GRB 201227A
GCN Circular 29281
Subject
GRB 201227A: continued Chilescope confirmation of variability of possible optical counterpart, redshift estimating
Date
2021-01-08T16:20:33Z (5 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
S. Belkin (IKI), A. Pozanenko (IKI), P. Minaev (IKI), M. Krugov (FAI)
report on behalf of GRB IKI FuN collaboration:
We continued observations of the field of XRT #2 sources (D'Elia et al.,
GCN 29202) (hereafter X2) found in IPN localization area (Svinkin et
al., GCN 29182) of GRB 201227A (Ursi et al., GCN 29179; Xiao et al., GCN
29187; Svinkin et al., GCN 29196; Lesage et al., GCN 29206; Marisaldi et
al., GCN 29276) with Chilescope RC-1000 on 2021-01-01 and 2021-01-08 in
r'-filter.
The X2_O2 object found in previous observation on 2020-12-29 at r'(AB)=
20.5 (Belkin et al., GCN 29208; see also Izzo et al., GCN 29207) is not
detected on 2021-01-01 with an upper limit of r'(AB) > 20.6 and barely
detected on 2021-01-08 at r'(AB)=22.6. Now we confirm the variability of
the object of X2_O2 and suggest the optical object X2_02 could be a
counterpart of GRB 201227A. In the last image on 2021-01-08, the object
X2_O2 could be the host galaxy. A finding chart of the X2_O2 can be found in
http://grb.rssi.ru/GRB201227A/GRB201227A_r_FC_201229_2100108.png
Preliminary photometry of the X2_O2 is following
Date UT start t-T0 Filter Exp. OT(AB) Err. UL(AB) FWHM
(mid, days) (s)
2021-01-01 05:57:21 4.63072 r' 5*600 n/d n/d 20.6 1.5"
2021-01-08 04:15:45 11.5636 r' 3*1200 22.6 0.4 22.5 1.4"
The photometry is based on nearby stars from the APASS_DR8
RA DEC r
11:19:31.40904 -73:35:47.6880 14.090
11:19:44.89128 -73:34:49.6092 15.180
11:19:36.65304 -73:36:30.2112 15.307
In addition we investigated a position of the GRB 201227A on the EHD
diagram (see Minaev et al., MNRAS, 492, 1919, 2020). The position of
GRB 201227A based on Konus-Wind data (Svinkin et al., GCN Circ. 29196)
can be found in
http://grb.rssi.ru/GRB201227A/GRB201227A_EH_T90i.png
We can exclude the GRB 201227A as a giant flare event of SGR since there
is no nearby galaxies in the IPN error box. We can identify the GRB
201227A as short GRB at a redshift of z > 0.05.
GCN Circular 29276
Subject
GRB 201227A: ASIM observation
Date
2021-01-07T14:29:38Z (5 years ago)
From
Martino Marisaldi at U of Bergen, Norway <martino.marisaldi@uib.no>
M. Marisaldi (University of Bergen), A. Mezentsev (University of Bergen),
N. ��stgaard (University of Bergen), V. Reglero (University of Valencia)
and T. Neubert (DTU Space) report on behalf of the ASIM Team:
At 15:14:07.380 UT on 27 December 2020, the Atmosphere-Space Interactions Monitor (ASIM)
mission triggered on the very short and bright GRB 201227A
(AGILE detection: Ursi et al., GCN Circ. 29179; IPN triangulation: Svinkin et al., GCN Circ. 29182;
Swift observations: Evans, GCN Circ. 29184; Evans, GCN Circ. 29185; D���Elia et al., GCN Circ. 29202;
Insight-HXMT/HE detection: Xiao et al., GCN Circ. 29187; Konus-Wind observation: Svinkin et al., GCN Circ. 29196;
Fermi GBM observation: Lesage et al., GCN Circ. 29206; GRAWITA VST observation: Izzo et al., GCN Circ. 29207
Chilescope observation: Belkin et al., GCN Circ. 29208)
Photon by photon data with <1 microsecond time resolution have been
collected for a time interval of two seconds centered at the trigger time.
As seen by the Modular X- and Gamma-Ray Sensor (MXGS) onboard ASIM
the burst consists of a single emission episode about 60 ms in duration, with evidence of time variability.
