[vsnet-grb-info 2815] GRB 060203: RTT150 optical observations

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  4652
SUBJECT: GRB 060203: RTT150 optical observations
DATE:    06/02/04 07:39:42 GMT
FROM:    Irek Khamitov at TUG  <irekk at tug.tug.tubitak.gov.tr>

I. Bikmaev, A.Galeev, N. Sakhibullin (KSU/AST)
I. Khamitov, Z. Aslan (TUG), U. Kiziloglu (METU), E. Gogus (Sabanci Uni.),
R. Burenin, M. Pavlinsky, R. Sunyaev (IKI)

report:

The field of XRT position of GRB 060203 (Swift BAT Trigger 180151,
Retter et al., GCN 4641, GCN 4644) was  observed with Russian-Turkish
1.5-m telescope (RTT150, Bakyrlytepe, TUBITAK National Observatory,
Turkey) by using Andor CCD.

We made series of 30 sec exposures in Rc and V filters, and series
of 60 sec exposures in B-filter on February 04, 00:20 - 03:50  UT.

We confirm the presence of the fading optical transient found  by
Malesani et al. (GCN 4645) and Genko et al. (GCN 4646) and
estimate its magnitudes (relative to R = 18.1, V = 18.7, and B = 19.6
of nearby USNO star U1575_02633321) on our co-added frames as follows:

Rc = 19.9 +-0.1  UT(mean) = 00:49  ( 54 min after the burst)
V  = 22.3 +-0.3  UT(mean) = 01:33  ( 98 min   )
B  > 23          UT(mean) = 02:07  ( 2h 12 min)
Rc = 21.0 +-0.1  UT(mean) = 02:49  ( 2h 54 min)
V  > 22.5        UT(mean) = 03:05  ( 3h 10 min)


By using our and published R magnitudes the estimated
power law decay slope is -0.90+/-0.04
(http://www.tug.tubitak.gov.tr/~irekk/grb/grb060203/grb060203.jpg)

The red spectrum of OT is supporting also by IR data of Bloom et al. (GCN 4648).


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