GCN Circular 20647
Subject
GRB 170208B WHT nIR candidate afterglow
Date
2017-02-09T16:50:56Z (8 years ago)
From
Nial Tanvir at U.Leicester <nrt3@star.le.ac.uk>
K. Wiersema, N. R. Tanvir (U. Leicester), A. J. Levan (U. Warwick),
R. Karjalainen, F. Riddick (ING) report on behalf of a larger collaboration:
We observed the field of Swift GRB 170208B (Siegel et al. GCN 20632)
with the 4.2m William Herschel Telescope on La Palma.
Images were obtained in the Y,J,H,K filters with LIRIS.
In the K-band exposure, for which the mid-time was 2.54 hr post-burst,
we find a source with magnitude K(AB)=21.1+/-0.1 within the revised
X-ray error circle (Goad et al. GCN 20635).
The source is absent (or very marginally present) in the other infrared
filters, which were observed somewhat earlier, to AB mag limits of
about 22.5 in each band.
The position of this source is:
RA(2000)=08:28:34.55
dec(2000)=-9:01:47.8
This is about 1.8 arcsec south of the steady optical source
seen by GROND and Pan-STARRS (Kruehler GCN 20640;
we note there was a typo in the declination coordinate
reported in GCN 20640, Kruehler priv. comm.).
We suggest that the K-band source is most likely the
afterglow of the GRB, and is not seen in bluer filters
due to dust extinction, while the optical source may be the
host galaxy.