ATCA radio detections of GRB130925A

ATel #5531; Keith Bannister (CASS), Paul Hancock (ICRAR), Shri Kulkarni (Caltech), Assah Horesh (Caltech), Ashley Zauderer (Harvard), Tara Murphy (Usyd), Bryan Gaensler (USyd)
on 31 Oct 2013; 00:22 UT
Credential Certification: Keith Bannister (keith.bannister@csiro.au)

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We observed the long GRB/TDE candidate GRB130925A (GCN 15246, Atel# 5435) with the Australia Telescope Compact Array (ATCA) on the dates and frequencies as shown below. ATCA was in in the H264 configuration and 2 GHz bandwidth was used for each frequency.

GRB130925A was detected at all bands and epochs, although some detections are < 5 sigma

0237-233 was used as a phase calibrator for all observations.

The following flux densities and errors were obtained by fitting a synthesized beam to the cleaned maps:

 
2013 Oct 09.9 
Freq (GHz)	Flux density (uJy) 
5.5		167 +- 15 [Note 1] 
9		138 +- 14 
17		186 +- 14 
19		160 +- 13 
 
2013 Oct 14.9 
Freq (GHz) 	Flux density (uJy) 
5.5		84 +- 27 
9		188 +- 47 
 
 
2013 Oct 15.9 [Note 2] 
Freq (GHz)	Flux density (uJy)	 
17		177 +-51 
19		178 +-52 

Note 1: Occasional bandpass ripple was observed at 5.5 GHz on Antenna 4. When antenna 4 was removed from the imaging, GRB130925A was not detected. This measurement should be considered suspect.

Note 2: 0537-441 was used as a bandpass and flux calibrator for this observation. 0537-441 has not been referenced to the ATCA primary flux calibrator (1934-638) since 2013-05-11, so the absolute flux calibration could be in error by as much as 20%.

We thank the ATCA staff for facilitating these observations.