[AAVSO-HEN] GRB 070531: Liverpool Telescope Optical Observations

[grb at aavso.org]

The following is a GCN Circular circulated via the AAVSO network.
For an archive and more information on circulars visit:
http://lheawww.gsfc.nasa.gov/docs/gamcosray/legr/bacodine/gcn3_archive.html

TITLE:   GCN CIRCULAR
NUMBER:  6476
SUBJECT: GRB 070531: Liverpool Telescope Optical Observations
DATE:    07/05/31 03:55:08 GMT
FROM:    Andreja Gomboc at LT,ARI,Liverpool JMU  <ag at astro.livjm.ac.uk>

A. Gomboc (Univ. of Ljubljana), R.J. Smith, C.G. Mundell, A. Melandri, 
I.A. Steele, D. Carter, A. Monfardini, C.J. Mottram, S. Kobayashi, D. 
Bersier, M. Burgdorf (Liverpool JMU) and C. Guidorzi 
(Uni-Bicocca/INAF-OAB) report:

The 2-m Liverpool Telescope robotically followed up GRB 070531 (Swift 
trigger 280958, GCN 6475 Markwardt et al.) and started observing the field 
at 3.7 min after the trigger time with the RINGO polarimeter. Photometric 
observations started at 11.9 min after the trigger time.

In first images we do not detect any new object down to:

Filter        t_mid  (min from GRB)     Tot_Exp (s)      Lim
-------------------------------------------------------------------
r'                 13.2                  60              18.2
i'                 19.0                 120              17.9
------------------------------------------------------------------
Magnitudes were calibrated vs R2 and I mag from the USNOB1 catalogue.
Further analysis is ongoing.