Aug_05_1999_H.txt Shift H15 (A15)
        Start at 1999:218:02:00:00 GMT
                = 1999 Aug 5 10:00pm EDT
        End       1999 Aug 6 6:00am EDT

See http://asc.harvard.edu/acis/SOT_reports/sot-shift.html, or 
/proj/ascwww/AXAF/extra/science/htdocs/acis/SOT_reports/Aug_05_1999_H.txt.
   
SOT Lead	Ed Kellogg
SOT SC/ACA	Tom Aldcroft
FOT-SI		Eric Martin
HRC-SI		Ralph Kraft
ACIS-SI		Fred Baganoff, Peter Ford

(Times will be given in GMT on day 218. not precise.)

EVENTS							PLAN	DONE	OBSID
--------------						----	----	-----
Start shift (10pm EDT 05 Aug 1999)			0200	0200	62486
Continue monitoring ACA fidlites, all at 9th mag		ongo
Enable RADMON						0300	0320
Start ACIS raw mode bias, SAP 61079			0500	0448	62723
Enable & activate SCS 207					0529

End shift (6am EDT 06 Aug)		day 218		1000
ACIS Raw data						1100		62722,1
ACIS CC/raw						1640		62720

NOTES/ISSUES/PROBLEMS
---------------------
At B-to-A shift change, 218:0020, Chandra was emerging from the
radiation zone, Vac monitor was 8.8e-6 torrs, ACA was monitoring 4 
fidlites in correct windows. As of 218:0409, HRC is on, low voltage
power only, EPHIN is nominal, and ACIS is in Thermal Standby mode.

The fidlite stability patch for the PEA's, designed to cure the problem of
ACA loss of fidlites, is coded and awaiting test at BBRC.

During the start of SAP 61079, there was uncertainty about the
version. The tar file had version 3.1 of the SAP, but no instructions
on which versions of the scripts to use. CAP 119, 7/30/99, instructs
us to use  2.0A of I_1_RAW_BIAS_A.ssc and I_1_RAW_BIAS_B.ssc , and
2.0B of I_1_SW_TEIGNORE.ssc, and 3.1 of SAP 61079 and SOP
61078. However, the versions of the scripts that SOC had were 3.1, leaving all
concerned perplexed. We need to make the system better, so we know
what is the correct script to use with a SAP or SOP.

At the beginning of the ACIS Raw Mode Bias, the initialization turns on
the video boards, which were shut off for perigee passage. The other
electronics were supposed to be left on. Some of the
front end processors(FEPs) must have shut off autonomously during
perigee. Inspection of
the power draw alerted the operators to this condition. Next they
recycled power  on the video boards and the FEPs. This brought ACIS to
an operational state, and we continued with the Raw Mode Bias data
collection. Inspection of the chip images showed normal
operation. 

After several hours of thought, Peter Ford reports that he believes
the above behavior may be a feature of the current software-plus-patch
in ACIS. There may be circumstances that result in an FEP being turned
off. It may also be that if we had just gone ahead with a science
run, the FEPs might have been turned on by ACIS, without a need to
send commands to recycle them. Further consultation with ACIS
engineers is needed and planned. It is presently thought that this
phenomenon would only occur after a Continuous Clocking 3x3 run. See
flt note 219.