GRB 220426A
GCN Circular 31950
Subject
GRB 220426A: BALROG localization (Fermi Trigger 672648596/ GRB 220426285)
Date
2022-04-26T07:14:08Z (3 years ago)
From
Jochen Greiner at MPE,Garching <jcg@mpe.mpg.de>
B. Biltzinger, F. Kunzweiler, F. Berlato, J. Burgess & J. Greiner (all MPE Garching) report:
The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger 672648596
at 06:49:51 on 26 April 2022 were automatically fitted for spectrum
and sky location with BALROG (Burgess et al. 2018, MNRAS 476, 1427;
Berlato et al. 2019, ApJ 873, 60).
The best-fit position (1 sigma statistical errors) is:
RA(2000.0) = 339.6+/-0.3 deg
Decl.(2000.0) = -24.0+/-0.3 deg
We estimate an additional systematic error of 2 deg.
Further details are available at:
https://grb.mpe.mpg.de/grb/GRB220426285/
The Healpix map can be downloaded from:
https://grb.mpe.mpg.de/grb/GRB220426285/healpix
The location parameters are available as JSON at:
https://grb.mpe.mpg.de/grb/GRB220426285/json
GCN Circular 31954
Subject
GRB 220426A: Swift/BAT-GUANO detection outside the coded FOV
Date
2022-04-26T19:00:41Z (3 years ago)
From
Aaron Tohuvavohu at U Toronto <aaron.tohu@gmail.com>
Aaron Tohuvavohu (U Toronto), Gayathri Raman (PSU), James DeLaunay
(UAlabama), Jamie A. Kennea (PSU), report:
Swift/BAT did not localize GRB 220426A onboard (T0:
2022-04-26T06:49:51 UTC, Fermi/GBM trig #672648596, INTEGRAL/SPI-ACS
trig #9876).
The Fermi and INTEGRAL notices, distributed in near real-time,
triggered the Swift Mission Operations Center operated Gamma-ray
Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al.
2020, ApJ, 900, 1).
Upon trigger by this notice, GUANO sent a command to the Swift Burst
Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from
[-50,+150] seconds around the time of the burst. All the requested
event mode data was delivered to the ground.
The BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu,
arXiv:2111.01769), detects the burst with a sqrt(TS) of 169 in a 4.096
s analysis time bin.
The burst episode as seen by BAT is ~6s long.
NITRATES results strongly indicate a burst coming from outside the
coded FoV, with DeltaLLHOut of -1550, consistent with the Fermi/GBM
BALROG localization (GCN 31950).
See Section 9.1 and Figure 20 in the NITRATES paper for brief
descriptions and interpretation of sqrt(TS), DeltaLLHPeak, and
DeltaLLHOut.
GUANO is a fully autonomous, extremely low latency, spacecraft
commanding pipeline designed for targeted recovery of BAT event mode
data around the times of compelling astrophysical events to enable
more sensitive GRB searches.
A live reporting of Swift/BAT event data recovered by GUANO can be
found at: https://www.swift.psu.edu/guano/
GCN Circular 31955
Subject
GRB 220426A: Fermi GBM detection
Date
2022-04-26T19:42:53Z (3 years ago)
From
Christian Malacaria at NASA-MSFC/USRA <cmalacaria@usra.edu>
C. Malacaria (USRA) and C. Meegan (UAH) report on behalf of the Fermi GBM Team:
At 06:49:51.23 UT on 26 April 2022, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 220426A (trigger 672648596 / 220426285).
The on-ground calculated location, using the GBM trigger data,
is RA = 335.8, DEC = -20.5 (J2000 degrees, equivalent
to 22h 23m, -20d 30'), with an uncertainty of 1.0 degrees
(radius, 1-sigma containment, statistical only; there is additionally a
systematic error which we have characterized as a core-plus-tail model,
with 90% of GRBs having a 3.7 deg error and a small tail suffering a
larger than 10 deg systematic error. [Connaughton et al. 2015, ApJS, 216, 32] ).
The angle from the Fermi LAT boresight at the GBM trigger time is 76 degrees.
The GBM light curve consists of a double pulse on top of a broader peak
with a duration (T90) of about 6 s (50-300 keV).
The time-averaged spectrum from T0+0.002 s to T0+9.856 s is
best fit by a Band function with Epeak = 146.3 +/- 0.9 keV,
alpha = -0.05 +/- 0.01, and beta = -3.08 +/- 0.04 .
