TITLE:   GCN CIRCULAR
NUMBER:  30320
SUBJECT: GRB210619B: optical afterglow detection from Konkoly Observatory
DATE:    21/06/25 21:54:22 GMT
FROM:    Jozsef Vinko at Konkoly Observator  <vinko@konkoly.hu>

J. Vinko, L. Kriskovics, A. Pal, R. Szakats, K. Vida, Zs. Szabo, R. Konyves-Toth, M. Krezinger and K. Sarneczky (Konkoly Observatory, Hungary) report:

We observed the field of GRB210619B
(D'Avanzo et al.,GCN #30261, #30288, #30289; Jelinek et al., GCN #30263, #30281;
Lipunov et al., GCN #30259; Zhao et al., GCN #30261; Kong et al.,
GCN #30265; Axelsson et al., #GCN 30270; de Ugarte Postigo et al.,
GCN #30272; Zheng et al., GCN #30273; Blazek et al., GCN #30274;
Kann et al., GCN #30275; Svinkin et al., GCN #30276; Xin et al.,
GCN #30277; Perley et al., GCN #30271, Shrestha et al., GCN #30280,
Kumar et al. GCN #30286; Cunningham et al., GCN #30290; Romanov,
GCN #30291; Hu et al., GCN #30293; Zhu et al., GCN #30294;
Belkin et al., GCN #30299; Atteia, GCN #30301, Minaev et al.,
GCN #30304; Romanov & Lane, GCN #30305; Karpov et al., GCN #30308;
Moskvitin & Maslennikova, GCN #30309; Marisaldi et al., GCN #30315)
with the RC80 robotic telescope at Piszkesteto Station of Konkoly
Observatory on 2021 June 22 starting at 22:46:41.5 UT. A series of 5x300 sec
frames were collected through Sloan r'- and i' bands. The optical afterglow
was detected with the following magnitudes calibrated via nearby PS1 stars:

Date         UT-middle   t-T0(hr)  Exp(s)   r'(mag)           i'(mag)
2021-06-22   23:07:16    71.13     5x300    21.454 +/-0.333   20.089 +/-0.280

Follow-up observations on 2021-06-23 starting at 21:34:37.7 UT (3.90 days post-trigger)
resulted in no detection down to limiting magnitudes of r'=22.14 and i'=21.98 mag.