GCN Circular 31683
Subject
ZTF22aabjpxh/AT2022cva (GRB 220219B): continued optical observations, SN signature search
Date
2022-03-05T10:45:37Z (2 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
S. Belkin (IKI, HSE), A. Pozanenko (IKI), N. Pankov (HSE), E. Klunko
(ISTP), I. Reva (FAI), V. Kim (FAI) report on behalf of GRB IKI FuN:
We are continuing observations of ZTF22aabjpxh/AT2022cva discovered by
ZTF (Ho et al., GCN 31619) with AZT-33IK telescope of Mondy observatory
and Zeiss-1000 on 2022-02-21 between 2022-02-23 and 2022-03-04, i.e. upt
13.4 days after GRB 220219B trigger. ZTF22aabjpxh/AT2022cva was observed
in optic (Kim et al., GCN 31628; Hu et al., GCN 31639) and in X-ray by
NICER (Pasham et al., GCN 31635) and XRT/Swift (Beardmore et al., GCN
31644). ZTF22aabjpxh/AT2022cva is considered the likely afterglow of GRB
220219B (Ho et al., GCN 31619; Svinkin et al., GCN 31624; Tsvetkova et
al., GCN 31646).
We clearly detect the SDSS galaxy at z=0.293 (Fremling et al., GCN
31629). Due to non-optimal seeing we could not discriminate the
afterglow from the galaxy. We use aperture photometry of a source
(afterglow + host galaxy). Based on our preliminary photometry we plot
a light curve of the source, see upper panel of the Figure in
http://grb.rssi.ru/GRB220219B/GRB220219B_AT2022cva_LC.png
To estimate power law index of the afterglow we fit our photometric data
by a single power law + constant host galaxy flux. The host galaxy fit
is R = 19.68+/-0.05 and PL index alpha = -1.75+/-0.4. The light curve of
the afterglow after subtraction of a flux of the host is presented at
bottom panel of the Figure in
http://grb.rssi.ru/GRB220219B/GRB220219B_AT2022cva_LC.png
Power Law index is broadly compatible with the index of -1.6 obtained in
XRT observations up to ~8 days, see XRT light curve at
https://www.swift.ac.uk/xrt_live_cat/00021481/
We may conclude the source ZTF22aabjpxh/AT2022cva is the optical
afterglow of GRB 220219B.
Since the redshift of GRB 220219B (ZTF22aabjpxh/AT2022cva) is z=0.293
(Fremling et al., GCN 31629) we are searching for a supernova signature.
Based on the Figure referenced above we still don't see any conclusive
evidence for the existence of SN.
We urge further multicolour observations to confirm/search for SN
associated with GRB 220219B.