GCN Circular 21571

P. K. G. Williams (Harvard), K. D. Alexander (Harvard), and E. Berger
(Harvard) report on behalf of a larger collaboration:

We investigated observations of the candidate optical counterpart to
LIGO/Virgo trigger G298048 in the NRAO Very Large Array (VLA) data archive.
The field containing the candidate was observed at both 1.51 GHz ("L band")
and 4.89 GHz ("C band") on June 10 and 23, 1984, as part of program AW0110.
The on-source integration times were 11.5 and 5.5 minutes, respectively. We
obtained images generated by the NRAO's VLA/AIPS data calibration pipeline
(L. Sjouwerman, in preparation), which automatically processed the data in
2009.

We see no persuasive evidence for radio emission at the location of either
the host galaxy or the counterpart candidates. We measure image RMS values
of ~180 and ~340 microJy near the candidates in the 1.51 and 4.89 GHz
images, respectively. Taking a flux density upper limit of three times the
RMS and a luminosity distance of 39.5 Mpc, these values correspond to upper
limits on the spectral luminosity of 10^27.0 and 10^27.3 erg/s/Hz at 1.51
and 4.89 GHz. Using the relation between synchrotron emission and star
formation rate presented by Yun & Carilli (2002 ApJ 568 88), the implied
star formation rate of the candidate host galaxy is less than 0.05 solar
masses per year.

For comparison, Alexander et al. (LVC GCNs 21545
Not found
 
 
, 21548
Not found
 
 
) report a VLA
radio detection
of 300 microJy at 9.77 GHz, and Bannister et al. (LVC GCN 21559
Not found
 
 
) report
ATCA radio detections of 600-400 microJy at 8.5--21.2 GHz. These values are
consistent with the archival limits.