From ghurford@ssl.berkeley.edu Sat Jul 27 17:25:04 2002
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Subject: Tohban report - 2002 July 22-27
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Status: R

Spacecraft:	Routine operation with no notable anomalies.

Solar activity:	
Solar activity was moderate to high for part of this period. 
The highlight of the week, was the well-observed X4.8 event that
began at 00:18 UT* on July 23 and yielding our first
observations of gamma-ray line emission!  Additional M-class
events were observed on July 24/1555. 26/1830, 26/1902,
26/2210.  As with the X-flare, the latter M-flare was
accompanied by intense microwave emission at high frequencies. 

Ground station:	
BGS passes resumed on July 25.  Santiago downlinks ended the
following day.

Attenuator operation:
The thick shutter cut in during the rise of the X-flare and used
the remainder of its 5-motion allotment during the decay. 
Following up on the decision taken at last week's science/ops
meeting, the allotment was subsequently increased to 10
motions.  We still await implementation of the dead-time
hysteresis feature to prevent the toggling.  Attenuators were in
1-3 mode most of the week, except for the period from 25/2340 to
26/2159 when they were in 0-1-3 mode.  0-1-3 mode was
reactivated at about 27/2343.

Memory management:
This was fairly routine this week, thanks to the return of BGS
and intensive coverage by WLP and AGO.  SSR levels occasionally
exceeded 50%, but were quickly brought down.  No data were
excised. By the end of the period, the SSR level was at 21%.

Data issues:
The PMTRAS data gap issue discussed in previous meetings was
diagnosed by JRL to be associated with a full IDPU diagnostics
buffer being filled by monitor rate data.  (Such filling would
require only ~ 1 1/2 orbits so that a skipped pass would prevent
PMTRAS data being saved.)
A policy change to only activate monitor rates during actively
monitored passes should solve this problem, effective July 25. 
As of 7/27, however, there still seemed to be gaps, although
perhaps it is too early to tell.  Almost simultaneous with the
identificatin of its cause, a 50 minute gap in the PMTRAS data
from 0018 to 0108 on the 23rd coincided exactly with the X
flare.  An  interpolated PMTRAS roll solution was generated to
cover the 740 rotation gap, but its reduced (~1degree) accuracy
which will degrade azimuthal source positions for this event,
perhaps by ~10-20 arcseconds.  This degradation will be
alleviated when RAS data become available or when a more careful
interpolation of the PMTRAS solution can be done.
 
Next tohban:
The mantle of tohban was passed to Hugh Hudson effective July
28.