[vsnet-grb-info 3538] GRB 060719: TORTOREM optical upper limits

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  5372
SUBJECT: GRB 060719: TORTOREM optical upper limits
DATE:    06/07/30 08:29:57 GMT
FROM:    Corrado Bartolini at Universita di Bologna  <corrado.bartolini at unibo.it>

A. Guarnieri, C. Bartolini, G. Beskin, S. Bondar, G. Greco, S. Karpov, 
D. Nanni, A. Piccioni, F. Terra, E. Molinari, G. Chincarini, F. M. Zerbi, 
S. Covino, V. Testa, G. Tosti, F. Vitali, L. A. Antonelli, P. Conconi, 
G. Cutispoto, G. Malaspina, L. Nicastro, E. Palazzi, E. Meurs, P. Goldoni,
on behalf of the TORTOREM Team report:

The field of GRB 060719 (Stamatikos et al. GCN 5339) was observed
by the TORTORA (Telescopio Ottimizzato per la Ricerca di Transienti
Ottici RApidi) wide-field fast camera (12 cm diameter, 20x25 deg FOV)
mounted on REM robotic 60-cm telescope located at La Silla (Chile). 
The burst was outside the camera field of view. The system was repointed
and the TORTORA began to acquire frames at 06:51:36 UTC (59 sec after trigger)
with 7.5 Hz frame frequency (0.128 exposure).
The summation of 100 frames with 12.8 s. effective exposure did not reveal
any source down to the B = 12.4 mag (3-sigma).
We performed the Fourier analysis of 15 min data set to search for the
periodic signal at the GRB position. 
The upper limit for the amplitude of sinusoidal variability is 
B=16.5 (1-sigma) over the 0.01 - 3.5 Hz range.

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