GRB 171120A
GCN Circular 22209
Subject
GRB 171120A CALET Gamma-Ray Burst Monitor detection
Date
2017-12-08T00:27:12Z (8 years ago)
From
Takanori Sakamoto at AGU <tsakamoto@phys.aoyama.ac.jp>
Y. Yamada, A. Yoshida, T. Sakamoto, Y. Kawakubo, M. Moriyama,
A. Tezuka, S. Matsukawa (AGU), K. Yamaoka (Nagoya U), S. Nakahira (RIKEN),
I. Takahashi (IPMU), Y. Asaoka, S. Ozawa, S. Torii (Waseda U), Y. Shimizu,
T. Tamura (Kanagawa U), W. Ishizaki (ICRR), M. L. Cherry (LSU),
S. Ricciarini (U of Florence), A. V. Penacchioni, P. S. Marrocchesi (U of Siena)
and the CALET collaboration:
The long-duration GRB 171120A (Tohuvavohu et al., GCN circ. 22133; Longo et al.,
GCN circ. 22136; Frederiks et al., GCN circ. 22142; Sharma et al., GCN circ. 22143;
Li et al., GCN circ. 22149) triggered the CALET Gamma-ray Burst Monitor (CGBM)
at 13:20:02 on 20 November 2017. The burst signal was seen by the all CGBM
instruments.
The light curve of the SGM shows two largely separated episodes. The first
episode starts at T0, peaks at T+1 sec and ends at T+4 sec. The second
episode starts T+38 sec, peaks at T+40 sec and ends at T+46 sec.
The T90 duration measured by the SGM data is 44.4 +- 0.9 sec (40-1000 keV).
The light curve is available at
http://cgbm.calet.jp/cgbm_trigger/flight/1195219087/
The CALET data used in this analysis are provided by the Waseda CALET Operation
Center located at the Waseda University.
GCN Circular 22149
Subject
GRB 171120A: Insight-HXMT detection
Date
2017-11-23T15:03:23Z (8 years ago)
From
Zhengwei Li at IHEP <lizw@ihep.ac.cn>
Z. W. Li, J. Y. Liao, C. K. Li, X. B. Li, S. L. Xiong, C. Z. Liu,
X. F. Li, Z. Chang, X. F. Lu, J. L. Zhao, A. M. Zhang, Y. F. Zhang,
C. L. Zou (IHEP), Y. J. Jin, Z. Zhang (THU), T. P. Li (IHEP/THU),
F. J. Lu, L. M. Song, H. Y. Wang, M. Wu, Y. P. Xu, S. N. Zhang (IHEP),
report on behalf of the Insight-HXMT team:
During the commissioning phase, at 2017-11-20T13:20:02.00 (T0),
Insight-HXMT detected GRB 171120A (trigger ID: HEB171120555)
in a routine search of the data, which was also observed by
Swift/BAT (A. Tohuvavohu et al, GCN Circ.22133), Swift/XRT(P.A. Evans
et al, GCN Circ.22135),Fermi/GBM(M.Stanbro et al, GCN Circ.22138),
Fermi/LAT(F. Longo et al, GCN Circ.22136), Konus-Windan(D.Frederiks
et al, GCN Circ.22142) and AstroSat/CZTI (V.Sharma et al, GCN Circ.22143).
The Insight-HXMT light curve consists of two pulses with a duration (T90)
of 39.9s measured from T0+0.5s. The 200-ms peak rate, measured from
T0+0.6s, is 6895.7 cnts/sec. The total counts from this burst is 5746.9
counts.
URL_LC: http://www.hxmt.org/images/GRB/HEB171120555_lc.jpg
All measurements above are made with the CsI detectors operating in the
regular mode with the energy range of about 80-800 keV (record energy).
Only gamma-rays with energy greater than about 200 keV can penetrate
the spacecraft and leave signals in the CsI detectors installed inside
of the telescope.
The time-averaged spectrum from T0-0.2 to T0+1.0 s is adequately fit by
a Power Law model with spectral index = -1.96 +/- 0.07 . The energy fluence
is (6.20 +/- 0.33) E-06 erg/cm^2 in 200 - 5000 keV in this time interval.
The analysis results presented above are preliminary; final results will
be published elsewhere.
