[vsnet-grb-info 27432] GRB 210217A: Liverpool Telescope First Hour Observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  29535
SUBJECT: GRB 210217A: Liverpool Telescope First Hour Observations
DATE:    21/02/18 22:17:33 GMT
FROM:    Manisha Shrestha at Liverpool John Moores U  <m.shrestha at ljmu.ac.uk>

M. Shrestha (Liverpool JMU), R. Smith (LJMU) , A. Melandri (INAF), I.A. Steele (LJMU), S. Kobayashi (LJMU), C. Mundell (Univ. Bath), A. Gomboc (Univ. Nova Gorica), C. Guidorzi (Univ. Ferrara)  report on behalf of a wider collaboration:



We observed the field of Swift GRB 210217A (GCN 29521) with the 2.0m Liverpool Telescope (LT), La Palma on 2021 Feb 17 starting at 23:28:51.056  UT

using the IO:O optical camera in the r’, i’, and z’ bands.  Data were calibrated with respect to nearby APASS secondary standard stars for r’ and i’ bands

and SDSS secondary standard stars for z’ band. We confirm the optical counterpart reported by Swift UVOT and NEXT (GCN 29523).



At T=194 seconds after the BAT trigger time, we measure r’ = 18.51 +/- 0.3 mag which is close to 18.6 +/- 0.2 mag detected by NEXT team (GCN 29523).

The r’ band light curve made with IO:O observations show a power law decay over the first hour in flux vs time with alpha = 0.48.

At T = 690 seconds after the BAT trigger time, we measure i’ = 18.77 +/- 0.1 mag and at T = 868 seconds after the trigger we measure z’ = 18.67 +/-0.1 mag.




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