[vsnet-grb-info 23522] LIGO/Virgo S190814bv: ATCA observation of ASKAP J005547-270433/AT2019osy

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  25621
SUBJECT: LIGO/Virgo S190814bv: ATCA observation of ASKAP J005547-270433/AT2019osy
DATE:    19/09/03 01:20:02 GMT
FROM:    Dougal Dobie at VAST  <ddobie94 at gmail.com>

Dougal Dobie (University of Sydney/CSIRO), Emil Lenc (CSIRO),
Ian Brown (UWM), Tara Murphy (University of Sydney), Adam Stewart
(University of Sydney), David Kaplan (UWM), Kunal Mooley (Caltech),
Gregg Hallinan (Caltech) and the OzGrav, JAGWAR and GROWTH collaborations.

We observed ASKAP J005547.4-270433/AT2019osy (GCN 25487) with the
Australia Telescope Compact Array (ATCA) on 2019 August 29
from 14:00-22:00 UT.

We report flux densities of:

  369+/-23 uJy at 5.0 GHz
  335+/-19 uJy at 6.0 GHz
  307+/-15 uJy at 8.5 GHz
  278+/-14 uJy at 9.5 GHz

Fitting a power-law to these values we find a spectral index of
alpha=-0.39+/-0.11, consistent with the value of -0.42 found by
Mooley et al. (GCN 25539).

Comparing to the VLA observations reported by Mooley et al. (GCN 25539),
we find that the flux density has increased by ~40% in 1.5 days across
4.5-10 GHz.

Additional epochs are required to separate intrinsic variability from
contamination from propagation effects and systematics due to differing
spatial resolution between the ATCA, VLA and ASKAP.

Thank you to CSIRO staff for supporting these observations.