Insight-HXMT is the first Chinese space X-ray telescope, which was funded
jointly by the China National Space Administration (CNSA) and the Chinese
Academy of Sciences (CAS). More information about it could be found at:
http://www.hxmt.org/index.php/enhome .
GCN Circular 22145
Subject
GRB 171120A: Xinglong-2.16m optical upper limit
Date
2017-11-22T04:24:59Z (8 years ago)
From
Dong Xu at NAOC/CAS <dxu@nao.cas.cn>
Z.P. Zhu, H.X. Feng, D. Xu (NAOC), Y. Zhao, F. Xiao (NAOC), S.B. Qian
(YNAO), Y.D. Hu (IAA-CSIC) report
We observed the field of GRB 171120A (Tohuvavohu et al., GCN 22133)
using the 2.16-m telescope located at Xinglong, Hebei, China, equipped
with BFOSC. We obtained 1x600s and 2x900s R-band frames, starting at
18:54:02 UT on 2017-11-20, i.e., 5.57 hr after the BAT trigger.
No optical source was detected in the stacked image at the XRT position
(Evens et al., GCN 22135), down to the limiting magnitude of R~21.5 mag
at the median time of 5.95 hr post-burst, calibrated with the SDSS field.
GCN Circular 22144
Subject
GRB 171120A: Swift/UVOT Upper Limits
Date
2017-11-21T21:21:20Z (8 years ago)
From
Jeffrey Gropp at PSU <jdg44@psu.edu>
J. D. Gropp (PSU) and A. Tohuvavohu (PSU)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 171120A
99 s after the BAT trigger (Tohuvavohu et al., GCN Circ. 22133).
No optical afterglow consistent with the refined XRT position
(Evans et al. GCN Circ. 22135)
is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white_FC 99 249 147 >19.9
u_FC 311 561 246 >19.7
white 99 5989 560 >21.1
v 640 6399 413 >19.1
b 566 5784 413 >20.9
u 311 11713 811 >20.7
w1 5174 11532 1082 >21.0
m2 9724 10624 886 >21.0
w2 4559 6194 393 >21.0
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.02 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 22143
Subject
GRB 171120A: AstroSat CZTI detection
Date
2017-11-21T21:06:13Z (8 years ago)
From
Vidushi Sharma at IUCAA <vidushi@iucaa.in>
V. Sharma and D. Bhattacharya (IUCAA), V. Bhalerao (IIT-B), A. R. Rao (TIFR) and S. Vadawale (PRL) report on behalf of the Astrosat CZTI collaboration:
Analysis of Astrosat CZTI data showed the detection of GRB 171120A, which was also detected by Swift-BAT (Tohuvavohu et al., GCN 22133), Fermi-GBM (trigger 532876807/171120556) and Fermi-LAT (Longo F. et al., GCN 22136).
The source was clearly detected in the 40-200 keV energy range. The light curve of the CZT detector shows a single peak of emission at 13:20:02 UT. The measured peak count rate is 367.4 cts/s above the background in combined data of four quadrants, with a total of 634 cts. The local mean background count rate was 307.6 cts/s. Using cumulative rates, we measure a T90 of 6.8 s.
It was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The Veto light curve shows a strong peak coincident with the peak in the CZT detector and a weaker second peak ~39 s later.
CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project.
GCN Circular 22142
Subject
Konus-Wind observation of GRB 171120A
Date
2017-11-21T12:48:30Z (8 years ago)
From
Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru>
D. Frederiks, S. Golenetskii, R.Aptekar, P. Oleynik, M. Ulanov,
D. Svinkin, A. Tsvetkova, A.Lysenko, A. Kozlova, and T. Cline,
on behalf of the Konus-Wind team, report:
The long GRB 171120A (Swift/BAT detection: Tohuvavohu et al., GCN 22133;
Stamatikos et al., GCN 22139; Fermi-LAT detection: Longo et al.,
GCN 22136; Fermi-GBM detection: Stanbro et al., GCN 22138)
triggered Konus-Wind at T0=48000.683 s UT (13:20:00.683).
The KW light curve shows two separate emission episodes.
A total duration of the burst is ~44 s.
The emission is seen up to ~10 MeV.
