[AAVSO-HEN] GRB 070412 Liverpool Telescope optical limit

[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:  6289
SUBJECT: GRB 070412 Liverpool Telescope optical limit
DATE:    07/04/12 13:17:35 GMT
FROM:    Andreja Gomboc at LT,ARI,Liverpool JMU  <ag at astro.livjm.ac.uk>

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

The 2-m Liverpool Telescope started observing the field of GRB 070412 
(Romano et al. GCN 6273) at 14.1 min after the trigger time.

At the revised XRT position (Romano et al. GCN 6282 and GCN 6287) we do 
not detect any new object in stacked images down to:

Filter      t_mid (min from GRB)    Tot_Exp (s)       Lim
------------------------------------------------------------------
r'             35.8                    720            22.0
i'             41.4                    720            21.3
------------------------------------------------------------------
Magnitudes were calibrated vs the USNOB1 catalogue.