[vsnet-grb-info 28103] GRB 210610B: Zwicky Transient Facility afterglow detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  30206
SUBJECT: GRB 210610B: Zwicky Transient Facility afterglow detection
DATE:    21/06/11 18:11:12 GMT
FROM:    Daniel Perley at Liverpool JMU  <d.a.perley at ljmu.ac.uk>

D. A. Perley (LJMU), Y. Yao (Caltech), A. Y. Q. Ho (UC Berkeley), M. 
Bulla (Stockholm/OKC), I. Andreoni (Caltech), M. Coughlin (U. 
Minnesota), and E. Kool (Stockholm/OKC) report:

The Zwicky Transient Facility (ZTF; ATel #11266) observed the location 
of GRB 210610B (Page et al., GCN 30170) during the night of 2021-06-11 
UT as part of the regular operations of the ZTF high-cadence partnership 
survey.  Four separate observations of the field (ZTF field ID 533) were 
obtained between 2021-06-11 05:34:44 and 2021-06-11 08:38:29, two each 
in g-band and r-band.

The associated optical transient (e.g., Page et al., GCN 30170; Kumar et 
al., GCN 30174) was automatically identified by the ZTF image 
subtraction pipeline and assigned the identifier ZTF21abfmpwn.  The 
source was independently flagged as a fast transient candidate by both 
the ZTF fast-transient filter pipeline developed by A. Ho and Y. Yao 
(Perley et al. 2021, arXiv:2103.01968) and by the ZTFReST pipeline 
(Andreoni et al. 2021, arXiv:2104.06352), on the basis of its rapid 
evolution over the course of the night and coincidence with a galaxy in 
Pan-STARRS and Legacy Survey reference imaging.

We provide the following photometry:

MJD           t_GRB(d)     filter   magnitude
59376.2324    0.4050       g        18.49 +/- 0.10
59376.2751    0.4477       r        18.29 +/- 0.07
59376.3206    0.4932       r        18.44 +/- 0.07
59376.3600    0.5326       g        18.81 +/- 0.07

Photometry is as provided by the ZTF alert packets and is 
reference-subtracted.  Magnitudes are AB and are not corrected for 
Galactic extinction.

ZTF is supported by the National Science Foundation under Grant No. 
AST-2034437 and a collaboration including Caltech, IPAC, the Weizmann 
Institute for Science, the Oskar Klein Center at Stockholm University, 
the University of Maryland, Deutsches Elektronen-Synchrotron and 
Humboldt University, the TANGO Consortium of Taiwan, the University of 
Wisconsin at Milwaukee, Trinity College Dublin, Lawrence Livermore 
National Laboratories, and IN2P3, France. Operations are conducted by 
COO, IPAC, and UW.

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