[vsnet-grb-info 8134] GRB 090715A: ROTSE-III Optical Limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  9667
SUBJECT: GRB 090715A: ROTSE-III Optical Limits
DATE:    09/07/15 17:47:35 GMT
FROM:    Shashi Bhushan Pandey at ARIES, INDIA  <shashi at aries.ernet.in>

S. B. Pandey (U Mich), S.A. Yost (College of St. Benedict), W. Zheng,
F. Yuan (U Mich), report on behalf of the ROTSE collaboration:

ROTSE-IIIc, located at the H.E.S.S. site at Mt. Gamsberg, Namibia,
responded to the short-hard GRB 090715A (Swift trigger 357498,  Racusin J. L., GCN 9666), producing images
beginning 7.1 s after the GCN notice time. An automated response took
the first image at 17:26:05.1 UT, 25.9 s after the burst, under fair
conditions.
We took 10 5-sec and 10 20-sec exposures and imaging is ongoing.
These unfiltered images are calibrated relative to USNO A2.0 (R). 

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.
Individual images have limiting magnitudes ranging from 15.4-16.6; we
set the following specific limits.
start UT       end UT      t_exp(s)   mlim   t_start-tGRB(s)  Coadd?
--------------------------------------------------------------------
17:26:05.1   17:27:21.5        76     16.8           25.9       Y
17:27:36.4   17:32:18.5       282     17.4          117.2       Y


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