The event fluence (10-1000 keV) in this time interval is
(1.084+/-0.005)E-04 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+3.9 s in the 10-1000 keV band
is 180.7 +/- 0.9 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html
For Fermi GBM data and info, please visit the official Fermi GBM Support Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/
GCN Circular 31956
Subject
Fermi GRB 220426A: Global MASTER-Net observations report
Date
2022-04-27T04:30:33Z (3 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
V. Lipunov, V.Kornilov, E.Gorbovskoy, K.Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, D. Vlasenko,
G.Antipov, D.Zimnukhov, V.Senik, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D.Cheryasov, Ya.Kechin
(Lomonosov Moscow State University, SAI, Physics Department),
R. Podesta, C.Lopez, F. Podesta, C.Francile
(Observatorio Astronomico Felix Aguilar OAFA),
R. Rebolo, M. Serra
(The Instituto de Astrofisica de Canarias),
D. Buckley
(South African Astronomical Observatory),
O.A. Gres, N.M. Budnev
(Irkutsk State University, API),
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez
(INAOE, Guillermo Haro Astrophysics Observatory),
A. Tlatov, D. Dormidontov
(Kislovodsk Solar Station of the Pulkovo Observatory),
A. Gabovich, V.Yurkov
(Blagoveschensk Educational State University)
MASTER-OAGH robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Mexico (OAGH National Institute for Astrophysics, Optics and Electronics) started inspect of the Fermi GRB 220426A ( C. Malacaria et al., GCN 31955) errorbox 13914 sec after notice time and 13944 sec after trigger time at 2022-04-26 10:42:15 UT, with upper limit up to 18.2 mag. The observations began at zenith distance = 87 deg. The sun altitude is -23.6 deg.
The galactic latitude b = -57 deg., longitude l = 33 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=1954577
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
13974 | 2022-04-26 10:42:15 | MASTER-OAGH | (22h 26m 58.35s , -22d 47m 13.6s) | C | 60 | 14.0 |
13974 | 2022-04-26 10:42:15 | MASTER-OAGH | (22h 18m 46.43s , -23d 14m 51.0s) | C | 60 | 14.2 |
14195 | 2022-04-26 10:45:55 | MASTER-OAGH | (22h 27m 04.78s , -22d 46m 50.5s) | C | 60 | 14.4 |
14195 | 2022-04-26 10:45:55 | MASTER-OAGH | (22h 18m 53.88s , -23d 14m 54.4s) | C | 60 | 14.3 |
14416 | 2022-04-26 10:49:36 | MASTER-OAGH | (22h 27m 01.55s , -22d 45m 08.6s) | C | 60 | 14.7 |
14416 | 2022-04-26 10:49:36 | MASTER-OAGH | (22h 18m 52.02s , -23d 13m 27.6s) | C | 60 | 14.4 |
14638 | 2022-04-26 10:53:19 | MASTER-OAGH | (22h 27m 01.61s , -22d 46m 16.7s) | C | 60 | 15.0 |
14638 | 2022-04-26 10:53:19 | MASTER-OAGH | (22h 18m 53.98s , -23d 13m 57.4s) | C | 60 | 14.4 |
15069 | 2022-04-26 11:00:29 | MASTER-OAGH | (22h 26m 59.82s , -22d 44m 34.8s) | C | 60 | 13.5 |
15069 | 2022-04-26 11:00:29 | MASTER-OAGH | (22h 18m 47.92s , -23d 13m 32.3s) | C | 60 | 15.3 |
15399 | 2022-04-26 11:05:59 | MASTER-OAGH | (22h 26m 59.62s , -22d 44m 54.8s) | C | 60 | 16.0 |
15399 | 2022-04-26 11:05:59 | MASTER-OAGH | (22h 18m 51.90s , -23d 13m 10.4s) | C | 60 | 15.5 |
15621 | 2022-04-26 11:09:42 | MASTER-OAGH | (22h 27m 05.08s , -22d 45m 53.1s) | C | 60 | 15.9 |
15621 | 2022-04-26 11:09:42 | MASTER-OAGH | (22h 18m 57.09s , -23d 14m 19.4s) | C | 60 | 15.3 |
15843 | 2022-04-26 11:13:23 | MASTER-OAGH | (22h 27m 00.35s , -22d 46m 49.8s) | C | 60 | 16.0 |
15843 | 2022-04-26 11:13:23 | MASTER-OAGH | (22h 18m 53.16s , -23d 14m 44.6s) | C | 60 | 15.2 |
16335 | 2022-04-26 11:20:36 | MASTER-OAGH | (22h 27m 03.19s , -22d 44m 58.7s) | C | 180 | 16.9 |
16335 | 2022-04-26 11:20:36 | MASTER-OAGH | (22h 18m 54.54s , -23d 13m 07.3s) | C | 180 | 16.1 |
