[vsnet-grb-info 11807] GRB 120320A: early optical upper limit

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  13198
SUBJECT: GRB 120320A: early optical upper limit
DATE:    12/04/03 18:22:28 GMT
FROM:    Alina Volnova at SAI MSU  <alinusss at gmail.com>

A.Volnova (SAI MSU),  E. Sinyakov (ISON), D. Varda (ISON), I. Molotov
(KIAM),  A.
Pozanenko (IKI) on behalf of  larger GRB follow up  collaboration report:

We observed the field of the Swift GRB 120320A  (Markwardt  et al.,
GCN 13071) with ORI-25 (0.25-m) telescope of ISON-Blagoveschensk
observatory. We took several unfiltered images of  60 s exposure on
Mar.20, starting (UT) 12:06:10, i.e. 10 min after trigger.

Within enhanced XRT position (Beardmore et al.,  GCN 13075) we do not
detect any  source in different combined images. Photometry is based
on nearby USNO-B1.0 stars, R2-values.

UT start,    t-t0           filter      Exp.        OT      UL (3 sigma)
              (mid, days)             (s)

12:06:10  0.00874    none     10x30       n/d      16.7
12:06:10  0.08435    none   360x30       n/d      19.2