[AAVSO-HEN] GRB 090113: ROTSE-III Optical Limits

[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:  8807
SUBJECT: GRB 090113: ROTSE-III Optical Limits
DATE:    09/01/13 23:23:49 GMT
FROM:    Heather Swan at U.of Michigan/ROTSE  <hflewell at umich.edu>

H. Swan (U Mich), E.S. Rykoff (UCSB), T. Guver (U Arizona), T.A. McKay 
(U Mich), F. Yuan (U Mich), B. E. Schaefer (Louisiana State), R. Quimby 
(Caltech), report on behalf of the ROTSE collaboration:

ROTSE-IIId, located at the Turkish National Observatory at Bakirlitepe, 
Turkey, responded to GRB 090113 (Swift trigger 339852; H. A. Krimm, GCN 
8804), producing images beginning 6.4 s after the GCN notice time. An 
automated response took the first image at 18:49:02.4 UT, 503.2 s after 
the burst, under windy conditions. We took 10 5-sec, 10 20-sec and 30 
60-sec exposures. These unfiltered images are calibrated relative to 
USNO A2.0 (R). Imaging is on going.

Comparison to the DSS (second epoch) reveals no new sources within the 
3-sigma Swift/BAT error circle, for both single images and coadding into 
sets of 10; the field is not crowded. Individual images have limiting 
magnitudes ranging from 14.9-16.4; we set the following specific limits.

start UT       end UT      t_exp(s)   mlim   t_start-tGRB(s)  Coadd?
--------------------------------------------------------------------
18:49:02.5   18:51:08.2       125     16.6          503.3       Y
18:51:16.6   18:55:52.3       275     17.3          637.4       Y
18:60:45.7   19:05:21.5       275     17.3         1206.5       Y