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Radio Detection of the Type IIb Supernova 2011hs in IC 5267

ATel #3789; S. D. Ryder (AAO), S. W. Amy (CSIRO), C. J. Stockdale (Marquette), S. Van Dyk (Spitzer), S. Immler (NASA/GSFC), K. W. Weiler (NRL), R. Covarrubias (UIUC), A. Soderberg (Harvard/CfA)
on 30 Nov 2011; 02:35 UT
Credential Certification: Stuart Ryder (sdr@aao.gov.au)

Subjects: Radio, Supernovae

The Type IIb Supernova 2011hs (CBET #2902, ATel #3768) in the galaxy IC 5267 has been observed with the Australia Telescope Compact Array (ATCA) + CABB 2 GHz backend system on 2011 Nov 17.4 and 2011 Nov 24.5 UT at frequencies of 9.0 and 5.5 GHz. In the first epoch no source was detected above a 3-sigma upper limit of 0.15 mJy at either frequency. For the second epoch we detected a radio source at a position consistent with that measured optically, and fluxes of 0.66+/-0.16 mJy and 0.19+/-0.09 mJy at 9.0 and 5.5 GHz, respectively. This indicates that a week prior to maximum light as inferred from the optical spectra (CBET #2902) the supernova's radio emission at these frequencies had yet to peak and enter the optically-thin decline phase. Monitoring at these and other frequencies is continuing. We would like to extend our thanks to the ATCA staff for enabling these observations. The Australia Telescope Compact Array is part of the Australia Telescope which is funded by the Commonwealth of Australia for operation as a National Facility managed by CSIRO.