ZTF22aabjpxh, GRB 220219B
GCN Circular 31739
Subject
ZTF22aabjpxh/AT2022cva (GRB 220219B): evidence of supernova in LBT spectra
Date
2022-03-11T14:41:55Z (4 years ago)
From
Andrea Rossi at INAF <andrea.rossi@inaf.it>
A. Rossi, E. Pian, F. Cusano, E. Maiorano, E. Palazzi (INAF-OAS) on
behalf of the CIBO collaboration, and S. Belkin (IKI, HSE) report :
We report the results of the spectroscopic follow-up observations of
ZTF22aabjpxh/AT2022cva, the afterglow of GRB 220219B (Ho et al., GCN
31619; Kim�� et al., GCN 31628; Hu et al., GCN 31639; Belkin et al., GCNs
31643, 31683; Pasham et al., GCN 31635; Beardmore et al., GCN 31644;
Tsvetkova et al., GCN 31646) at z=0.293 (Fremling et al., GCN 31629).
The optical spectra were obtained with the Multi-Object Double
Spectrographs (MODS) instrument mounted on the 2x8.4-m LBT telescope
(Mt. Graham, AZ, USA) at ~11 UT on 2021-03-07, ~16 days (i.e. ~12
rest-frame days) after the burst trigger. The spectra covers the
wavelength range 3200-10000 AA, and we obtained a total of 6 exposures
of 900s. The resulting spectrum has been corrected for Galactic
extinction (A_V = 0.025 mag).
The slit was place in order to cover both the host galaxy and the GRB
position. In addition to the host spectra, a second trace is well
visible in the 2D image of the spectrum although superimposed to the one
of the host galaxy. Its low S/N extracted spectrum shows features
similar to those exhibited by XRF-associated SN2006aj at a similar phase
(Mazzali et al. 2006, Nature, 442, 1018). This confirms the bump
observed by Belkin et al. (GCN 31736) as due to the emerging
contribution of the SN.
We acknowledge the excellent support from the LBTO, in particular B.
Rothberg and J. Williams, and from the LBT-INAF, particularly E. Marini
in obtaining these observations.
GCN Circular 31736
Subject
ZTF22aabjpxh/AT2022cva (GRB 220219B): continued optical observations, possible photometric evidence of SN
Date
2022-03-11T02:03:18Z (4 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.
GCN Circular 31720
Subject
ZTF22aabjpxh/AT2022cva: AMI-LA radio observation
Date
2022-03-09T13:44:36Z (4 years ago)
From
Lauren Rhodes at Oxford <lauren.rhodes@physics.ox.ac.uk>
L. Rhodes (Oxford/MPIfR), R. Fender (Oxford/UCT) and D.R.A. Williams (JBCA) report:
We observed ZTF22aabjpxh/AT2022cva (Ho et al., GCN 31619) with the Arcminute Microkelvin Imager - Large Array at 15.5GHz. The observation was made on 27th February 2022 at 04:42UT and lasted 4 hours. We detect a point source at the position of ZTF22aabjpxh with a flux density of 490+/-30uJy. The noise in the field is 34uJy. Subsequent observations show that the source is fading.
We thank the staff at the MRAO for scheduling these observations.
GCN Circular 31683
Subject
ZTF22aabjpxh/AT2022cva (GRB 220219B): continued optical observations, SN signature search
Date
2022-03-05T10:45:37Z (4 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.
GCN Circular 31646
Subject
Konus-Wind observation of GRB 220219B
Date
2022-02-25T05:54:26Z (4 years ago)
From
Anastasia Tsvetkova at Ioffe Institute <tsvetkova@mail.ioffe.ru>
A. Tsvetkova, D. Frederiks, A. Lysenko, A. Ridnaia, D. Svinkin,
M. Ulanov, and T. Cline on behalf of the Konus-Wind team, report:
The long-duration GRB 220219B
(IPN triangulation: Svinkin et al., GCN 31624),
consistent with the optical transient ZTF22aabjpxh/AT2022cva
reported by ZTF (Ho et al., GCN 31619),
triggered Konus-Wind at T0=34045.350 s UT (09:27:25.350).
The burst light curve consists of two broad pulses:
the first one lasts from ~T0-34 s to ~T0+13 s peaking at ~T0,
the second pulse lasts from ~T0+18 s to ~T0+45 s peaking at ~T0+20 s,
The emission is seen up to ~1 MeV.
