To:sot_shift
from: Dan Schwartz
date: 18 Aug 99, 02:00pm EDT
Subject: SOT shift report, Shift L27
--------
See http://asc.harvard.edu/acis/SOT_reports/sot-shift.html, or 
/proj/ascwww/AXAF/extra/science/htdocs/acis/SOT_reports/Aug_18_1999_L27.txt.

Shift L27
	Start at 230:10:00  GMT
		 = 06:00am 18 Aug EDT
	End	   02:00pm 18 Aug
   
SOT Lead	DAS
Spac/Aspect	RAC,DM
FOT/Sci liason	
HRC		JHC
ACIS 		PB,

(Times will be given in GMT on day 230. In general
times are rough, not precise.)

PLAN
Analyze safe mode entry telemetry
Start recovery from safemode.

When we return to OBC-A, HRC needs to disable SCSs for HV turn-on

EVENTS
12:50  Finish SSR playback. Reset pointers.
13:15  LOS from goldstone.
17:15  AOS Madrid

17:35  Start CAP 293 to recover from safe mode.  First 7 steps
	configure OBC command headers and certain SCS -- expected
	to take 40 minutes.
Note that all HRC HV related SCSs were already disabled, so HRC is 
  secure for the upcoming radiation belt passage.

NOTES/ISSUES/PROBLEMS
RAC looking at ACA puzzles around the safe mode entry.
The ACA command count of 24 is not understood, in terms of the number of 
search commands being sent.
It seemed that the ACA search commands were sent prematurely, during
the intermediate point of the maneuver. But we now understand that
the ACA PEA is reset during the RCTU switchover from side A to B.

It is not clear exactly when the safe mode recovery and cleanup can
be effected. However, the segment 3 SCS load must be built to start
at a specific exact time.
When the spacecraft is  out of the radiation belts at ~ 6am
on thursday morning, we plan to turn on HRC HV and take internal
calibration source data until the Segment 3 load resumes. This must
be in format 1, or at least we need to have format 1 while out of comm
in order to get the useful data.

As part of the safe mode recovery, PCAD will determine the pointing
direction, and then move to a standard position as part of a CAP.
We have chosen that position to be RA = 12.7484deg, dec = 66.400 deg, 
as a position on the great circle normal to the sun and nearest to 
CAS A (~14 deg away, roughly). SOT will choose stars and pass along
this target to PCAD to include in their CAP. 

Also, as part of ACIS recovery, we must turn on ACIS video boards
and start clocking out data, at least 2000 seconds before picking up
the Segment 3 sequence. 

-------------------------------------------------------
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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