16677 | 2022-04-26 11:26:18 | MASTER-OAGH | (22h 27m 03.75s , -22d 46m 34.8s) | C | 180 | 18.1 |
16677 | 2022-04-26 11:26:18 | MASTER-OAGH | (22h 18m 54.96s , -23d 14m 42.0s) | C | 180 | 18.0 |
17018 | 2022-04-26 11:31:59 | MASTER-OAGH | (22h 27m 07.01s , -22d 45m 21.0s) | C | 180 | 18.2 |
17018 | 2022-04-26 11:31:59 | MASTER-OAGH | (22h 18m 58.09s , -23d 13m 28.3s) | C | 180 | 18.1 |
17360 | 2022-04-26 11:37:41 | MASTER-OAGH | (22h 27m 01.27s , -22d 45m 58.8s) | C | 180 | 18.2 |
17360 | 2022-04-26 11:37:41 | MASTER-OAGH | (22h 18m 52.06s , -23d 14m 06.9s) | C | 180 | 18.0 |
17703 | 2022-04-26 11:43:23 | MASTER-OAGH | (22h 27m 02.75s , -22d 44m 59.6s) | C | 180 | 17.6 |
17703 | 2022-04-26 11:43:23 | MASTER-OAGH | (22h 18m 53.37s , -23d 13m 07.8s) | C | 180 | 17.6 |
18045 | 2022-04-26 11:49:05 | MASTER-OAGH | (22h 27m 08.28s , -22d 46m 00.6s) | C | 180 | 16.9 |
18045 | 2022-04-26 11:49:05 | MASTER-OAGH | (22h 18m 58.55s , -23d 14m 08.2s) | C | 180 | 16.8 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
GCN Circular 31958
Subject
IPN triangulation of GRB 220426A
Date
2022-04-27T19:30:24Z (3 years ago)
From
Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>
A.S. Kozyrev, D.V. Golovin, M.L. Litvak, I.G. Mitrofanov, and A.B. Sanin
on behalf of the HEND/Mars-Odyssey team,
D. Svinkin, D. Frederiks, A. Ridnaia, A. Lysenko,
and T. Cline on behalf of the Konus-Wind team,
A. Goldstein, M. S. Briggs, and C. Wilson-Hodge
on behalf of the Fermi GBM team,
E. Bozzo and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,
S. Barthelmy, J. Cummings, H. Krimm, D. Palmer, and A. Tohuvavohu
on behalf of the Swift-BAT team,
and
W. Boynton, C. Fellows, K. Harshman, H. Enos, R. Starr,
and A.S. Gardner on on behalf of the GRS-Odyssey GRB team,
report:
The very bright, long-duration GRB 220426A
(BALROG localization: Biltzinger et al., GCN Circ. 31950;
Swift/BAT-GUANO detection: Tohuvavohu et al., GCN Circ. 31954;
Fermi-GBM detection: Malacaria and Meegan, GCN Circ. 31955)
has been detected by Fermi (GBM trigger 672648596), INTEGRAL (SPI-ACS),
Swift (BAT), Konus-Wind, and Mars-Odyssey (HEND), so far,
at about 24591 s UT (06:49:51).
The burst was outside the coded field of view of the BAT.
We have triangulated it to a preliminary, 3 sigma error box
whose coordinates are:
---------------------------------------------
RA(2000), deg Dec(2000), deg
---------------------------------------------
Center:
338.692 (22h 34m 46s) -22.994 (-22d 59' 38")
Corners:
337.871 (22h 31m 29s) -22.760 (-22d 45' 38")
337.994 (22h 31m 59s) -23.010 (-23d 00' 37")
339.494 (22h 37m 59s) -23.176 (-23d 10' 35")
339.374 (22h 37m 30s) -22.943 (-22d 56' 35")
---------------------------------------------
The error box area is 1131 sq. arcmin, and its maximum
dimension is 1.6 deg (the minimum one is 13.6 arcmin).
The Sun distance was 64 deg.
This box may be improved.
The IPN localization is consistent with, but reduces the area of, the
Fermi GBM Final Real-time position (GCN Circ. 31955) and BALROG
(GCN 31950) localizations.
A triangulation map and HEALPix FITS file are posted at
http://www.ioffe.ru/LEA/GRBs/GRB220426_T24589/IPN/
Swift ToO has been approved.
The Konus-Wind time history and spectrum will be given in a forthcoming
GCN Circular.
GCN Circular 31959
Subject
Konus-Wind detection of GRB 220426A
Date
2022-04-27T20:15:34Z (3 years ago)
From
Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru>
D. Frederiks, A.Lysenko, A. Ridnaia, D. Svinkin,
A. Tsvetkova, M. Ulanov, and T. Cline,
on behalf of the Konus-Wind team, report:
The long GRB 220426A (BALROG localization: Biltzinger et al., GCN Circ.
