GRB 190531B
GCN Circular 24738
Subject
GRB 190531B: CALET Gamma-Ray Burst Monitor detection
Date
2019-06-04T08:09:40Z (6 years ago)
From
Valentin Pal'shin at AGU <val@phys.aoyama.ac.jp>
Y. Shimizu (Kanagawa U),
A. Yoshida, T. Sakamoto, V. Pal'shin, S. Sugita (AGU),
Y. Kawakubo (LSU), K. Yamaoka (Nagoya U), S. Nakahira (RIKEN),
Y. Asaoka, S. Ozawa, S. Torii (Waseda U),
T. Tamura (Kanagawa U), N. Cannady (GSFC/UMBC),
M. L. Cherry (LSU), S. Ricciarini (U of Florence),
P. S. Marrocchesi (U of Siena),
and the CALET collaboration:
The long GRB 190531B (Fermi-LAT detection: Axelsson et al.,GCN Circ. 24701;
Fermi-GBM observations: Veres and Meegan, GCN Circ. 24705;
Insight-HXMT/HE detection: Yi et al., GCN Circ. 24713;
Konus-Wind observation: Svinkin et al., GCN Circ. 24730)
triggered the CALET Gamma-ray Burst Monitor (CGBM) at 20:10:20.034 UTC
on 31 May 2019. The burst signal was seen by all CGBM detectors.
No real-time CGBM GCN notice was distributed about this trigger because
the real-time communication from the ISS was off (loss of signal).
The burst light curve shows a multi-peaked emission episode which starts
at T-9.7 sec, peaks at 14.5 sec and ends at T+74.5 sec.
The T90 and T50 durations measured by the SGM data are 36.8 +- 20.0 sec
and 13.5 +- 0.9 sec (40-1000 keV), respectively.
The ground processed light curve is available at
http://cgbm.calet.jp/cgbm_trigger/ground/1243368627/
The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at the Waseda University.
GCN Circular 24731
Subject
GRB 190531B: Swift/UVOT Upper Limits
Date
2019-06-03T19:12:44Z (6 years ago)
From
Kira Simpson at PSU <kira.simpson1984@gmail.com>
GRB 190531B: Swift/UVOT Upper Limits
K. K. Simpson (PSU)
reports on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 190531B
18175 s after the LAT trigger (Axelsson et al., GCN Circ. 24701).
No optical afterglow consistent with the XRT position
(D'Avanzo et al., GCN Circ. 24706)
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 initial exposures
are:
Filter T_start(s) T_stop(s) Exp(s) Mag
b 18661 24137 365 >20.5
u 18497 29702 551 >21.1
w1 18175 29509 1132 >20.7
m2 19630 25766 972 >20.9
w2 18826 24990 1459 >21.3
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.01 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 24730
Subject
Konus-Wind observation of GRB 190531B
Date
2019-06-03T17:52:24Z (6 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. Kozlova, and T. Cline
on behalf of the Konus-Wind team, report:
The long-duration GRB 190531B
(Fermi-GBM detection: The Fermi GBM team, GCN Circ. 24695;
Fermi-GBM observations: Veres and Meegan, GCN Circ. 24705;
Fermi-LAT detection: Axelsson et al., GCN Circ. 24701;
Insight-HXMT/HE detection: Yi et al., GCN Circ. 24713)
triggered Konus-Wind at T0=72616.175 s UT (20:10:16.175).
The burst light curve shows a multipeaked structure
which starts at ~T0-38 s and has a total duration of ~110 s.
The emission is seen up to ~5 MeV.
As observed by Konus-Wind, the burst
had a fluence of 1.51(-0.15,+0.16)x10^-4 erg/cm2,
and a 64-ms peak flux, measured from T0+17.648 s,
of 1.96(-0.30,+0.30)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+83.712 s)
is best fit in the 20 keV - 5 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.73(-0.08,+0.08),
the high energy photon index beta = -2.25(-0.21,+0.14),
the peak energy Ep = 364(-34,+40) keV
(chi2 = 63/72 dof).
The spectrum near the maximum count rate
(measured from T0+15.616 to T0+19.456 s)
is best fit in the 20 keV - 7 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.60(-0.08,+0.09),
the high energy photon index beta = -2.64(-0.46,+0.26),
the peak energy Ep = 520(-53,+55) keV
(chi2 = 87/77 dof).
