Aug_11_1999_L20.txt Shift L20 (A20)
        Start at 1999:223:10:00:00 GMT
                = 1999 Aug 11 06:00am EDT
        End       1999 Aug 11 2:00pm EDT

See http://asc.harvard.edu/acis/SOT_reports/sot-shift.html, or 
/proj/ascwww/AXAF/extra/science/htdocs/acis/SOT_reports/Aug_11_1999_L20.txt.
   
SOT Lead	Ed Kellogg
SOT SC/ACA	Tom Aldcroft
FOT-SI		
HRC-SI		John Chappell
ACIS-SI		Paul Plucinsky

(Times will be given in GMT on day 223. not precise.)

EVENTS							PLAN	DONE	OBSID
--------------						----	----	-----
Start shift (06am EDT 11 Aug 1999)			1000	1000	62476
Continue monitoring 4 ACA fidlites, 6.6-10. magn	ongo
ACIS cooling to -50 C						1012
Activate HRC antico shield SOP 62037				1031
RADMON enabled CAP 70						1042
ACIS at -50							1129
End shift (2pm EDT 11 Aug)		day 222		1800



NOTES/ISSUES/PROBLEMS 
--------------------- 

At H-to-L shift change, 223:1000, Chandra was 5 hrs past perigee. ACA
was monitoring four fidlites in the correct window; high background
flag was set because of stray light. HRC was on, low voltage power
only, EPHIN was nominal, and ACIS began cooling to -50 C.

As of 1220, spacecraft configuration: IU-A, CTU-A, RCTUs A Side, OBC-A
Online, OBC-B Offline; both OBCs flt SW 4.8 on-orbit image; VDE-A
IOE-A, ADE-A, SPE-A/B, FSS-A/B, IRU-1 = LP, IRU-2 = LO, ATTITUDE
MONITOR ENABLED, autonomous unloading & RW momentum bias disabled,
momentum monitor fault safing action (SCS #9) disabled, RCTU command
wrap enabled, pointing is NSM (normal sun mode), 90 deg solar array
angle, vacuum 6.5e-6 torr, link via Canberra-DSN direct-512-LGA-B.


The ACC is open! We saw a pressure rise from 7.4e-6 torr up to 2.2e-5
and then decay back to 1e-5 in about 10 minutes. We also noted a
permanent shift in the position of the fidlites of order 1/2
arcsec. This will be discussed further in a flight note by Tom
Aldcroft. The HRC had its antico shield running throughout the opening
of the ACC, and saw no change in rate, indicating there was no sign of
any effect of the slight pressure rise on its operation.

Ed Kellogg