TITLE:   GCN CIRCULAR
NUMBER:  29053
SUBJECT: VLA observations of GW170817 at ~3.3 years post-merger
DATE:    20/12/16 01:40:37 GMT
FROM:    Kate Alexander at Northwestern U  <kate.alexander@northwestern.edu>

K. D. Alexander, A. Hajela, R. Margutti, J. Bright (Northwestern U.), T.
Eftekhari (Harvard U.), A. Kathirgamaraju (UC Berkeley), and E. Berger
(Harvard U.) report on behalf of a larger collaboration:

We observed GW170817 with the NSF’s Karl G. Jansky Very Large Array (the
VLA) at t =1216 days (~3.3 years) after the binary neutron star merger
(joint program SL0449, PI: Margutti). In our preliminary analysis, no radio
emission is detected at the location of GW170817; we infer a 3-sigma upper
limit of ~13 microJy at a central frequency of 3 GHz. Assuming the X-ray
flux density recently reported by Hajela et al. (GCN 29041) and a simple
power-law spectrum, this is fully consistent with the F_nu ~ nu^-0.575
spectrum observed throughout GW170817’s earlier evolution (e.g. Hajela et
al. 2019).

We thank the VLA staff for scheduling and executing these observations.