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GCN Circular 398

Optical Observations of GRB990806
1999-08-09T17:51:28Z (25 years ago)
Elena Pian at ITESRE-CNR,Bologna <>
P.M. Vreeswijk (U. of Amsterdam), E. Palazzi, E. Pian, F. Frontera
(ITESRE, CNR, Bologna), M. Bessell (Mount Stromlo Obs.), J.  Hjorth, B.
Milvang-Jensen, H. Pedersen (CUO, Copenhagen), J. van Paradijs (U. of
Amsterdam and U. of Alabama in Huntsville), and C. Kouveliotou
(USRA/MSFC)  report on behalf of the Bologna/Rome, Amsterdam/Huntsville
and Copenhagen GRB optical follow-up teams:

"We have observed the error box of GRB990806 (Piro 1999, GCN 392)  at the
40inch telescope at the Siding Spring Observatory (3.8 hours after the
burst) and at the ESO Danish 1.54m telescope.  A log of the observations
is reported in the following Table: 

       Date       Telescope    ExpoTime  Band    Lim.mag. 
       (UT)                    (min)           (5 sigma, ap. rad.=FWHM)

 1999 August 6.76  40inch       40        R      22.0
      August 6.80  40inch       60        B      21.5 
      August 7.24  1.54m+DFOSC  50        R      22.8
      August 7.40  1.54m+DFOSC  10        B      22.4

Comparison between the 40inch images and Danish images does not reveal a
source varying by more than 0.3 magnitudes both in the R and B band.

The ESO Danish R-band image can be inspected at

This message is citeable."
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