TITLE:   GCN CIRCULAR
NUMBER:  21708
SUBJECT: LIGO/Virgo G298048: uGMRT Follow-up of SSS17a at 400 MHz and 1.4 GHz
DATE:    17/08/26 01:23:58 GMT
FROM:    Mansi M. Kasliwal at Caltech  <mansi@astro.caltech.edu>

K. De (Caltech), K. P. Mooley (Oxford), P. Chandra (NCRA), V. Bhalerao
(IIT-B), A. Corsi (TTU), D. Kaplan (UWM), G. Hallinan (Caltech) and M. M.
Kasliwal (Caltech)

report on behalf of the GROWTH (Global Relay of Observatories Watching
Transients Happen) collaboration

We report on continued follow-up observations of SSS17a (GCN 21529; Coulter
et al.) with the upgraded Giant Metrewave Radio Telescope (uGMRT) following
the first epoch at 610 MHz (GCN 21603; De et al.). Observations were
carried out on UT 20 August 2017 08:00 at 400 MHz (200 MHz bandwidth) for
an on-source time of ~ 1 hour and on UT 20 August 2017 11:00 at 1.4 GHz
(400 MHz bandwidth) for an on-source time of ~ 2 hours.

After a preliminary analysis, no emission is detected at the location of
the optical transient at 1.4 GHz up to a 3 sigma upper limit of 100
microJy. The transient was also undetected at 400 MHz, although this
observation was partially affected by RFI and the analysis is being
improved. Further multi-frequency observations are planned.

We thank the GMRT staff for prompt scheduling of these observations. The
GMRT is run by the National Center for Radio Astrophysics of the Tata
Institute of Fundamental Research.