31950;
Swift/BAT-GUANO detection outside the coded FOV: Tohuvavohu et al.,
GCN Circ. 31954;
Fermi-GBM detection: Malacaria & Meegan, GCN Circ. 31955;
IPN localization: Kozyrev et al., GCN 31958)
triggered Konus-Wind (KW) at T0=24589.598 s UT (06:49:49.598).
The burst light curve shows a bright, double-peaked pulse
which starts at ~T0-0.5 s and has a total duration of ~11 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/GRB220426_T24589/
As observed by Konus-Wind, the burst had
a fluence of (9.2 �� 0.2)x10^-5 erg/cm^2 and
a 64-ms peak energy flux, measured from T0 + 2.432 s,
of (2.9 �� 0.2)x10^-5 erg/cm^2/s (both in the 20 keV - 10 MeV energy range).
The time-integrated spectrum (measured from T0 to T0+13.312 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.29 (-0.07,+0.07),
the high energy photon index beta = -4.00 (-0.71,+0.32),
the peak energy Ep = 158 (-3,+4) keV,
chi2 = 112/97 dof.
The spectrum near the peak count rate (measured from T0+2.304 s
to T0+2.560 s) is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = 0.10 (-0.17,+0.21),
the high energy photon index beta = -5.6 (-4.3,+1.7),
the peak energy Ep = 227 (-15,+13) keV,
chi2 = 47/38 dof.
All the quoted errors are estimated at the 90% confidence level.
All the presented results are preliminary.
GCN Circular 31961
Subject
GRB 220426A: Tiled Swift observations
Date
2022-04-28T03:40:03Z (3 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 series of observations, tiled on the sky, of the
IPN GRB 220426A. Automated analysis of the XRT data will
be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00104
Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. The probability of finding
serendipitous sources, unrelated to the IPN event is high: 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 31966
Subject
GRB 220426A: Swift-XRT and UVOT observations
Date
2022-04-28T17:31:31Z (3 years ago)
From
Valerio D'Elia at ASDC <valerio.delia@ssdc.asi.it>
V. D���Elia (ASI-SSDC & INAF-OAR) and M. H. Siegel (PSU)
report on behalf of the Swift team:
Swift has performed follow-up observations of the Fermi/GBM-detected burst GRB 220426A (GCN Circ. 31950, 31955), which was also detected by Swift/BAT-GUANO (GCN Circ. 31954), Konus-Wind (GCN Circ. 31959), INTEGRAL/SPI-ACS, and HEND/Mars-Odyssey (GCN Circ. 31958).
The XRT observations consist of three tiles of 1 ks each, to cover the GRB error region. The data were acquired between 45 and 47 hours after the burst and are entirely in PC mode.
One bright, uncatalogued X-ray source has been detected:
Source 1:
RA (J2000.0): 22h 32m 34.33s
Dec (J2000.0): -22�� 57��� 01.0���
Error: 3.7 arcsec (radius, 90% conf.)
Count-rate: (1.4 +/- 0.5)e-2 ct s^-1
Distance: 3.2 arcmin from the IPN position
Flux: (4.1 +/- 1.4)e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)
Nevertheless, we note that at the XRT position the RASS PSPC 3 sigma upper limit is 0.05 cts/s (XRT equivalent count-rate).
The UVOT took images of 616s each on the three XRT tiles with the white filter 160-170 ks after the trigger. We identify one source at 1.9��� from the XRT coordinates of Source 1, with a white magnitude of 18.01.
The UVOT position is:
RA (J2000) = 22:32:34.39 = 338.14330 (deg.)
Dec (J2000) = -22:57:02.7 = 22.95074 (deg.)
with an estimated uncertainty of 0.5 arc sec. (radius, 90% confidence).
However, we note that this is a known source in the DSS and is therefore unlikely to be the afterglow. No other sources are detected to a limiting magnitude in the white filter of 20.8.
More Swift observations are planned in the next days to assess for variability
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/xrt_products/TILED_GRB00104/<https://eur02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.swift.ac.uk%2Fxrt_products%2FTILED_GRB00104%2F&data=05%7C01%7Cvalerio.delia%40ssdc.asi.it%7Cbbf1b046abbf47f102b008da29348927%7Ccbfc58d4e60f468d8fe490676de085f7%7C0%7C0%7C637867602862749464%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=rivAVi0hBq7OV9vDQ4K1Xb1mbfcuxK9etLjffE3p1UI%3D&reserved=0>.
This circular is an official product of the Swift team.