ohanami'' at NAOJ, and much to their
disgust, it didn't rain.

Hudson, Takahashi