TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  1492
SUBJECT: GRB020813: Early Time Magnitude
DATE:    02/08/15 04:12:47 GMT
FROM:    Cullen Blake at Princeton U.  <cblake@phoenix.Princeton.EDU>

G.G.Williams (Steward Observatory), C.Blake (CalTech/Princeton),
Dieter Hartmann (Clemson), and the S-LOTIS
collaboration report:

The error box of GRB020813 (HETE Trigger 2262, GCN 1471) was observed
in R band with the 0.6m Super-LOTIS telescope, located at Kitt Peak,
beginning at 4.42 UT on August 13, 2002.  In total, 110 individual 60s
images were taken.  By coadding the first 9 images, taken between 4.42
and 4.62 UT, the OT reported by Fox et al. (GCN 1470) was detected at
the 3 sigma level.  This represents the earliest detection of the OT
through a standard photometric filter.  Using F band photographic
magnitudes from the GSC2.2, the magnitude of the OT was determined by
comparison to several nearby stars.  We report an R band magnitude of
18.38+/-0.38 at UT 4.51.  This magnitude is consistent with a decay
slope of approximately -1 to the later-time R band data reported by
Masi (GCN 1484), Urata et al. (GCN 1485), and Kiziloglu et al. (GCN
1488).  Analysis of the rest of the S-LOTIS data is in progress.

========================================= 
OT 19:46:41.874 -19:36:04.81 (J2000)     
=========================================
R=18.38+/-.38 at UT 4.51 August 13, 2002.
=========================================


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