The emission is detected in the MXGS High Energy Detector (HED),
sensitive in the range 0.3 to >30 MeV.
Significant emission is observed up to about 3 MeV.
The MXGS Low Energy Detector (LED), sensitive in the range 0.05 to 0.4 MeV,
was not active at trigger time.
ASIM is an ESA mission onboard the International Space Station dedicated to the
observation of Terrestrial Gamma-ray Flashes (TGFs) and Transient Luminous Events (TLEs)
operative since June 2018 (Neubert et al., Space Sci Rev (2019) 215:26
https://doi.org/10.1007/s11214-019-0592-z <https://doi.org/10.1007/s11214-019-0592-z> ).
The payload includes the Modular X- and Gamma-Ray Sensor (MXGS)
(��stgaard et al., Space Sci Rev (2019) 215:23 https://doi.org/10.1007/s11214-018-0573-7 <https://doi.org/10.1007/s11214-018-0573-7> ),
and the the Modular Multispectral Imaging Array (MMIA)
(Chanrion et al., Space Sci Rev (2019) 215:28 https://doi.org/10.1007/s11214-019-0593-y <https://doi.org/10.1007/s11214-019-0593-y> ).
The ASIM Science Data Centre (ASDC) website is https://asdc.space.dtu.dk/ <https://asdc.space.dtu.dk/>
GCN Circular 29208
Subject
GRB 201227A: Chilescope optical observations, possible optical counterpart
Date
2020-12-30T21:14:02Z (5 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
S. Belkin (IKI), A. Pozanenko (IKI), M. Krugov (FAI), P. Minaev (IKI)
report on behalf of GRB IKI FuN collaboration:
We observed the field of XRT 1-3 sources (D'Elia et al., GCN 29202)
(hereafter X1,X2,X3) found in IPN localization area (Svinkin et al.,
GCN 29182) of GRB 201227A (Ursi et al., GCN 29179; Xiao et al., GCN
29187; Svinkin et al., GCN 29196; Lesage et al., GCN 29206) with
Chilescope RC-1000 starting on 2020-12-29 (UT) 04:02:05 in r'-filter.
The X3 source was observed by one 300 s exposure, and the filed of X1,X2
was observed by 3*300 s exposure. The limiting magnitude of single
exposure of X3 and the stacked 3*300 s exposure is about r'=20.9.
There are two optical sources close or on the edge of the XRT error
circle localization of X3. Both sources are present in USNO-B1.0 and our
photometry of the sources show no excess in brightness in comparison
with any R-mag of USNO-B1.0.
Also there are two optical sources close or on the edge of the XRT error
circle localization of X1. Both source are also present in USNO-B1.0 and
our photometry of the sources show no excess in brightness in comparison
with any R-mag of USNO-B1.0.
At the edges of X2 error circle we found two sources which not presented
in USNO-B1.0. The coordinates of the first one (X2_O1) is RA(J2000)=11h
22m 29.34s, Dec(J2000)=-73d 28��� 44.9������. The photometry of the source is
r'= 20.50 +/-0.29 and the source is barely visible in DSS2 plate. The
coordinates of second one (X2_02) is RA(J2000)=11h 22m 27.94s,
Dec(J2000)=-73d 28��� 50.6������. The photometry of the source is r'= 20.52
+/-0.29 and the source is not presented in DSS2 plate. We may suggest
the optical object X2_02 could be a counterpart of GRB 201227A.
The photometry is based on nearby stars from the APASS_DR8 and still
preliminary
RA DEC r
11:19:31.40904 -73:35:47.6880 14.090
11:19:44.89128 -73:34:49.6092 15.180
11:19:36.65304 -73:36:30.2112 15.307
Taking into account that early more deep observations of the IPN field
by GRAWITA VST-ESO PARANAL (Izzo et al., GCN 29207) does no show any
counterpart we may suggest the X2_O2 source (RA(J2000)=11h 22m 27.936s,
Dec(J2000)=-73d 28��� 50.55������) is a possible optical counterpart or
kilonova of GRB 201227A.
