GCN Circular 2288
Subject
GRB030329, optical observation in May
Event
Date
2003-06-27T22:29:44Z (23 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
M.A. Ibrahimov, I.M. Asfandiyarov, B.B. Kahharov (UBAI), A.Pozanenko (IKI),
V.Rumyantsev (CrAO), G.Beskin (SAO), I.Zolotukhin, A.Birykov (SAI MSU)
report:
We have observed the OT GRB030329 found by B.Peterson and P.Price (GCN 1985)
with 1.5m telescope of Maidanak High-altitude Observatory (UBAI). Several
VBR Bessel images were obtained in May and June 2003. Based on the field
photometry by A. Henden (GCN 2082) we estimate the OT magnitudes:
--------------------------------------------
Date2003 Mid UT exp fltr mag err
--------------------------------------------
May 07 17:00 1800 R 20.72 0.09
May 07 17:58 3000 B 22.77 0.30
May 07 18:33 1800 V 22.20 0.31
May 13 17:07 1200 R 20.93 0.43
May 15 16:46 3300 R 21.16 0.21
May 17 16:33 2100 R 21.76 0.20
May 17 17:19 2400 B 21.86 0.27
May 19 16:32 1800 R 21.53 0.19
May 19 17:29 3600 B 22.59 0.16
May 21 17:33 600 R 20.91 0.18
May 22 17:00 2700 R 21.15 0.09
Jun 01 16:55 2400 R 21.77 0.19
Using our previous observations (GCN 2219) we can determine that within the
error bars the OT brightness did not change in B filter over the period from
May 3 till 19. Our data in R filter taken on May 7 and June 1 are
consistent with the values reported by S.Zharikov et al. (GCN 2245, 2265).
The data on May 19 are consistent with measurement by K.Stanek et al. (GCN
2244) taken 13 hrs later.
Based on our "R" data set obtained with the same instrument we can conclude
that the OT re-brightness took place in May 21-22. However there are
apparent differences in brightness estimations in the nearest epochs of the
observations obtained by the other teams in May 21-22.
The magnitude on May 21 differs from that estimated 12 hours earlier (GCN
2244). The magnitude on May 22 differs from that estimated 3.5 hours later
(R. Burenin et al., GCN 2260). Taking into account published brightness
estimations one may suppose that during the period of May 21-22 the OT
experienced brightness variations as suggested by K.Stanek et al. (GCN 2244,
2259). However, the indicated differences are marginal (3.7 sigma), and to
confirm the variations cross-calibration of the data obtained by different
teams on May 21-22 is necessary. If brightness variation will be confirmed,
such kind of variations should be considered as the shortest ones observed
to date for the late afterglows.
The Maidanak data for May 21, 22 can be accessed at
http://grb.rssi.ru/GRB030329/, and the file names are:
030329_030521R_UB.fits and 030329_030522R_UB.fits
This message may be cited.