As observed by Konus-Wind, the burst had a fluence of
1.7(-0.3,+0.5)x10^-5 erg/cm2 and a 64-ms peak energy flux,
measured from T0+1.644, of (1.29 �� 0.13)x10^-5 erg/cm2
(both in the 20 keV - 10 MeV energy range).
The time-integrated spectrum (measured from T0 to T0+49.408 s)
is best fit in the 20 keV - 15 MeV range by a cutoff power-law
(CPL) function with the following model parameters:
the photon index alpha = -1.59(-0.19,+0.23),
and the peak energy Ep = 200(-56,+183) keV,
chi2 = 84/98 dof.
Fitting this spectrum with the GRB (Band) function yields
the same alpha and Ep, and an upper limit on beta of -2.0.
The spectrum near the peak count rate (measured from T0+0.128
to T0+0.256 s) is best fit in the 20 keV - 15 MeV range by
the CPL function with the following model parameters:
the photon index alpha = -0.33(-0.30,+0.35),
and the peak energy Ep = 305(-41,+53) keV,
chi2 = 39/36 dof.
Fitting this spectrum with the GRB (Band) function yields
similar alpha and Ep, and an upper limit on beta of -2.7.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB171120_T48000/
All the quoted errors are estimated at the 90% confidence level.
All the presented results are preliminary.
GCN Circular 22141
Subject
GRB171120A: GWAC-F60A upper limit
Date
2017-11-21T11:39:32Z (8 years ago)
From
L.P. Xin at NAOC <xlp@nao.cas.cn>
L. P. Xin, W. L. Dong, P. P. Zhang, X. H. Han, J. Y. Wei, E. W. Liang,
X. G. Wang, Y. J. Xiao, Y. G. Yang, X. M. Lu, L. Huang, H. B. Cai,
X. M. Meng, Y. L. Qiu, Y. Xu, Y. J. Xiao, Y. T. Zheng, R. S. Zhang, J. Wang,
C. Wu, J. S. Deng, D. W. Xu, T. Damien and H. L. Li report:
We observed GRB 171120A (Tohuvavohu et al., GCN 22133) with
GWAC-F60A 60cm optical telescope at 19:06:58 UT, Nov. 20th 2017,
about 5.75 hours after the burst.
No any new source was not detected in the XRT error circle
(Evens et al., GCN 22135) in our 15*300 sec stacked R-band image
down to the 3 sigma limit of about 19.5 mag at the mid time of 6.25 hours
after the burst. The brightness was calibrated by USNO B1.0 R2 catalogues.
GWAC-F60A is operated by Guangxi university and NAOC, CAS,
at Xinglong observatory, China.
The message may be cited.
GCN Circular 22140
Subject
GRB 171120A: MITSuME Akeno optical upper limits
Date
2017-11-21T10:18:12Z (8 years ago)
From
Katsuhiro L. Murata at Nagoya U <murata@u.phys.nagoya-u.ac.jp>
H. Mamiya, R. Itoh, K. L. Murata, T. Yoshii, Y. Tachibana, S. Harita, K.
Morita, T. Ozawa, K. Shiraishi, Y. Yatsu, and N. Kawai (Tokyo Tech)
report on behalf of the MITSuME collaboration:
We searched for the optical counterpart of GRB 171120A (A. Tohuvavohu et
al., GCN Circular #22133) with the optical three color (g', Rc, and Ic) CCD
cameras attached to the MITSuME 50 cm telescope of Akeno Observatory,
Yamanashi, Japan.
The observation started on 2017-11-20 15:38:32.17 UT. We did not find any
new point source within enhanced XRT circle (P.A. Evans al., GCN Circular
#22135) in all three bands.
We obtained following limits for the magnitudes.
T0+[hour] MID-UT T-EXP[sec] g' Rc Ic
------------------------------------------------------------------------------------------------------
~3.26 18:40:07.63 9960 >21.5 >20.7 >19.8
------------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
We used GSC2.3 catalog for flux calibration.