As observed by Konus-Wind, the burst had
a fluence of the first pulse 1.21(-0.15,+0.16)x10^-5 erg/cm^2,
a fluence of the whole burst 1.76(-0.14,+0.12)x10^-5 erg/cm^2,
and a 64-ms peak energy flux, measured from T0-0.064 s,
of 1.76(-0.27,+0.52)x10^-6 erg/cm^2/s
(all in the 20 keV - 10 MeV energy range).
Since the main fraction of the first pulse was detected
before the trigger, its spectral analysis was performed using
the KW 3-channel light curve data.
Modelling its spectrum (measured from T0-33.723 s to T0+13.380 s)
by the exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep),
yields alpha = -1.86(-0.09,+4.36) and Ep = 39(-24,+27) keV.
Fitting the most intense part of the first pulse
(measured from T0-1.340 s to T0+1.604 s)
with by the exponential cutoff model yields
alpha = -1.75(-0.20,+4.25) and Ep = 61(-46,+24) keV.
The spectrum of the second emission pulse
(from T0+16.640 s to T0+49.408 s)
is well described by a simple power law (PL) with the photon PL index
of 2.60(-0.10,+0.10) and chi2/dof = 69.5/61.
Assuming the redshift z = 0.293 (Fremling et al., GCN 31629)
and a standard cosmology with H_0 = 67.3 km/s/Mpc, Omega_M = 0.315,
and Omega_Lambda = 0.685 (Planck Collaboration, 2014),
we estimate the following burst rest-frame parameters:
the isotropic energy release in the first pulse is
Eiso = 2.75(-0.34,+0.36)x10^51 erg,
the isotropic peak luminosity is Liso = 5.17(-0.79,+1.53)x10^50 erg/s;
the rest-frame peak energy of the first pulse is Epiz = 50(-31,+35) keV;
and the rest-frame peak energy of the 'peak' spectrum is
Eppz = 79(-59,+31) keV.
With these values, GRB 220219B is within 68% prediction bands for
for both 'Amati' and 'Yonetoku' relations for the sample of >300 long KW
GRBs with known redshifts (Tsvetkova et al., 2021, ApJ, 908, 83),
see http://www.ioffe.ru/LEA/GRBs/GRB220219_T34045/GRB220219B_rest_frame.pdf
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB220219_T34045/
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.
GCN Circular 31644
Subject
GRB 220219B: Swift-XRT observations
Date
2022-02-24T11:18:42Z (4 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
A.P. Beardmore (U. Leicester), M. Capalbi (INAF-IASFPA), M. Perri (SSDC
& INAF-OAR), V. D'Elia (SSDC & INAF-OAR), D.N. Burrows (PSU), J. D.
Gropp (PSU), J.A. Kennea (PSU), J.P. Osborne (U. Leicester) and P.A.
Evans (U. Leicester) report on behalf of the Swift-XRT team:
Swift-XRT has performed follow-up observations of GRB 220219B (Svinkin
et al., GCN Circ. 31624), collecting 3.5 ks of Photon Counting (PC)
mode data between T0+322.5 ks and T0+369.3 ks.
One uncatalogued X-ray source has been detected at a position
consistent with the GRB optical afterglow candidate
ZTF22aabjpxh/AT2022cva (Ho et al., GCN Circ. 31619). The X-ray source
is below the RASS limit and shows no definitive signs of fading.
Details of this source are given below:
Source 1:
RA (J2000.0): 240.91414 = 16:03:39.39
Dec (J2000.0): +31.23404 = +31:14:02.5
Error: 2.8 arcsec (radius, 90% conf. [Enhanced position])
Count-rate: 0.0250 [+0.0032, -0.0031] ct s^-1
Flux: (1.06 [+0.14, -0.13])e-12 erg cm^-2 s^-1 (observed, 0.3-10 keV)
The results of the XRT-team automatic analysis of the XRT observations,
including a position-specific upper limit calculator, are available at
https://www.swift.ac.uk/ToO_GRBs/00021481.
This circular is an official product of the Swift-XRT team.
