[vsnet-grb-info 3677] GRB 060904B: Optical observations at Crni Vrh

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  5511
SUBJECT: GRB 060904B: Optical observations at Crni Vrh
DATE:    06/09/04 05:40:46 GMT
FROM:    Jure Skvarc at OCV  <jure at ing.iac.es>

J. Skvarc on behalf of PIKA observing program at Crni vrh Observatory
reports:

We observed optical counterpart of GRB060904B (Swift trigger 228006)
using 60 cm robotic telescope at Crni Vrh Observatory, Slovenia.  A
variable object was detected at  ra=03:52:50.52, dec=-0:43:30.9.
The coordinates are derived using UCAC-2 catalog. 1-sigma accuracy of
these coordinates is about 0.2 arcseconds.

Alternating exposures using R and B filters were taken, starting 45 s
after the trigger was received. The following table contains start of
exposure (2006-09-04 UT), exposure duration in seconds and magnitude:

R filter:
2:32:02  90 18.21
2:37:32  90 17.01
2:43:03  90 17.11
2:48:33  90 17.79
2:54:03  90 18.19
2:59:37  90 17.66
3:08:27 180 17.78
3:13:23 180 17.79
3:17:50 180 17.99

B filter:
02:34:02 180 18.32
02:39:32 180 17.51
02:45:03 180 18.56
02:50:33 180 18.81

The magnitudes are derived using comparison stars from the USNO A2
catalog.  Estimated 1-sigma statistical uncertainty is 0.02 for R and
0.04 for B filter.



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