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GCN Circular 30263

GRB 210619B: Ondrejov D50 detection
2021-06-20T02:47:13Z (3 years ago)
Martin Jelinek at Astro.Inst-AVCR,Ondrejov <>
M. Jelinek, J. Strobl, R. Hudec, C. Polasek (ASU CAS Ondrejov)

We observed the position of the bright GRB 210420B (D'Avanzo et al., GCN
30261) with the D50 telescope of the Astronomical Institute Ondrejov, near
Prague, Czech Republic. We performed a series of unfiltered exposures
starting 23:59:53 UT, between 28 s and 2 h after the trigger.

The optical afterglow (Lipunov et al., GCNC30259 & 30262) is clearly
detected in single images. We can confirm a decaying nature of the object -
the afterglow faded to r'(AB)~17.7 mag during the course of our
observations, which were ended by twillight 2.0h after the trigger. The
alpha decay by the  end of observations was ~0.6, indicating a possible
plateau phase.
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