GCN Circular 31643
Subject
ZTF22aabjpxh/AT2022cva (GRB 220219B): Mondy optical observations
Date
2022-02-23T22:36:04Z (4 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) report on behalf of GRB IKI FuN:
We observed ZTF22aabjpxh/AT2022cva discovered by ZTF (Ho et al., GCN
31619) with AZT-33IK telescope of Mondy observatory on 2022-02-21 and
2022-02-22. ZTF22aabjpxh/AT2022cva was observed also in optic (Kim et
al., GCN 31628; Hu et al., GCN 31639) and in X-ray by NICER (Pasham et
al., GCN 31635). ZTF22aabjpxh/AT2022cva is considered the likely
afterglow of GRB 220219B (Ho et al., GCN 31619; Svinkin et al., GCN 31624).
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 and preliminary
photometry of a source (afterglow+host galaxy) is following
Date UT start JD Exp. Filter OT Err. UL(3sigma)
(mid, days) (s)
2022-02-21 19:30:32 2.43966 30*120 R 19.19 0.03 22.8
2022-02-22 19:31:06 3.43936 29*120 R 19.34 0.03 22.8
The photometry is based on nearby SDSS DR12 stars
id r R(Lupton) V(Lupton)
J160337.10+311328.5 16.987 16.79 17.19
J160343.10+311452.9 18.700 18.51 18.90
Assuming the host galaxy has R = 19.7 we subtract a host galaxy flux
from a flux of the source (afterglow+host galaxy) and estimated power
law index of a light curve of the afterglow as -1.2, which is typical
for a GRB afterglow.
GCN Circular 31639
Subject
ZTF22aabjpxh/AT2022cva: 1.5m OSN optical observation
Date
2022-02-22T20:58:41Z (4 years ago)
From
Youdong HU at IAA-CSIC <huyoudong072@hotmail.com>
Y.-D. Hu, A. Sota, T.-R. Sun, A. J. Castro-Tirado, M. D. Caballero-Garcia, M. A. Castro Tirado and E. Fernandez-Garcia (IAA-CSIC), on behalf of a larger collaboration, report:
Following the detection of ZTF22aabjpxh/AT2022cva reported by ZTF (Ho et al., GCN 31619) and NICER (Pasham et al. GCNC 31635) which could be consistent with GRB220219B (Svinkin et al. GCNC 31624), images in BVRI bands were obtained at the 1.5m OSN telescope in Granada (Spain) starting on 22 Feb. 2022 at 01:49:51 UT. In single exposures (R-band, 90 s), we measure R = 19.80+-0.13 at 02:22 UT for the above-mentioned optical transient lying at the edge of the nearby galaxy at redshift z = 0.293 as reported by Gemini-North (Fremling et al. GCNC 31629). This detection is consistent with the report from Assy-Turgen (Kim et al. GCNC 31628).
We thank the staff at OSN for their excellent support.
GCN Circular 31635
Subject
ZTF22aabjpxh/AT2022cva: NICER X-ray detection is consistent with a GRB afterglow
Date
2022-02-22T17:27:01Z (4 years ago)
From
Dheeraj R. Pasham at Mass. Inst. of Technology <dheeraj@space.mit.edu>
Dheeraj Pasham (MIT), Keith Gendreau (NASA/GSFC), Elizabeth Ferrara
(NASA/GSFC), Anna Ho (UC Berkeley)
NICER observed the rapidly fading transient AT2022cva (Ho et al. GCN 31619)
for 2.4 ks starting at 2022-02-21T22:56:03. X-rays are clearly detected
above the background in the 0.3-5.0 keV band with a mean
background-subtracted count rate of 0.92+-0.02 counts/seconds. We fit the
0.3-5 keV X-ray spectrum with a redshifted powerlaw modified by neutral
absorption in Milkway and host galaxy (tbabs*ztbabs*zpow in XSPEC). Using
a Galactic nH value for tbabs (0.023e22 cm^2; HI4PI Collaboration, Bekhti
et al. 2016) and a redshift of 0.293 (Fremling et al., GCN 31619) gives a
good fit with a c-stat/degrees of freedom of 57/57. The best-fit power law
index and host column density values are 1.36(+0.14,-0.12) and <5e20 cm^-2,
respectively. The 0.3-5 keV observed flux is (2.24+-0.07)e-12 erg/s/cm^2.
This corresponds to an observed luminosity of 5.04(+0.03,-0.33)e44 erg/s at
a redshift of 0.293, which is typical for a GRB afterglow at a similar
phase.
