To:sot_shift
from: Dan Schwartz
date: 12 Oct 99 , 11:00am EDT
Subject: SOT shift report, Shift L81
--------
See http://asc.harvard.edu/acis/SOT_reports/sot-shift.html, or 
/proj/ascwww/AXAF/extra/science/htdocs/acis/SOT_reports/Oct_12_1999_L81.txt.

Shift L81. 
	Start at 285:11:00  GMT
		 = 07:00am 12 Oct EDT
	End	   11:00am 12 Oct
   
SOT Lead	DAS
Spac/Aspect	
FOT/Sci liason	
HRC		
ACIS 		

(Times will be given in GMT on day 285. In general
times are rough, not precise.)

PLAN
Continue running load P21b. Finish OBSID 131, ACIS-S/HETG observation
of PSR B0833-45. Start 50 Ksec OBSID 18, ACIS-I observation
of Trapezium Cluster.

EVENTS
Orbit apogee was at 08:19.
Out of Comm this shift. Next AOS at 17:00 with Madrid, until 18:30.

NOTES/ISSUES/PROBLEMS
Chandra's state from the last comm, at
285:06:40, was as follows:

       PCAD MODE              =       NPNT
       CONTROL LAW FLAG       =       NPNT
       Stars:                 =          5  
       FIDS                   =          3 
       RA                     =   128.862 deg
       DEC                    =   -45.193 deg
       ROLL                   =   100.892 deg
       Format                 =          2
       OBSID                  =      131
       SIM FA                 =       -467
       SIM TSC                =     75623 (ACIS-S)
       HETG                  =     IN
       LETG                  =     OUT
        HRC HV is OFF

From the 9am Standup Status meeting:
  Concern was expressed over setting up the test case for the ACIS
Card item L-004.  This says we should be in format 2 for 5 minutes
while moving into or out of the focal plane.  This may be slightly
ambiguous, as the actual requirement is to be sure we are in 
format 2 at least 5 minutes before the very first software command,
and for 5 minutes after the last stop science command, during a focal
plane observing session.
  W. Jackson explained one of the issues from the M79 shift report.
One of the batteries started at 96.8% depletion, instead of starting
at greater than 97% as is assumed.  Therefore its rate of discharge
calculated in the OBC exceeded the allowed rate, and triggered a 
glitch counter. In real time this was not immediately understood, but
has been determined not to be of concern since it takes 150 "glitch"
counts, in two or more batteries, to trigger an EPS safe mode.
  

ACIS has been observing a large number of parity errors in FEP0, 
which reads out chip S3 (when it is on).  A CAP is being prepared
for realtime dump of the FEP during an upcoming next comm pass,
probably at 08:30 EDT today.  This will be used to diagnose 
whether we just need to reset the FEP, or whether we
may be seeing hardware degradation.

-------------------------------------------------------
Dan Schwartz,	MS #3
das@head-cfa.harvard.edu  
phone: (617)495-7232    FAX:   (617)495-7356
cell phone: (617)512-5627   
pager: 800-759-8352 PIN 1636502
       or e-mail 1636502@skytel.com 
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