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GCN Circular 6257

Subject
GRB 070406: further analysis of NOT images.
Date
2007-04-07T23:01:08Z (17 years ago)
From
Daniele Malesani at Niels Bohr Inst,Dark Cosmology Center <malesani@astro.ku.dk>
D. Malesani (DARK/NBI), H. Uthas (NOT), J. Hjorth, C.C. Thoene, J.P.U.
Fynbo (DARK/NBI), and M.I. Andersen (AIP), report on behalf of a larger
collaboration:

Following the identification of a candidate X-ray afterglow (Troja et al.,
GCN 6255) of GRB 070406 (Cummings et al., GCN 6247), we inspected again
our images taken with the NOT (Malesani et al., GCN 6254).

Inside the XRT error circle, we confirm the presence of a bright object,
present in the USNO and SDSS catalogs and already noted by Kann (GCN
6256). By comparing its magnitude with several other SDSS objects
(photometry as presented by Cool et al. in GCN 6248), we find r = 19.89 +-
0.07 (AB), where the error corresponds to the scatter between the
instrumental (R band) and SDSS (r band) magnitudes. Thus, even if this
object is related to the GRB, there is no evidence for afterglow
contribution at 24.9 hr after the trigger.

At the edge of the XRT error circle, we also note the presence of a second
object, barely detected in our image (r_AB ~ 23.7), with coordinates
(J2000, 1" error radius):

alpha = 13:15:51.15
delta = +16:30:50.9
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