NICER can carry out prompt follow-up observations of transients and is
planning to systematically follow up alerts from LIGO/Virgo and other X-ray
bright extra-galactic transients in the future.
NICER is a 0.2-12 keV X-ray telescope operating on the International Space
Station. The NICER mission and portions of the NICER science team
activities are funded by NASA.
GCN Circular 31634
Subject
GRB 220219B: Swift ToO observations
Date
2022-02-22T17:10:13Z (4 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
P. A. Evans (U. Leicester) reports on behalf of the Swift team:
Swift has initiated a ToO observation of the Konus-Wind GRB 220219B.
Automated analysis of the XRT data will be presented online at
https://www.swift.ac.uk/ToO_GRBs/00021481
Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. These are
not necessarily related to the Konus-Wind event. Any X-ray source
considered to be a probable afterglow candidate will be reported via a
GCN Circular after manual consideration.
Details of the XRT automated analysis methods are detailed in Evans et
al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).
This circular is an official product of the Swift-XRT team.
GCN Circular 31629
Subject
ZTF22aabjpxh/AT2022cva: GMOS-N spectroscopy
Date
2022-02-22T02:00:06Z (4 years ago)
From
Anna Ho at UC Berkeley <annayqho@berkeley.edu>
C. Fremling (Caltech), D. Perley (LJMU), A.Y.Q. Ho (UCB), report on behalf
of the ZTF collaboration
We obtained spectroscopy of ZTF22aabjpxh/AT2022cva (A.Y.Q. Ho et al.
AstroNote 2022-45) with the Gemini Multi-Object Spectrographs (GMOS-N)
mounted on the Gemini-North 8-meter telescope on Mauna Kea, under our ToO
program GN-2022A-Q-127 (PI: Ho). We obtained 2x450 second exposures using
the B600 grating and 2x450 second exposures using the R400 grating,
starting 2022-02-21 14:04 UTC.
Data reduction was performed with the Gemini iraf package, and we report
the detection of host-galaxy emission lines at z=0.293. We simultaneously
detect narrow emission from H-alpha, H-beta, NII, SII, OII and [OIII].
We thank the observers and the Gemini staff for their rapid response in
facilitating this Target of Opportunity observation.
GCN Circular 31628
Subject
ZTF22aabjpxh/AT2022cva: Assy optical observations
Date
2022-02-22T00:16:49Z (4 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
V. Kim (FAI, HSE), A. Pozanenko (IKI), M. Krugov (FAI), I. Reva (FAI),
N. Pankov (HSE, IKI), S. Belkin (IKI) report on behalf of GRB IKI FuN:
We observed ZTF22aabjpxh/AT2022cva transient (Ho et al., GCN 31619) what
is considered the likely afterglow of GRB 220219B (Ho et al., GCN 31619;
Svinkin et al., GCN 31624) with AZT-20 telescope of Assy-Turgen
observatory starting on 2022-02-21 (UT) 19:44:30.
We clearly detect the SDSS galaxy at photo_z = 0.248 (Ho et al., GCN
31619). Due to non-optimal seeing (FWHM of about 2.4") we could not
discriminate the afterglow source from the galaxy. We use aperture
photometry and preliminary photometry (AB) of a source (afterglow+host
galaxy) is following
Date UT start JD Exp. Filter OT Err. UL(3sigma)
(mid, days) (s)
2022-02-21 19:44:30 2459632.327 40*60 r' 19.20 0.03 22.1
2022-02-21 21:57:59 2459632.416 40*60 r' 19.45 0.02 22.7
The photometry is based on nearby PS1 stars
id r
J160337.10+311328.5 16.987
J160343.10+311452.9 18.700
The photometry of the the source is brighter than reported either in PS1
or SDSS DR12, and source is variable. We can conclude that the
afterglow is detected and dominate over host galaxy brightness.
GCN Circular 31624
Subject
IPN triangulation of GRB 220219B (consistent with ZTF22aabjpxh/AT2022cva)
Date
2022-02-21T18:38:56Z (4 years ago)
From
Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>
D. Svinkin, D. Frederiks, A. Ridnaia, A. Lysenko,
and T. Cline on behalf of the Konus-Wind team, and
S. Barthelmy, J. Cummings, H. Krimm, D. Palmer, and A. Tohuvavohu
on behalf of the Swift-BAT team, report:
The long-duration GRB 220219B
has been detected by Konus-Wind (KW) and Swift (BAT), so far,
at about 34045 s UT (09:27:25).
