GCN Circular 31736
Subject
ZTF22aabjpxh/AT2022cva (GRB 220219B): continued optical observations, possible photometric evidence of SN
Date
2022-03-11T02:03:18Z (2 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
S. Belkin (IKI, HSE), A. Pozanenko (IKI), E. Klunko (ISTP), A.
Moskvitin (SAO RAS), R. Ya. Inasaridze (AbAO), N. Pankov (HSE), V. Kim
(HSE, FAI), I. Reva (FAI), on behalf of GRB IKI FuN, and A. Rossi
(INAF-OAS) report:
We are continuing observations of ZTF22aabjpxh/AT2022cva discovered by
ZTF (Ho et al., GCN 31619) with AZT-33IK telescope of Mondy observatory,
AS-32 telescope of Abastumani observatory, and Zeiss-1000 telescope of
SAO RAS between 2022-02-24 and 2022-03-09. ZTF22aabjpxh/AT2022cva was
observed in optic (Kim et al., GCN 31628; Hu et al., GCN 31639; Belkin
et al., GCNs 31643, 31683) and in X-ray by NICER (Pasham et al., GCN
31635) and XRT/Swift (Beardmore et al., GCN 31644).
ZTF22aabjpxh/AT2022cva is considered an afterglow of GRB 220219B (Ho et
al., GCN 31619; Svinkin et al., GCN 31624; Tsvetkova et al., GCN 31646;
Belkin et al., GCN 31683).
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 an 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 between start of our
observations and up to 13.4 days after GRB 220219B trigger. The host
galaxy fit is R = 19.68+/-0.05 and PL index alpha = -1.75+/-0.4 (Belkin
et al., GCN 31683). The light curve of the afterglow after subtraction
of a flux of the host is presented at the bottom panel of the Figure in
http://grb.rssi.ru/GRB220219B/GRB220219B_AT2022cva_LC.png
Starting on ~15.5 days the light curve is rising above afterglow
approximation by the single power law and we consider it as a possible
evidence of rising supernova.
We urge further spectroscopic and multicolour observations to confirm
for SN associated with GRB 220219B.