Aug_25_1999_H35.txt Shift H35 
        Start at 1999:238:02:00 GMT = 1999 Aug 25 10:00pm EDT
        End                           1999 Aug 26 06:00am EDT

See http://asc.harvard.edu/acis/SOT_reports/sot-shift.html, or 
/proj/ascwww/AXAF/extra/science/htdocs/acis/SOT_reports/Aug_25_1999_H35.txt.
   
SOT Lead	Ed Kellogg
SOT SC/ACA	Rob Cameron
FOT-SI		Eric Martin
HRC-SI		
ACIS-SI		

(Times: hhmm or ddd:hhmm, not precise.)

EVENTS							PLAN	DONE	OBSID
--------------						----	----	-----
AOS DSS-16, Goldstone					0740	0753	1250


NOTES/ISSUES/PROBLEMS 
--------------------- 
At start of shift, we were LOS. 

At 10:30 pm we met to review the p8 load. The p8 load is scheduled to
be uploaded shortly after 238:0740, and will start operation at 1134:

    There is a segmented maneuver between OBSIDs 162 & 52. The total
    maneuver angles are 49 & 140 degrees, and it's scheduled for
    240:02:28. This will occur when we are out of contact with
    DSN. The problem that led to safe mode last time has been dealt
    with by introducing a delay of 20 sec after the first maneuver,
    which is well in excess of the ~11 sec needed.

    There are two scheduled momentum dumps, in com. 

    We have adopted a standard procedure that  

	disables autonomous momentum unloading 30 min before a SIM YZ
 	move,
	disables spacecraft momentum monitoring 10 min before the SIM
 	move,
	re-enables the momentum monitoring 10 min after the
 	move,
	re-enables autonomous momentum unloading 11 min after the
 	move.

    OBSID 1232 has a roll constraint deviation by 2 degrees.

    The FID positions are updated and verified.

    ACIS-I default focus is at -536 steps.

    Marilyn did a 'diff' on the dot in the cxc mp directory vs. the
    actual one to be used ( they are not identical, a goal we will try
    to reach for the next load), and found that 

	    hi-res star search boxes >24 are edited to 24

	    lo-res star search boxes >3 are edited to 3

	    SIM focus adjust to -536 was added at 238:11:15

	    OTG operations were deleted at 240:07:55:02 and 242:01:58
	    because they are to be replaced by a CAP.

    CAP 338 is planned for ~5:30 pm EDT on Thursday, Aug 26. This will
    investigate why ACA is not finding faint stars. The SOT lead from
    the next (L) shift needs to brief this CAP at the 9 am Thursday
    review meeting.

	
At 0753 AOS, we had 4 out of 5 stars in ACA and 3 fids. The reported
magnitudes range from 9.3 to 9.6, whereas the catalog magnitudes in
the DOT range from 7.4 to 9.6, a much wider range. Rob showed a curve
that indicates the camera magnitudes are more in error as the star
color gets redder. Is it possible that we are seeing the effect of
interstellar reddening, so that the more distant stars are redder, but
since the silicon chip sees red better, they don't look as faint,
resulting in a very narrow range of observed brightnesses?

0758 Vacuum is 3.1e-6 torr.