GCN Circular 6541

G. Greco (Bologna University), F. Terra (Second University of
Roma "Tor Vergata"), C. Bartolini, A. Guarnieri, A. Piccioni
(Bologna University), G. Pizzichini (INAF/IASF Bologna),
D. Nanni (INAF/OAR and Second University of Rome "Tor Vergata"),
R. Gualandi (Bologna Observatory) report:


We imaged the field of GRB 070612B (Grupe et al., GCN 6511
Not found
 
 
) with the
152 cm Loiano telescope in the Rc and Ic filters in clear sky conditions.

We do not detect any new sources in the combined images within the 
XRT error box (Grupe and Evans, GCN6521
Not found
 
 
) with the following upper limits:

tmid (UT)        filter        Exp.       Limit
June 13.917        Rc         3x1800      22.2   (3 sigma)
June 13.975        Ic         3x1200      22.0   (3 sigma)

We detect the faint source indicated by Cenko et
al. (GCN 6521
Not found
 
 
) at an Ic-band magnitude of 21.9+/-0.16

Magnitude and upper limits were estimated by comparison with the
USNO-B1 stars and are not corrected for galactic dust extinction.

The co-added Ic image, in which the comparison stars are marked, has been
posted in our public directory from where it can be retrieved
by sftp using
hostname: ermione.bo.astro.it
username: publicGRB
password: GRB_bo.
directory: GRB070612B

[GCN OPS NOTE(17jun07): Per author's request, the reference to "GCN 6517"
was corrected to "GCN 6521", and "GCN6514" was corrected to "GCN 6521".]