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GCN Circular 13260

Subject
GRB 120422A: 272 GHz observations from SMA
Date
2012-04-24T16:44:53Z (12 years ago)
From
Antonio de Ugarte Postigo at IAA-CSIC <deugarte@iaa.es>
S. Mart�n (ESO), G. Petitpas (SMA), A. de Ugarte Postigo (IAA-CSIC, DARK/NBI) on behalf of a larger collaboration report:

We have observed the field of GRB 120422A (Troja et al. GCN 13243) with the Submillimeter Array (SMA, Hawaii, U.S.A.). Observations, with mean epoch  23.19 April 2012 (21.4 hours after the burst), were carried out with 8 antennas in very extended configuration at an average frequency of 272 GHz under excellent weather conditions (optical depth at 225 GHz ~0.03, equivalent to PWV~0.5mm). The short 57 minutes integration on source yielded a preliminary r.m.s. of 1.2 mJy. No source is detected at the position of the optical (Cucchiara et al. GCN 13245) and radio (Zauderer et al. GCN 13245) afterglow down to a 3-sigma limit of 3.6 mJy.

Considering the low redshift of 0.283 (Schulze et al. GCN 13257), this limit places GRB 120422A at the faint end of the luminosity distribution of mm/submm GRB afterglows (see Fig. 8 of de Ugarte Postigo et al. 2012, A&A, 538, 44), consistent with what has been seen for other local low-luminosity GRB/SN.

We acknowledge the excellent support of the SMA staff.
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