GCN Circular 29207
Subject
GRB 201227A: GRAWITA VST-ESO PARANAL observations
Date
2020-12-30T18:38:24Z (5 years ago)
From
Paolo D'Avanzo at INAF-OAB <pda.davanzo@gmail.com>
L. Izzo (DARK/NBI), P. D'Avanzo (INAF-OAB), E. Brocato (INAF-OAA/INAF-OAR) report on behalf of GRAWITA:
We observed the field of the short GRB 201227A (Fermi/GBM trigger 630774852; Ursi et al., GCN Circ. 29179;
Svinkin et al., GCN Circ. 29182; Xiao et al., GCN Circ. 29187; Svinkin et al., GCN Circ. 29196; Lesage et al.,
GCN Circ. 29206) with the VLT Survey Telescope (VST) equipped with OmegaCAM (1 square degree FOV;
Proposal ID ESO 0106.D-0343(A)).
We obtained one epoch of observations with the r filter on 2020-12-28 between 07:10:07 UT and 07:32:12 UT
(i.e. between 15.93 and 16.30 hours after the burst t0).
The observations cover 2 square degrees enclosing ~ 100% of the IPN localization box (Svinkin et al., GCN Circ. 29182).
Each one square degree pointing is the coaddition of five dithered exposures for a total exposure time of 300 seconds per
pointing.
From a preliminary analysis, we find no clear optical counterpart of GRB 201227A inside the IPN error box down to a 3sigma
limiting magnitude of r ~ 22 (AB, calibrated against the SkyMapper survey).
In particular, we do not find optical countepart candidates at the position of the four Swift/XRT sources reported by D'Elia et al.
(GCN Circ. 29202) nor at the position of the only galaxy listed in the GLADE catalogue found inside the IPN error box (galaxy
coordinates (J2000): RA, Dec = 168.85910, -73.94917, redshift z = 0.1379; Dalya et al., 2018, MNRAS, 479, 2347).
Further analysis is in progress.
We acknowledge excellent support from the ESO observing staff at Paranal, in particular Bin Yang.
GCN Circular 29206
Subject
GRB 201227A: Fermi GBM observation
Date
2020-12-30T14:00:33Z (5 years ago)
From
Rachel Dunwoody at UCD <rachel.dunwoody@ucdconnect.ie>
S. Lesage, P. Veres, C. Meegan (all UAH), J. Mangan (UCD) and R. Dunwoody
(UCD)
report on behalf of the Fermi GBM Team:
"At 15:14:07.41 UT on 23 December 2020, the Fermi Gamma-Ray Burst Monitor
(GBM)
triggered and located GRB 201227A (trigger 630774852 / 201227635),
which was also detected by Konus-Wind (Svinkin et al. GCN 29196),
Insight-HXMT (Xiao et al., GCN 29187),
AGILE (Ursi et al., GCN 29179) and IPN (Svinkin et al., GCN 29182).
The GBM on-ground location is consistent with the IPN position.
The angle from the Fermi LAT boresight at the GBM trigger time is 135
degrees.
The GBM light curve consists of a short bright pulse
with a duration (T90) of about 0.1 s (50-300 keV).
The time-averaged spectrum from T0-64 ms to T0+128 ms is
best fit by a power law function with an exponential
high-energy cutoff. The power law index is -0.47 +/- 0.07 and
the cutoff energy, parameterized as Epeak, is 1076 +/- 96 keV.
The event fluence (10-1000 keV) in this time interval is
(3.6 +/- 0.1)E-6 erg/cm^2. The 64-ms peak photon flux measured
starting from T0 in the 10-1000 keV band
is 100 +/- 5 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 29202
Subject
GRB 201227A: Swift-XRT observations
Date
2020-12-30T00:59:11Z (5 years ago)
From
Aaron Tohuvavohu at U Toronto <aaron.tohu@gmail.com>
V. D'Elia (SSDC & INAF-OAR), A. D'Ai (INAF-IASFPA), A. Tohuvavohu (U.
Toronto), B. Sbarufatti (PSU), D.N. Burrows (PSU), K.L. Page (U.
Leicester), A.P. Beardmore (U. Leicester), A. Melandri (INAF-OAB) and
P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team:
Swift-XRT has performed follow-up observations of the IPN-detected
burst GRB 201227A (Ursi et al. GCN Circ. 29179) in a series of
observations tiled on the sky. The total exposure time is 7.5 ks,
distributed over 4 tiles; the maximum exposure at a single sky location
was 5.3 ks. The data were collected between T0+51.6 ks and T0+80.7 ks,
and are entirely in Photon Counting (PC) mode.
