To:sot_shift
from: Dan Schwartz
date: 08 Sep 99, 02:00pm EDT
Subject: SOT shift report, Shift L48
--------
See http://asc.harvard.edu/acis/SOT_reports/sot-shift.html, or 
/proj/ascwww/AXAF/extra/science/htdocs/acis/SOT_reports/Sep_08_1999_L48.txt.

Shift L48
	Start at 251:10:00  GMT
		 = 06:00am 08 Sep EDT
	End	   02:00pm 08 Sep
   
SOT Lead	DAS
Spac/Aspect	
FOT/Sci liason	
HRC		
ACIS 		

(Times will be given in GMT on day 251. In general
times are rough, not precise.)

PLAN
Continue running in P11, finish ACIS-I pileup studies observing
	PKS 0312-770, OBSIDs 1110 and 1111.
Start load P12 at 14:25, with an intermediate pointing position, 
	then a maneuver to Capella and a SIM motion to the HRC-S
	with the LETG. OBSIDs 1167 and 1244 on Capella prior
	to radiation belt entry at 252::02:07 (~10pm EDT
	Wed night). 
Next Comms, 13:25 to 14:30; 2220 to 252:0200; 10:25 to 12:10.

EVENTS
Start LOS. 

13:25 AOS
OBSID 1111 running 5 stars and 2 fid lights. Anomalous dither pattern. 
	This is actually 4 stars and 3 fids, see below.
14:30 LOS

NOTES/ISSUES/PROBLEMS
P12 was uploaded during the 06:45 to 08:30 pass early this morning.

No OCC SOT coverage for tonight's H-shift, since no real-time
	contact.

PROBLEM:  In OBSID 1111, an offset pointing at PKS0312-770, Rob
  notices glitches in the dither pattern. This is traced to the
  ACA having acquired a fid light in a slot that it thought was 
  a star. (During dither, the stars appear to move in the ACA, and
  the fids don't.) There seems to be a ground system problem which
  caused/allowed this star to be selected so close (<20 arcsec) to
  a fid light. Also, in this case the star magnitude was less than
  1.5 fainter than the fid light, so the fid light was NOT rejected
  as being too bright. Upon examination, Rob finds several other cases 
  where it seems the star is selected too close to the fid light -- 
  i.e., within 120 arcmin in one camera coordinate. 
  For future loads, P13 and beyond, we must check more vigorously
  for such cases.
  The OFLS team is looking at this to see if and where the problem
  arises.
  MIGHT THIS have caused problems with the aspect solution for 
  any previous observations?


24-hr science ops summary for 9am meeting:  
   ACIS-I Observing
   OBSID's 1104,1105  PKS 0312-77   OFF-axis PSF
	   1192,3,4,5 HR1099	    Off axis PSF
       1107,8,9,10,11 PKS 0312-77   Pileup
   No Radiation belt passage
   HRC-S in standby with reduced HV.
   All instrument performance nominal.

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