[vsnet-grb-info 20613] GRB 180512A: Upper limits from OSN

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22711
SUBJECT: GRB 180512A: Upper limits from OSN
DATE:    18/05/12 23:37:11 GMT
FROM:    Alexander Kann at IAA-CSIC  <kann at iaa.es>

A. de Ugarte Postigo (HETH/IAA-CSIC, Dark/NBI), L. Izzo, D. A. Kann 
(both HETH/IAA-CSIC), and A. Sota (IAA/CSIC) report on behalf of HETH:

We observed the field of GRB 180512A  (Deich et al.; GCN Circ. 22710) 
with the 1.5-m OSN telescope in Granada, Spain

Observations started at 22:15:35 UT (827 s after the GRB trigger) for 
OSN, and we obtained 8x60s images in the Rc band and 6x300s images in 
the Ic band. Observations were obtained in inclement conditions (bad 
seeing of ~3").

In our stacked images, we find no source inside the Swift-XRT error 
circle down to a 3-sigma limit of Ic (Vega) > 21. The calibration was 
performed using nearby stars in the SDSS catalog.