TITLE:   GCN CIRCULAR
NUMBER:  21639
SUBJECT: LIGO/Virgo G298048: ASKAP observations of SSS17a and NGC 4993 at 1.345 GHz
DATE:    17/08/22 07:23:04 GMT
FROM:    Tara Murphy at U of Sydney  <tara.murphy@sydney.edu.au>

D. Dobie (University of Sydney), A. Hotan (CSIRO), K. Bannister (CSIRO),
T. Murphy (University of Sydney), D. Kaplan (UWM), C. Lynch (University of
Sydney),
on behalf of the ASKAP/VAST collaboration.

We have observed the LIGO/Virgo localisation region (LVC GCN 21527)
with the Australian Square Kilometre Array Pathfinder (ASKAP) at a
central frequency of 1.345 GHz with a bandwidth of 192 MHz. Observations
started at 2017-08-19 05:34 UT and ended at 2017-08-19 07:58 UT.

We do not detect any emission at the position of the possible optical
counterpart SSS17a (Coulter et al. LVC GCN 21529), or its candidate
host galaxy NGC 4993. The upper limit for NGC 4993 is consistent with
a spectral index of -0.7 found by fitting the measured results from
the ATCA (Bannister et al. LVC GCN 21559) between 8.5 and 21.2 GHz.

Further analysis of our observations is ongoing.

Thank you to CSIRO staff for supporting these observations.