GRB 220107A
GCN Circular 31431
Subject
GRB 220107A: SAO RAS optical observations
Date
2022-01-11T05:08:48Z (4 years ago)
From
Moskvitin Alexander at SAO RAS <mosk@sao.ru>
A. Moskvitin (SAO), on behalf of larger GRB follow-up team report:
We observed the field of GRB 220107A (The Fermi GBM team, GCN 31399;
Kunzweiler et al. GCN 31400; DeLaunay et al. GCN 31402; Suresh et al.,
GCN 31408; Ridnaia et al., GCN 31429) with the SAO RAS 1-m telescope
Zeiss-1000 + CCD-photometer. Two series of images in Rc band
were obtained: the 1st under moderate weather conditions
and the 2nd with relatively clear sky.
The OT (Hosokawa et al. GCN 31413; Siegel GCN 31415; Zhu et al.
GCN 31416; Pankov et al., GCN 31419; Moskvitin et al., GCN 31422;
Castro-Tirado et al., GCN 31423, Moskvitin & Medvedev, GCN 31426)
is clearly visible in the stacked frames. Preliminary photometry
of the afterglow is as follows (based on nearby SDSS-DR12 stars
mentioned in GCNs 31422, 31426).
UT start -- UT end T_mid-T0, d Exp., s R_mag +/- err series
Jan. 10 Jan. 11
23:22:13 -- 02:06:39 3.41592 23 x 300 21.69 +/- 0.10 1st
Jan. 11 Jan. 11
02:49:39 -- 03:30:10 3.51694 8 x 300 22.03 +/- 0.09 2nd
GCN Circular 31429
Subject
Konus-Wind detection of GRB 220107A
Date
2022-01-10T19:41:10Z (4 years ago)
From
Anna Ridnaia at Ioffe Institute <ridnaia@mail.ioffe.ru>
A. Ridnaia, D. Frederiks, A. Lysenko, D. Svinkin,
A. Tsvetkova, M. Ulanov, and T. Cline
on behalf of the Konus-Wind team, report:
The long-duration GRB 220107A
(Fermi/GBM trigger #663259536: Fermi GBM Team, GCN 31399;
Kunzweiler et al., GCN 31400; Veres and Meegan, GCN 31406;
Swift/BAT-GUANO localization: DeLaunay et al., GCN 31402;
AstroSat CZTI detection: Suresh et al., GCN 31408)
triggered Konus-Wind at T0=53142.427 s UT (14:45:42.427).
The burst light curve shows a multipeaked structure
started at ~T0-7.6 s with a total duration of ~110.8 s.
The emission is seen up to ~2 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB220107_T53142/
As observed by Konus-Wind, the burst
had a fluence of 5.48(-0.30,+0.34)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+81.344 s,
of 8.18(-1.55,+1.54)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the burst
(measured from T0 to T0+105.984 s)
is best fit in the 20 keV - 2 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with alpha = -1.02(-0.11,+0.12)
and Ep = 247(-24,+30) keV (chi2 = 53/61 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.4
(chi2 = 53/60 dof).
The spectrum near the maximum count rate
(measured from T0+73.984 to T0+89.600 s)
is best fit in the 20 keV - 2 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.86(-0.11,+0.12),
the high energy photon index beta = -2.91(-1.53,+0.32),
the peak energy Ep = 186(-15,+17) keV
(chi2 = 46/60 dof).
Assuming the redshift z=1.246 (Castro-Tirado et al., GCN 31423)
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 isotropic energy release E_iso to (2.3 �� 0.1)x10^53 erg,
the isotropic luminosity L_iso to (7.8 �� 1.5)x10^52 erg/s,
the rest-frame peak energy of the time-integrated spectrum Epi,z to (555 ��
67) keV,
and the rest-frame peak energy of the 'peak' spectrum Epp,z to (418 �� 38)
keV.
With these values, GRB 220107A 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/GRB220107_T53142/GRB220107A_rest_frame.pdf
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.
GCN Circular 31426
Subject
GRB 220107A: further SAO RAS optical observations
Date
2022-01-09T23:40:53Z (4 years ago)
From
Moskvitin Alexander at SAO RAS <mosk@sao.ru>