GCN Circular 413
Subject
Optical Observations of GRB990907
Date
1999-09-23T12:41:05Z (25 years ago)
From
Nicola Masetti at ITeSRE,CNR,Bologna <masetti@tesre.bo.cnr.it>
Optical Observations of GRB990907
E. Palazzi, E. Pian, N. Masetti, F. Frontera (ITESRE, CNR, Bologna),
P.M. Vreeswijk, E. Rol (U. of Amsterdam), H. Pedersen, J. Hjorth (CUO,
Copenhagen), J. van Paradijs (U. of Amsterdam and U. of Alabama in
Huntsville), C. Kouveliotou (NASA-MSFC/USRA), P. Leisy, A. Pizzella,
E. Pompei (ESO-La Silla), R. Mennickent (Univ. de Concepcion, Chile),
C.G. Tinney, F. Freeman, S. Lee, J. Hawthorn (AAO), R. McMahon, S. Maddox,
C. Singleton (IoA, Cambridge), and H. Jones (RSAA), on behalf of the
BeppoSAX and Amsterdam/Huntsville GRB optical follow-up teams, report:
"We obtained V band images of the GRB 990907 field (GCN #405 and
GCN #409) at the Anglo Australian Telescope with Taurus + MITLL2,
at the ESO 1.54m Danish telescope with DFOSC, and at the ESO VLT telescope
with FORS1, beginning 24.9 hrs after the GRB event. Images in other bands
(R and I) were also acquired as detailed in the following table:
Telescope Date (UT) Filter Exptime Limit mag. Seeing
(3-sigma)
AAT Sep 8.7698 V 480 sec 23.2 1".4
Danish Sep 9.3736 V 1600 sec 23.0 2".6
Danish Sep 9.3755 R 1600 sec 23.0 2".6
Danish Sep 9.3854 I 1600 sec 22.5 3".5
AAT Sep 10.7806 V 800 sec 22.7 2".8
VLT Sep 10.4111 V 180 sec 23.5 1".1
VLT Sep 10.4153 R 180 sec 23.6 1".1
AAT Sep 18.3736 V 960 sec 23.2 2".2
Photometric calibration was done using standard stars in the Landolt
field PG0231+051. Comparisons were made among the V, R, and I band
images with the Digital Sky Survey, between the two R and among the
five V frames taken at different epochs.
The comparison does not show any object with significant brightness
variations larger than 0.3 mag.
This message can be cited."