[vsnet-grb-info 28221] GRB 150428A: late-time radio observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  30324
SUBJECT: GRB 150428A: late-time radio observations
DATE:    21/06/26 13:58:18 GMT
FROM:    James Leung at U of Sydney/VAST  <jleu9465 at uni.sydney.edu.au>

James Leung (University of Sydney/CSIRO), Poonam Chandra (NCRA-TIFR),
Emil Lenc (CSIRO), Tara Murphy (University of Sydney), Ziteng Wang
(University of Sydney/CSIRO)

ASKAP J123409+065712 is a radio source found in a search of
Australian Square Kilometre Array Pathfinder (ASKAP) data (SB10736).
The radio source position is consistent with the enhanced Swift-XRT
position (Osborne et al., GCN Circ. 17768) and inconsistent with the
GROND source position (Knust et al., GCN Circ. 17767).

We conducted further observations of the radio source with the
Australia Telescope Compact Array (ATCA) and the upgraded Giant
Metrewave Radio Telescope (uGMRT). We summarise these observations in
the table below.

Date (UTC) | Telescope | Freq (GHz) | Peak Flux Density (uJy/beam)
------------------------------------------------------------------
2019/12/05 | ASKAP     | 1.4        | 363 +/- 56
2021/05/21 | ATCA      | 5.5        |  94 +/- 26
2021/06/13 | uGMRT     | 1.3        | 386 +/- 17

The fitted position of the radio source from the uGMRT observation is
RA: 12:34:09.296
Dec: +06:57:13.83

Observations of the radio source do not show any evidence for fading
in epochs separated by 555 days and we therefore conclude the source
is likely the host galaxy of GRB 150428A.

We thank CSIRO and GMRT staff for supporting these observations
during these especially difficult times.