GCN Circular 1266
Subject
Type Ic SN2002bl (SN/GRB?) Radio Observations
Date
2002-03-09T23:27:40Z (23 years ago)
From
Edo Berger at Caltech <ejb@astro.caltech.edu>
E. Berger, S. R. Kulkarni, and D. A. Frail report on behalf of the
Caltech-NRAO-CARA GRB collaboration:
"On 2002, March 8.26 UT we used the VLA at 4.86 and 8.46 GHz to observe
the position of the peculiar type Ic SN2002bl in UGC 5499 (IAUC 7845). We
detect no radio source at the position of the SN down to a 2-sigma limit
of 0.1 mJy at both frequencies. The optical spectrum of SN2002bl shows
that it is similar to the peculiar type Ib/c SN1998bw and SN2002ap
approximately two weeks after the explosion (IAUC 7845). SN1998bw reached
a peak flux of 50 mJy at 4.9 and 8.5 GHz on the same timescale. Given that
the distance to SN2002bl (74 Mpc) is twice larger than the distance to
SN1998bw, we determine that SN2002bl is at least 125 times fainter in the
radio. On the other hand, SN2002bl can be up to 15 times brighter than
SN2002ap (d=10 Mpc) which had a flux of approximately 0.4 mJy on a similar
timescale (GCN 1237 and 1238; IAUC 7817).
Based on the upper limit of 0.1 mJy, and adopting a typical expansion
speed of 30,000 km/sec, we place an upper limit of 6x10^10 K on the
brightness temperature of SN2002bl at 8.46 GHz."
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