[vsnet-grb-info 16312] GRB 150317A: NOT optical observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  17593
SUBJECT: GRB 150317A: NOT optical observations
DATE:    15/03/17 05:44:01 GMT
FROM:    Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst  <malesani at dark-cosmology.dk>

D. Xu (DARK/NBI), D. Malesani (DARK/NBI), P. Blay (IAC, NOT), P. 
Jakobsson (Univ. Iceland), report on behalf of a larger collaboration:

We observed the field of the Swift GRB 150317A (Siegel et al., GCN 
17592) with the NOT equipped with the AlFOSC camera. A single 300-s 
R-band exposure was secured, starting at 04:48 UT (25 min after the GRB).

No new sources are detected within the X-ray position reported by Siegel 
et al. (GCN 17592), but we remark that in our image the bright glare 
from the nearby R=11 USNO star 1454-0197654 covers part of the XRT error 
circle. The limiting magnitude of our image is R ~ 21.5, but it is 
considerably shallower in the regions contaminated by the star PSF.

It cannot be excluded at the present time that the X-ray source detected 
by XRT is due to the USNO star. Visual inspection of the BAT error 
circle also does not reveal any new object compared to archival DSS and 
SDSS images, down to R = 21.5.