To:sot_shift
from: Dan Schwartz
date: 18 Sep 99, 08:30am EDT
Subject: SOT shift report, Shift L58
--------
See http://asc.harvard.edu/acis/SOT_reports/sot-shift.html, or 
/proj/ascwww/AXAF/extra/science/htdocs/acis/SOT_reports/Sep_18_1999_L58.txt.

Shift L58
	Start at 261:09:30  GMT
		 = 05:30am 12 Sep EDT
	End	   08:30am 12 Sep
   
SOT Lead	DAS
Spac/Aspect	
FOT/Sci liason	
HRC		
ACIS 		

(Times will be given in GMT on day 261. In general
times are rough, not precise.)

PLAN
Running under load P15. Continue performing observation of
Pleiades. ACIS diagnostic load, P16, will interrupt and take
over at 13:30.

EVENTS
Start of shift, AOS at 9:30
S/C state at 10:00:
DSS-46, data at 64K with constant hits
       PCAD MODE= NPM
       Stars:   = 5
       FIDS     = 3
       RA       = 56.71498 (estim.)
       DEC      = 24.05147 (estim.)
       ROLL     = 104.46789 (estim.)
       Format   = 2
       OBSID    = 13
       SIM FA   = -535
       SIM TSC  = 92903 (ACIS-I)
       HETG     = 81.3,81.7 degrees (out)
       LETG     = 81.7, 79.8 (out)
	Alt     = 137,650 km, ascending
12:10 LOS

NOTES/ISSUES/PROBLEMS
Flight software has been seeing a Fixed Point Overflow error
in the OBC error log.  L. Yester provided email from A. 
Roteliuk which explains as follows:  ". . . the fixed point 
overflow is in the Radiation Monitor code where the count
of high radiation occurrances is incremented. This just means
Chandra was in a high radiation environment for certain
species of radiation for about 23 days straight. . . .If you
look at the high radiation threshold in the radmon K-constants you'll
see that most of them are set to 0.0; these are the ones that
aren't used in the algorithm and kept track of. So, either 
ignore those fixed point overflows, or set the radmon high 
threshold K-constants to something more reasonable. . . ."
So these are EPHIN channels which we aren't using, and we 
should agree to set them to the machine equivalent of 
plus infinity.

Next comm is 3 to 8pm EDT today. We do not plan SOT-Lead coverage, 
only the ACIS team to monitor that their on-going diagnostics
are proceeding.

On Sunday, the eclipse is 2:04 to 2:55pm EDT. We will have SOT-lead
and SI for observation -- no real-time operations are anticipated.

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