TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  3657
SUBJECT: GRB 050721: optical afterglow confirmed
DATE:    05/07/21 06:59:54 GMT
FROM:    Daniele Malesani at SISSA-ISAS,Trieste,Italy  <malesani@sissa.it>

S. Covino, P. D'Avanzo (INAF/OABr), S. Bagnulo, T. Szeifert (ESO), D. 
Malesani (SISSA), G. Tagliaferri (INAF/OABr), G. Chincarini (Univ. 
Milano-Bicocca), S. Piranomonte, L.A. Antonelli, and L. Stella 
(INAF/OAR), on behalf of the MISTICI collaboration, report:

We observed the field of GRB 050721A (Antonelli et al., GCN 3654) with 
the ESO-VLT UT2. Observations were carried out with the FORS1 instrument 
in the R filter, starting on 2005 Jul 21, 4:54 UT (~25 minutes after the 
GRB) and are still in progress.

Inside the XRT error box, we find a fiding source at the approximate 
coordinates:

  alpha =  16:53:44.53
  delta =  -28:22:51.8

with an error of ~1".

This lies 1.1" E, 0.7" N of the USNO star U0600_22125777, and is likely 
the same source reported by Torii (GCN 3655).

This rapid response by an 8m-class telescope was possibile thanks to the 
special Rapid Response Mode provided by ESO.

This message can be cited.