GCN Circular 22139
Subject
GRB 171120A: Swift-BAT refined analysis
Date
2017-11-21T04:19:31Z (8 years ago)
From
Amy Lien at GSFC <amy.y.lien@nasa.gov>
M. Stamatikos (OSU), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), H. A. Krimm (NSF/USRA),
A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), T. Sakamoto (AGU),
A. Tohuvavohu (PSU), T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):
Using the data set from T-240 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 171120A (trigger #791201)
(Tohuvavohu et al., GCN Circ. 22133). The BAT ground-calculated position is
RA, Dec = 163.774, 22.461 deg which is
RA(J2000) = 10h 55m 05.8s
Dec(J2000) = +22d 27' 38.2"
with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 14%.
The mask-weighted light curve shows a multi-peaked structure that starts
at ~T-15 s and ends at ~T+65 s. The two main peaks occur at ~T0 and ~T+40 s,
respectively. T90 (15-350 keV) is 64 +- 16 sec (estimated error including
systematics).
The time-averaged spectrum from T-15.53 to T+64.47 sec is best fit by a power law
with an exponential cutoff. This fit gives a photon index 1.06 +- 0.28,
and Epeak of 86.0 +- 19.0 keV (chi squared 55.57 for 56 d.o.f.). For this
model the total fluence in the 15-150 keV band is 8.6 +- 0.3 x 10^-6 erg/cm2
and the 1-sec peak flux measured from T+39.97 sec in the 15-150 keV band is
11.4 +- 0.5 ph/cm2/sec. A fit to a simple power law gives a photon index
of 1.67 +- 0.06 (chi squared 70.86 for 57 d.o.f.). All the quoted errors
are at the 90% confidence level.
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/791201/BA/
GCN Circular 22138
Subject
GRB 171120A: Fermi GBM Detection
Date
2017-11-21T00:44:27Z (8 years ago)
From
Matthew Stanbro at UAH/Fermi <mcs0001@uah.edu>
M. Stanbro, C. Meegan, (UAH) and A von Kienlin (MPE)
report on behalf of the Fermi GBM Team:
"At 13:20:02.37 UT on 20 November 2017, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 171120A (trigger 532876807 / 171120556)
which was also detected by the Swift/BAT (A. Tohuvavohu et al. 2017, GCN
22133)
and Fermi LAT (F. Longo et al. 2017, GCN 22136).
The GBM on-ground location is consistent with the Swift position.
The trigger resulted in an Autonomous Repoint Request (ARR)
by the GBM Flight Software owing to the high peak flux
of the GRB. This ARR was accepted and the spacecraft slewed to the GBM
in-flight
location.
The GBM light curve consists of 2 pulses
with a duration (T90) of about 44 s (50-300 keV).
The time-averaged spectrum from T0+0.002 s to T0+44.897 s is
best fit by a Band function with Epeak = 141 +/- 12 keV,
alpha = -0.91 +/- 0.06, and beta = -2.16 +/- 0.09.
The event fluence (10-1000 keV) in this time interval is
(1.80 +/- 0.05)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+0.10 s in the 10-1000 keV band
is 35.69 +/- 0.51 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."
GCN Circular 22137
Subject
GRB 171120A: Swift-XRT refined Analysis
Date
2017-11-20T21:49:56Z (8 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
K.L. Page (U. Leicester), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), A.
Melandri (INAF-OAB), A. Tohuvavohu (PSU), S. J. LaPorte (PSU), J.A.
Kennea (PSU), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester)
and report on behalf of the Swift-XRT team: report on behalf of the
Swift-XRT team:
We have analysed 8.2 ks of XRT data for GRB 171120A, from 78 s to 22.5
ks after the BAT trigger. The data comprise 337 s in Windowed Timing
(WT) mode (the first 9 s were taken while Swift was slewing) with the
remainder in Photon Counting (PC) mode.
The late-time light curve (from T0+3.9 ks) can be modelled with a
power-law decay with a decay index of alpha=0.41 (+/-0.09).
A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.78 (+0.15, -0.14). The
best-fitting absorption column is 2.34 (+0.28, -0.26) x 10^22 cm^-2,
in excess of the Galactic value of 1.2 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.92 (+/-0.18) and a
best-fitting absorption column of 2.4 (+/-0.3) x 10^22 cm^-2. The
counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum is 6.6 x 10^-11 (1.4 x 10^-10) erg cm^-2
count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 2.4 (+/-0.3) x 10^22 cm^-2
Galactic foreground: 1.2 x 10^20 cm^-2
Excess significance: 12.8 sigma
Photon index: 1.92 (+/-0.18)
If the light curve continues to decay with a power-law decay index of
0.41, the count rate at T+24 hours will be 0.059 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.9 x
10^-12 (8.3 x 10^-12) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00791201.
