[vsnet-grb-info 3558] GRB 060801: no variability of optical sources

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  5392
SUBJECT: GRB 060801: no variability of optical sources
DATE:    06/08/03 15:13:42 GMT
FROM:    Daniele Malesani at SISSA-ISAS,Trieste,Italy  <malesani at sissa.it>

S. Piranomonte (INAF-OARm), S. Covino (INAF-OABr), D. Malesani 
(SISSA/ISAS), G. Tagliaferri (INAF/OABr), G. Chincarini (Univ. 
Milano-Bicocca), and L. Stella (INAF-OARm) report on behalf of the 
MISTICI collaboration:

We observed again the field of GRB 060801 (Racusin et al., GCN 5378, 
5382; Sato et al., GCN5381) with the ESO VLT equipped with the FORS2 
instrument. Standard star fields were observed in order to get a 
reliable flux calibration. We find a significant mismatch (more than 1 
mag) with respect to the USNO calibration. Adopting the naming 
introduced by Castro-Tirado et al. (GCN 5384) and Piranomonte et al. 
(GCN 5386), we find the following magnitudes for the four sources close 
to the XRT position:

 A: R = 21.95
 B: R = 23.71 (extended)
 C: R = 23.90
 D: R = 24.62 (extended)

Between the night of Aug 1 (mean time Aug 2.026 UT) and Aug 2 (mean time 
Aug 2.991 UT) we find no variability of any of the above sources up to 
~0.1 mag.

We acknowledge the excellent support from the ESO staff, in particular 
Oliver Hainaut.

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