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GCN Circular 12043

Subject
EVLA afterglow limits on the high z GRB090429B
Date
2011-05-28T12:16:12Z (13 years ago)
From
Dale A. Frail at NRAO <dfrail@nrao.edu>
Dale A. Frail (NRAO), Ashley Zauderer (Harvard), Edo Berger (Harvard)
and Poonam Chandra (RMC) report on behalf of a larger collaboration:

We used the EVLA to image a field toward the Swift burst GRB 090429B
(GCNs 9281, 9288, 9290, 9298), for which a photometric redshift of
z=9.4 has been recently claimed (Cucchiara et al. astro-ph/1105.4915).

The EVLA observed at two frequencies (1 GHz bandwidth each) centered
at 4.93 GHz and 6.68 GHz on 2011 April 4.38 UT and 2011 May 6.13 UT.
No radio source is detected at the NIR afterglow position. Combining
the data from both epochs we derive a 3-sigma limit of 16.6 microJy.
This limit corresponds to a spectral luminosity of 2e31 erg/s/Hz.

We also reduced archival data taken at a frequency of 8.46 GHz on 2009
April 30.28 UT. The 3-sigma limit for this observation is 132 microJy.
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