[vsnet-grb-info 28395] GRB210724A: MeerLICHT upper limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  30498
SUBJECT: GRB210724A: MeerLICHT upper limits
DATE:    21/07/24 22:56:14 GMT
FROM:    Simon de Wet at University of Cape Town  <dwtsim002 at myuct.ac.za>

S. de Wet (UCT), P.J. Groot (Radboud/UCT/SAAO), A.J. Levan (Radboud),
P.M. Vreeswijk (Radboud), report on behalf of the MeerLICHT consortium:

Following the detection of GRB210724A by Swift and its X-ray
counterpart (D'Avanzo et al., GCN30497), the 0.6m MeerLICHT telescope,
located at Sutherland, South Africa obtained a repeating series of
60s images in the q,u,q,g,q,r,q,i,q,z bands. Observations began at
2021-07-24, 20:25:18.02 UT, 11 minutes after the Swift detection,
and 2 minutes after the distribution of the BAT alert, and continued
untill 21:27:36 UT.

We detect no optical afterglow at the XRT position (D’Avanzo et al.
GCN30497) in our first u,g,q,r,i,z exposures to 5-sigma limiting
magnitudes of:

u > 18.59 at 20:27:37 UT
g > 19.40 at 20:31:01 UT
q > 19.77 at 20:25:49 UT
r > 19.38 at 20:34:31 UT
i > 19.26 at 20:37:45 UT
z > 18.14 at 20:59:12 UT

Full moon conditions limited the depth of our exposures.

We do note that an r=21.5 object is visible within the XRT localisation
in PanSTARRS imaging of the field, and is a plausible host galaxy.

MeerLICHT is built and run by a consortium consisting of Radboud
University, University of Cape Town, the South African Astronomical
Observatory, the University of Oxford, the University of Manchester
and the University of Amsterdam.
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