[vsnet-grb-info 10284] GRB110213A: RAPTOR Early Optical Peak and Plateau Measurements

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  11730
SUBJECT: GRB110213A: RAPTOR Early Optical Peak and Plateau Measurements
DATE:    11/02/14 23:04:03 GMT
FROM:    James Wren at LANL  <jwren at nis.lanl.gov>

J. Wren, W.T. Vestrand, P.R. Wozniak, H. Davis,
of Los Alamos National Laboratory report:

The RAPTOR telescope system responded to Swift trigger 445414
(V. D'Elia et al., GCN 11705) under fair observing conditions. Our
narrow-field instruments began observing the location at 05:17:58.2 UTC,
28.7 seconds after the initial BAT trigger.  We detect the optical
counterpart at the location reported by the Swift UVOT team.  The
counterpart brightens from below our threshold at around 100 seconds
after the BAT trigger.  It reaches a peak magnitude of 14.7 at T~300 s.
The counterpart then begins a steady decline to magnitude 16.0 at
T~2000 s.  At that point, the counterpart re-brightens to a plateau at
roughly magnitude 15.8 for about an hour before resuming the fading
behavior.  The following table gives a sample of our observations:

t-mid(s)    exp(s)     mag     mag-err
--------------------------------------------
143.80      10.0      15.23    0.03
352.60      10.0      14.68    0.02
2179.60     30.0      16.12    0.03
4522.90     30.0      15.58    0.03
7172.30     30.0      16.00    0.04

The unfiltered images were calibrated against the USNO-B1 R-band.