GRB 201218A
GCN Circular 29095
Subject
Konus-Wind observation of GRB 201218A
Date
2020-12-20T14:24:35Z (5 years ago)
From
Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>
D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks,
M. Ulanov, A. Tsvetkova, A. Lysenko, A. Ridnaia, and T. Cline
on behalf of the Konus-Wind team, report:
The long-duration, very bright GRB 201218A
(Fermi-GBM detection: The Fermi GBM team, GCN Circ. 29081;
BALROG localization: Biltzinger et al., GCN Circ. 29083;
IPN triangulation: Hurley et al., GCN Circ. 29090)
triggered Konus-Wind at T0=15253.184 s UT (04:14:13.184).
The burst light curve shows a multipeaked structure
which starts at ~T0-17 s and has a total duration of ~55 s,
followed by a weak tail seen up to ~T0+120 s.
The emission is seen up to ~5 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB201218_T15255
As observed by Konus-Wind, the burst
had a fluence of 1.35(-0.07,+0.07)x10^-4 erg/cm2,
and a 64-ms peak flux, measured from T0+8.544 s,
of 2.23(-0.28,+0.29)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the burst
(measured from T0 to T0+20.736 s)
is best fit in the 20 keV - 10 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.82(-0.03,+0.03),
the high energy photon index beta = -3.00(-0.50,+0.27),
the peak energy Ep = 472(-24,+23) keV
(chi2 = 139/97 dof).
The spectrum near the maximum count rate
(measured from T0+8.192 to T0+8.704 s)
is best fit in the 20 keV - 10 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with alpha = -0.72(-0.09,+0.09)
and Ep = 605(-68,+80) keV (chi2 = 51/63 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.5
(chi2 = 50/62 dof).
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.
GCN Circular 29090
Subject
IPN triangulation of GRB 201218A
Date
2020-12-19T01:12:10Z (5 years ago)
From
Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>
K. Hurley, on behalf of the IPN,
I. G. Mitrofanov, D. V. Golovin, A. S. Kozyrev, M. L. Litvak,
and A. B. Sanin, on behalf of the HEND-Odyssey GRB team,
D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, A. Ridnaia,
and T. Cline on behalf of the Konus-Wind team,
S. Barthelmy, J. Cummings, H. Krimm, and D. Palmer,
on behalf of the Swift-BAT team,
and
W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr,
on behalf of the GRS-Odyssey GRB team, report:
The long-duration, very bright GRB 201218A
(Fermi-GBM detection: The Fermi GBM team, GCN Circ. 29081;
BALROG localization: Biltzinger et al., GCN Circ. 29083)
has been detected by Fermi (GBM trigger 629957660),
Konus-Wind, Mars-Odyssey (HEND), and Swift (BAT),
so far, at about 15256 s UT (04:14:16).
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:
288.498 (19h 13m 59s) +28.356 (+28d 21' 23")
Corners:
288.470 (19h 13m 53s) +28.144 (+28d 08' 38")
288.400 (19h 13m 36s) +28.556 (+28d 33' 23")
288.526 (19h 14m 06s) +28.569 (+28d 34' 08")
288.596 (19h 14m 23s) +28.156 (+28d 09' 22")
---------------------------------------------
The error box area is 168 sq. arcmin, and its maximum
dimension is 26 arcmin (the minimum one is 6.7 arcmin).
The Sun distance was 56 deg.
The IPN localization is consistent with, but reduces the area of, the
Fermi RoboBA and BALROG localizations (GCN Circ. 29081 and 29083).
A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB201218_T15255/IPN/
The Konus-Wind time history and spectrum will be given in a forthcoming
GCN Circular.
GCN Circular 29087
Subject
Fermi GRB 201218A: Global MASTER-Net observations report
Date
2020-12-18T19:15:25Z (5 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin,
V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva,
D.Kuvshinov, D. Cheryasov
(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, O.Ershova
(Irkutsk State University, API),
A. Tlatov, D. Dormidontov
(Kislovodsk Solar Station of the Pulkovo Observatory),
V. Yurkov, A. Gabovich, Yu. Sergienko
(Blagoveschensk Educational State University)
MASTER-IAC robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Spain (IAC Teide Observatory) started inspect of the Fermi GRB 201218A ( Fermi GBM team, GCN 29081) errorbox 53279 sec after notice time and 53345 sec after trigger time at 2020-12-18 19:03:21 UT, with upper limit up to 16.5 mag. Observations started at twilight. The observations began at zenith distance = 64 deg. The sun altitude is -11.5 deg.
The galactic latitude b = 7 deg., longitude l = 57 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=1505659
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
22028 | 2020-12-18 10:20:53 | MASTER- | (19h 12m 49.70s , +21d 30m 56.1s) | C | 60 | 15.4 |
23215 | 2020-12-18 10:40:41 | MASTER- | (19h 12m 56.18s , +21d 28m 59.3s) | C | 60 | 13.0 |
53435 | 2020-12-18 19:03:21 | MASTER-IAC | (19h 01m 57.16s , +23d 55m 31.2s) | C | 180 | 16.5 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
GCN Circular 29083
Subject
GRB 201218A: BALROG localization (Fermi Trigger 629957660 / GRB 201218177)
Date
2020-12-18T04:43:49Z (5 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
629957660 at 04:14:15 on 18 Dec. 2020 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) = 287.38+/-0.29 deg
Decl.(2000.0) = 26.80+/-0.30 deg
We estimate an additional systematic error of 1 deg.
Further details are available at:
https://grb.mpe.mpg.de/grb/GRB201218177/
The Healpix map can be downloaded from:
https://grb.mpe.mpg.de/grb/GRB201218177/healpix
The location parameters are available as JSON at:
https://grb.mpe.mpg.de/grb/GRB201218177/json
GCN Circular 29081
Subject
GRB 201218A: Fermi GBM Final Real-time Localization
Date
2020-12-18T04:24:37Z (5 years ago)
From
Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>
The Fermi GBM team reports the detection of a likely LONG GRB
At 04:14:15 UT on 18 Dec 2020, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 201218A (trigger 629957660.899176 / 201218177).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 286.9, Dec = 24.2 (J2000 degrees, equivalent to J2000 19h 07m, 24d 11'), with a statistical uncertainty of 1.0 degrees.
The angle from the Fermi LAT boresight is 95.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn201218177/quicklook/glg_skymap_all_bn201218177.png
The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn201218177/quicklook/glg_healpix_all_bn201218177.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn201218177/quicklook/glg_lc_medres34_bn201218177.gif