[vsnet-grb-info 4805] GRB 070612B: optical observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  6541
SUBJECT: GRB 070612B: optical observations
DATE:    07/06/16 09:01:57 GMT
FROM:    Giuseppe Greco at U Bologna  <giuseppe.greco2 at studio.unibo.it>

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) 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, GCN6514) 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 6517 ) 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