TITLE:   GCN CIRCULAR
NUMBER:  27166
SUBJECT: GRB 200219C: OAJ afterglow confirmation
DATE:    20/02/21 20:03:17 GMT
FROM:    Alexander Kann at IAA-CSIC  <kann@iaa.es>

M. Blazek, D. A. Kann (both HETH/IAA-CSIC), A. de Ugarte Postigo 
(HETH/IAA-CSIC, DARK/NBI), C. C. Thoene, J. F. Agui Fernandez (both 
HETH/IAA-CSIC), N. Maicas, and J. L. Lamadrid (both CEFCA) report:

We observed the position of the Fermi GBM/LAT GRB 200219C (Fermi GBM 
team, GCN #27145, Hamburg et al., GCN #27155, Dirirsa et al., GCN 
#27151) with the Javalambre Observatory OAJ 80cm telescope in g'r'i'z', 
obtaining 3 x 300 s exposures in g'r' each, and 5 x 180 s exposures in 
i'z' each. Observations started on 2020-02-21, 03:17:55 UT. No 
observations were obtained the night before as the LAT position came 
only after twilight had started.

In the stacked r' image (midtime 1.14375 days after the GRB), we clearly 
detect a source within the enhanced XRT error circle (Burrows et al., 
GCN #27157) for which we measure r'(AB) = 22.11 ± 0.13 mag against 
PanSTARRS field stars.

We note this implies a decay compared with the afterglow discovery by 
Reva et al. (GCN #27162) who find R ~ 21.72 ± 0.15 mag (AB) about six 
hours earlier. It is still brighter than the PanSTARRS host galaxy 
magnitude given by Xu et al. (GCN #27161) at r' = 22.70 ± 0.15 mag.

The relatively bright host galaxy may be indicative of a low-redshift 
event. As the source is improving in visibility and will be observable 
for several months to come, a search for associated supernova emission 
may be worthwhile. Spectroscopy is encouraged.