Four uncatalogued X-ray sources have been detected, however none of
them is above the RASS limit or shows definitive signs of fading.
Therefore, at the present time we cannot identify which, if any, is the
afterglow. Details of these sources are given below:
Source 1:
RA (J2000.0): 170.6083 = 11:22:25.99
Dec (J2000.0): -73.4880 = -73:29:16.9
Error: 7.4 arcsec (radius, 90% conf.)
Count-rate: (4.4 [+1.7, -1.4])e-3 ct s^-1
Distance: 670 arcsec from IPN position.
Flux: (9.0 [+3.5, -2.8])e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV)
Source 2:
RA (J2000.0): 170.6190 = 11:22:28.57
Dec (J2000.0): -73.4798 = -73:28:47.2
Error: 4.8 arcsec (radius, 90% conf.)
Count-rate: (3.6 [+1.6, -1.3])e-3 ct s^-1
Distance: 698 arcsec from IPN position.
Flux: (1.34 [+0.60, -0.47])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)
Source 3:
RA (J2000.0): 169.8508 = 11:19:24.19
Dec (J2000.0): -73.5866 = -73:35:11.9
Error: 5.6 arcsec (radius, 90% conf.)
Count-rate: (2.8 [+1.4, -1.1])e-3 ct s^-1
Distance: 290 arcsec from IPN position.
Source 4:
RA (J2000.0): 171.2953 = 11:25:10.87
Dec (J2000.0): -73.6326 = -73:37:57.4
Error: 4.4 arcsec (radius, 90% conf.)
Count-rate: (4.2 [+2.6, -1.9])e-3 ct s^-1
Distance: 1194 arcsec from IPN position.
The results of the XRT-team automatic analysis of the tiled XRT
observations, including a position-specific upper limit calculator, are
available at https://www.swift.ac.uk/xrt_products/TILED_GRB00096.
This circular is an official product of the Swift-XRT team.
GCN Circular 29196
Subject
Konus-Wind observation of GRB 201227A
Date
2020-12-29T16:42:04Z (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 short-duration, very bright GRB 201227A
(AGILE detection: Ursi et al., GCN Circ. 29179;
IPN triangulation: Svinkin et al., GCN Circ. 29182;
Insight-HXMT/HE detection: Xiao et al., GCN Circ. 29187)
triggered Konus-Wind at T0=54846.705 s UT (15:14:06.705).
The burst light curve shows a multipeaked structure
which starts at ~T0-28 ms and has a total duration of ~106 ms.
The emission is seen up to ~4 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB201227_T54846/
As observed by Konus-Wind, the burst
had a fluence of 4.30(-0.52,+0.54)x10^-6 erg/cm2,
and a 16-ms peak flux, measured from T0,
of 1.05(-0.18,+0.18)x10^-4 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the burst
(measured from T0 to T0+0.064 s)
is best fit in the 20 keV - 4 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with alpha = -0.17(-0.18,+0.21)
and Ep = 870(-130,+151) keV (chi2 = 17/19 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.3
(chi2 = 17/18 dof).
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.
GCN Circular 29187
Subject
GRB 201227A: Insight-HXMT/HE detection
Date
2020-12-28T15:00:13Z (5 years ago)
From
Shuo Xiao at IHEP <xiaoshuo@ihep.ac.cn>
S. Xiao, C. Cai, Y. F. Du, Y. G. Zheng, Q. Luo, Q. B. Yi,
Y. Huang, C. K. Li, G. Li, X. B. Li, J. Y. Liao, S. L. Xiong,
C. Z. Liu, X. F. Li, Z. W. Li, Z. Chang, A. M. Zhang,
Y. F. Zhang, X. F. Lu, C. L. Zou (IHEP), Y. J. Jin,
Z. Zhang (THU), T. P. Li (IHEP/THU), F. J. Lu, L. M. Song,
M. Wu, Y. P. Xu, S. N. Zhang (IHEP),
report on behalf of the Insight-HXMT team:
At 2020-12-27T15:14:07.400 (T0), Insight-HXMT/HE detected
GRB 201227A (trigger ID: HEB201227634) in a routine search of the data,
which also triggered Fermi/GBM (trigger 630774852) and
AGILE Mini-CALorimeter (GCN#29179