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@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