[AAVSO-HEN] GRB 080915: 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:  8228
SUBJECT: GRB 080915: ROTSE-III Optical Limits
DATE:    08/09/15 00:45:01 GMT
FROM:    Wiphu Rujopakarn at U AZ/Steward  <wiphu at as.arizona.edu>

W. Rujopakarn (Steward), H. Swan (U Mich), T. Guver (U Arizona) report on
behalf of the ROTSE collaboration:

ROTSE-IIIc, located at the H.E.S.S. site at Mt. Gamsberg, Namibia,
responded to GRB 080915 (Swift trigger 324744; Oates et al., GCN 8227),
producing images beginning 11.2 s after the GCN notice time. An automated
response took the first image at 00:03:42.2 UT, 52.2 s after the burst,
under cloudy conditions. These observations were affected by the full
moon. We took 10 5-sec, and 1 20-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. Individual images have limiting magnitudes
ranging from 14.0-14.3; we set the following specific limit.

start UT       end UT      t_exp(s)   mlim   t_start-tGRB(s)  Coadd?
--------------------------------------------------------------------
00:03:42.2   00:03:47.2         5     14.2           52.2       N