The burst was outside the coded field of view of the BAT.
We have triangulated it to a Konus-BAT annulus centered at
RA(2000)=314.433 deg (20h 57m 44s) Dec(2000)=-14.987 deg (-14d 59' 15"),
whose radius is 83.789 +/- 1.439 deg (3 sigma).
This localization may be improved.
The position of the optical transient ZTF22aabjpxh/AT2022cva
(Ho et al., GCN Circ. 31619) is inside the annulus at 0.46 deg
from its center line. The OT position is consistent with the Swift-BAT
detection, Fermi-GBM non-detection, and the KW ecliptic latitude response.
The positional and temporal coincidence of this burst with the OT
supports the conclusion that the OT is the GRB counterpart.
A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB220219_T34045/IPN
The time history and spectrum will be given in forthcoming GCN Circulars.
GCN Circular 31619
Subject
ZTF22aabjpxh/AT2022cva: ZTF Discovery of a Rapidly Fading Transient with a Likely Long-GRB Counterpart
Date
2022-02-21T04:13:18Z (4 years ago)
From
Anna Ho at UC Berkeley <annayqho@berkeley.edu>
Anna Y. Q. Ho (UCB), Daniel Perley (LJMU), Igor Andreoni (JSI), Mansi
Kasliwal (Caltech), Dmitry Svinkin (Ioffe Institute), Aaron Tohuvavohu (U.
Toronto), Harsh Kumar (IITB) on behalf of the Zwicky Transient Facility
(ZTF) collaboration:
We report the discovery of ZTF22aabjpxh (AT2022cva), a rapidly fading red
transient located at
16:03:39.35 +31:14:04.72 (J2000)
240.9139656, 31.2346451 (J2000)
first detected as part of the ZTF partnership survey.
The source was discovered on JD 2459630.0001 at r=16.59 �� 0.01 mag, which
was 0.98 days after the last non-detection (r>19.34). The transient
position is 2'' from a galaxy in SDSS with a photometric redshift of 0.25 ��
0.05. Due to the rapid rise of almost 3 magnitudes in one day, and the
possible high luminosity, we triggered follow-up photometry with the
Spectral Energy Distribution Machine (SEDM) on the 60-inch telescope at
Palomar Observatory (P60). SEDM photometry obtained the night after
discovery established a rapid fade rate of 2.25 magnitudes in 0.88 days as
well as red colors (g-r=0.41 �� 0.08, corrected for Galactic extinction).
The transient was also detected as part of the ZTF public survey that
night, and the rapid fade triggered the ZTFReST pipeline (Andreoni &
Coughlin et al. 2021).
Konus-Wind detected a long-duration GRB at UT 2022-02-19 09:27:25.350 that
is consistent with the position of AT2022cva. The GRB burst time is 2.5
hours before the first ZTF detection. The GRB was also weakly detected by
BAT. The ZTF optical position was outside the coded BAT FoV at the time of
the burst, and the observed counts are consistent with a relatively soft
burst coming from outside the BAT field of view. The Konus-BAT IPN annulus
is consistent with the position of the ZTF transient, and the association
is highly likely.
We conclude that AT2022cva is the likely afterglow to the Konus-Wind GRB.
Given the possible low redshift (z~0.3) continued photometric and
spectroscopic observations are encouraged.
Based on observations obtained with the Samuel Oschin Telescope 48-inch and
the 60-inch Telescope at the Palomar Observatory as part of the Zwicky
Transient Facility project. ZTF is supported by the National Science
Foundation under Grant No. AST-2034437 and a collaboration including
Caltech, IPAC, the Weizmann Institute for Science, the Oskar Klein Center
at Stockholm University, the University of Maryland, Deutsches
Elektronen-Synchrotron and Humboldt University, the TANGO Consortium of
Taiwan, the University of Wisconsin at Milwaukee, Trinity College Dublin,
Lawrence Livermore National Laboratories, IN2P3, University of Warwick,
Ruhr University Bochum and Northwestern University. Operations are
conducted by COO, IPAC, and UW.
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Anna Ho