This circular is an official product of the Swift-XRT team.
GCN Circular 22136
Subject
GRB 171120A: Fermi-LAT detection
Date
2017-11-20T20:39:29Z (8 years ago)
From
Giacomo Vianello at SLAC <giacomov@slac.stanford.edu>
F. Longo (University and INFN, Trieste), G. Vianello (Stanford),
D. Kocevski (NASA/GSFC) and M.Arimoto (Waseda University)
report on behalf of the Fermi-LAT collaboration:
At 13:20:02 on November 20, 2017, Fermi-LAT detected high-energy emission
from GRB 171120A,which was also detected by Swift-BAT (Tohuvavohu et al.,
GCN 22133) and by Fermi-GBM (trigger 532876807/171120556).
The best LAT on-ground location is found to be
RA, Dec = 163.84, 22.40 deg (J2000)
with an error radius of 0.17 deg (90% containment, statistical error only).
This was 24 deg from the LAT boresight at the time of the trigger.
The LAT on-ground position is consistent with the Swift-XRT localization (Evans
et al., GCN 22135).
More than 30 photons above 100 MeV are observed within ~ 6.5 ks seconds of
the trigger. The highest-energy photon is a 3.4 GeV event which is observed
~4.8 ks seconds after the GBM trigger.
The Fermi-LAT point of contact for this burst is:
Francesco Longo (francesco.longo@ts.infn.it).
The Fermi LAT is a pair conversion telescope designed to cover the energy
band from 20 MeV to greater than 300 GeV. It is the product of an international
collaboration between NASA and DOE in the U.S. and many scientific institutions
across France, Italy, Japan and Sweden.
GCN Circular 22135
Subject
GRB 171120A: Enhanced Swift-XRT position
Date
2017-11-20T19:15:06Z (8 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester)
report on behalf of the Swift-XRT team.
Using 2976 s of XRT Photon Counting mode data and 7 UVOT
images for GRB 171120A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 163.79042, +22.45869 which is equivalent
to:
RA (J2000): 10h 55m 9.70s
Dec (J2000): +22d 27' 31.3"
with an uncertainty of 1.6 arcsec (radius, 90% confidence).
This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).
This circular was automatically generated, and is an official product of the
Swift-XRT team.
GCN Circular 22133
Subject
GRB 171120A: Swift detection of a burst
Date
2017-11-20T13:34:57Z (8 years ago)
From
Kim Page at U.of Leicester <klp5@leicester.ac.uk>
A. Tohuvavohu (PSU), A. D'Ai (INAF-IASFPA), A. Deich (PSU),
P. A. Evans (U Leicester), J.D. Gropp (PSU), A. Y. Lien (GSFC/UMBC)
and K. L. Page (U Leicester) report on behalf of the Swift Team:
At 13:20:02 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 171120A (trigger=791201). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 163.787, +22.450 which is
RA(J2000) = 10h 55m 09s
Dec(J2000) = +22d 26' 58"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a multi-peaked
structure with a duration of about 60 sec. The peak count rate
was ~17000 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 13:21:31.0 UT, 88.5 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source with an enhanced position: RA, Dec 163.7911,
22.4584 which is equivalent to:
RA(J2000) = 10h 55m 09.87s
Dec(J2000) = +22d 27' 30.3"
with an uncertainty of 2.5 arcseconds (radius, 90% containment). This
location is 33 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at http://www.swift.ac.uk/sper. We
cannot determine whether the source is fading at the present time.
A power-law fit to a spectrum formed from promptly downlinked event
data does not constrain the column density.
The initial flux in the 2.5 s image was 2.00e-09 erg cm^-2 s^-1 (0.2-10
keV).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 98 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of
the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag.
The 8'x8' region for the list of sources generated on-board covers 100% of the
XRT error circle. The list of sources is typically complete to about 18 mag. No
correction has been made for the expected extinction corresponding to E(B-V) of
0.02.
Burst Advocate for this burst is A. Tohuvavohu (aaronb AT swift.psu.edu).
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)