ACIS Shift report L359 Jul 16 0800, GMT 198:12:00


PLAN:
 
   Examine EPHIN realtime rates in conjunction with ACE, GOES and Kp
data to decide if it safe to restart the load.  Warm boot the ACIS BEP
to clear any SEUs which could effect upcoming science runs.

SUMMARY:

   The radiation environment was too high to permit normal science
operations.  Nevertheless, I did warm boot the BEP and restart DEA
housekeeping. All was nominal.   The stored command load was disabled,
so Chandra is still in an "SI-safed" configuration.
    The overall trend from GOES and ACE is downwards, but rates are
still highly elevated compared to quiescent levels.

NEXT PLAN:

  The current ACIS motto is "reload for the next pass".   Our next COM
is from GMT 198:20:45 to 198:22:45.  Typically a CTI measurement would be
run starting at GMT 198:23:35.  So, we could consider starting a CTI
measurement in realtime if the EPHIN levels permit.  We could only do
this however if the JUL1700 load was put on the spacecraft and enabled
because we would need the load to stop the Science run and power-down
the video boards.  Also, RADMON would be DISABLED for this observation
since RADMON is typicallty disabled for all CTI measurements.
  
  Before 4pm today, we should consider the desireability and risk of 
this measurement.  My proposal for your review is:

1. Warm Boot the BEP	(for good measure, it only takes 5 minutes)
2. Restart DEA HKP
3. re-run CAP616 (CAP616_aciss_cti.*) to collect a CTI measuremnt on
the S array, we will get the I array on the outbound leg hopefully
4. rely on the load to stop the science run and power-down the video
boards at GMT 199:02:14.  Note, this would not be a usual stopScience, but
would be the usual radiation belt entry preparation commanding of
AA00000000, WSVIDALLDN, and RS_0000001.

Assumptions:
A. EPHIN rates are a factor of 3 below our on-board safing thresholds
B. JUL1700 load has been installed and activated on the spacecraft
C. RADMON is disabled for the CTI measurement

Comments, before 4pm please ?!?!


1) Detailed Timeline:

GMT
198:11:05   AOS on DSS 24
198:11:06   FP temp = -120.0 C, swHousekeeping and deaHousekeeping
	    running, ACIS TLM looks nominal
198:11:07   EPHIN rates
	    E150=13472, E300=3448, E1300=263, P4=5968, P41=85 cts/sample
	    altitude 132083 km
	    E1300 acceptable.  P4 is above the safing threshold of 
	    3542 and P41 is very close to the threshold of 100.
198:11:10   Decision is made at the 6:30AM telecon to stop the load.
198:11:11   We drop off to participate in the telecon to discuss the
	    high radiation environment.
198:11:35   Execute SOP 61070 to warm boot the BEP
198:11:37   Verify:
	    BEP normal boot
	    Flight SW version number = 30
	    warmbootFlag=1, patchValidFlag=1
198:11:41   Execute SOP 61010 to restart the DEA Housekeeping
198:11:43   verify deaHousekeeping TLM	       	    
198:12:42   EPHIN rates
	    E150=10336, E300=3112, E1300=170, P4=5248, P41=81 cts/sample
	    altitude 128294 km
198:12:45   LOS 


SOT LEAD: Dan Schwartz
ACIS: Paul Plucinsky