TITLE:   GCN CIRCULAR
NUMBER:  17650
SUBJECT: GRB 150317A: likely host galaxy detection
DATE:    15/03/28 03:20:50 GMT
FROM:    Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst  <malesani@dark-cosmology.dk>

Daniele Malesani (DARK/NBI), Nial R. Tanvir (Univ. Leicester), Zach Cano 
(Univ. Iceland), Pall Jakobsson (Univ. Iceland), and Tapio Pursimo (NOT) 
report on behalf of a larger collaboration:

We observed the field of GRB 150317A (Siegel et al., GCN 17592) using 
the Nordic Optical Telescope (NOT) located in La Palma. The mean time of 
the observation was March 23.95 UT, 6.77 days after the GRB. A 30 min 
exposure was collected using the SDSS i filter.

Inside the XRT error circle (Evans & Goad, GCN 17594), we detect a 
single source with i = 22.75 +- 0.25 AB (calibrated against nearby SDSS 
stars). The large error is mostly due to the bright, variable background 
from a nearby star. At the same position, an object with a consistent 
magnitude is also marginally visible in the archival SDSS data. Assuming 
that this object is coincident with the one detected by RATIR (Butler et 
al., GCN 17595), we thus suggest that this is the host galaxy of GRB 
150317A. Its coordinates are (J2000):

RA = 09:15:56.31
Dec = +55:27:58.0

with an uncertainty of 0.5". Such a bright galaxy may allow spectroscopy 
from an 8-m class telescope.