[AAVSO-HEN] GRB041006, optical observation in CrAO

[grb at aavso.org]

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TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  2798
SUBJECT: GRB041006, optical observation in CrAO
DATE:    04/10/12 20:51:02 GMT
FROM:    Vasilij Rumjantsev at CrAO  <rum at crao.crimea.ua>

V.Rumyantsev (CrAO), V.Biryukov (SAI, MSU),  A.Pozanenko (IKI) report:

We have observed the OT found by G. Da Costa, N. Noel and P.A. Price
(GCN2765) of GRB041006 (HETE #3570, M. Galassi, et al. GCN2770) with AT-64
telescope of Crimean Astrophysical Observatory. Several 120 s exposure
images in R-band were taken between (UT) Oct.6 17:11 - 22:40 under moderate
weather conditions and poor seeing. After inspection only 21 images
between Oct.6 (UT)18:33-20:27 is used for further reduction. Additional
observation on Oct. 7 reveals no OT. The data reduction against seven USNO
A2.0 field stars results to following magnitude of the OT and limiting
magnitude for October 7

Mean UT, exposure, mag,    S/N

Oct 6.81 21x120s   19.35R  3.8
Oct 7.85 64x120s   >20.0R  3

We do not apply a possible correction to a brightness of the field stars
suggested by D. Fugazza et al. (GCN 2782), A. Monfardini et al. (GCN 2790)
and P. Garnavich, X. Zhao, T. Pimenova (GCN 2792).

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