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB190531_T72616/
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.
GCN Circular 24713
Subject
GRB 190531B: Insight-HXMT/HE detection
Date
2019-06-02T15:16:57Z (6 years ago)
From
QiBin Yi at IHEP, HXMT <yiqb@ihep.ac.cn>
Q. B. Yi, S. Xiao, Q. Luo, C. Cai, C. K. Li,
X. B. Li, G. Li, J. Y. Liao, S. L. Xiong,
C. Z. Liu, X. F. Li, Z. W. Li, Z. Chang, X. F. Lu,
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,
M. Wu, Y. P. Xu, S. N. Zhang (IHEP),
report on behalf of the Insight-HXMT team:
At 2019-05-31T20:10:12.00 (T0), Insight-HXMT/HE detected
GRB 190531B (trigger ID: HEB190531840) in a routine search of the data,
which was also triggered by Fermi/GBM (GCN #24695) and Fermi/LAT
(GCN #24701).
The Insight-HXMT/HE light curve mainly consists of multiple
pulses with a duration (T90) of 27.82 s measured from T0+7.93 s.
The 1-ms peak rate, measured from T0+31.40 s, is 13079 cnts/sec.
The total counts from this burst is 91598 counts.
URL_LC: http://www.hxmt.org/images/GRB/HEB190531840_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 (deposited 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.
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.
GCN Circular 24711
Subject
GRB 190531B: VLT optical upper limit
Date
2019-06-01T20:38:26Z (6 years ago)
From
Jure Japelj at API,U of Amsterdam <japelj.jure@gmail.com>
J. Japelj (U. Amsterdam), A. Rossi (INAF-OAS), D. B. Malesani
(DTU Space), K. E. Heintz (Univ. Iceland), G. Pugliese, L. Kaper
(U. Amsterdam) report on behalf of the Stargate collaboration:
We observed the field of GRB 190531B (Fermi GBM team, GCN 24695;
Kunzweiler et al., GCN 24696; Axelsson et al., GCN 24701) with the ESO VLT
UT2 (Kueyen), using the X-shooter acquisition camera. A 3x30 s exposure
with the SDSS r filter was taken at approximate time 2019 June 1.39 UT
(0.55 days after GRB).
We do not detect any new object within the error region of the detected
X-ray afterglow (D'Avanzo et al., GCN 24706), down to a 3-sigma
limiting magnitude r > 23 AB (calibrated against nearby star at position
RA=01:37:12.696, Dec=-41:57:36.702). The closest source to the XRT error
circle is at RA=01:37:11.37, Dec=-41:57:30.73, which is 3.1 arcsec away
from the XRT location, and is thus unlikely to be related to the GRB.
We acknowledge excellent support from the observing team in Paranal,
in particular Alex Correa, Florian Rodler and Pascale Hibon.
GCN Circular 24707
Subject
GRB 190531B: MASTER optical observation
Date
2019-06-01T10:06:41Z (6 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
V. Lipunov, V.Kornilov, E.Gorbovskoy, N.Tiurina, A.Kuznetsov, I.Gorbunov,
V.Vladimirov, P.Balanutsa, D.Vlasenko, D.Zimnukhov, F.Balakin,A. Chasovnikov,
V.Topolev, V.Senik, D.Kuvshinov(Lomonosov Moscow State University, SAI, Physics Department),
D. Buckley (South African Astronomical Observatory),
R. Podesta, C. Lopez, C.Francile, F. Podesta (Observatorio Astronomico Felix Aguilar OAFA, San Juan National University),
H.Levato (Instituto de Ciencias Astronomicas, de la Tierra y del Espacio ICATE, SJNU)
R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres (The Instituto de Astrofisica de Canarias),
O. Gress, N.M. Budnev, O.Ershova, S.Yazev (Applied Physics Institute, Irkutsk State University),
V. Yurkov, A. Gabovich, Yu. Sergienko, D. Kobcev (Blagoveschensk Educational State University),
A. Tlatov, D.Dormidontov, A.V. Parhomenko (Kislovodsk Solar Station of the Pulkovo Observatory),
MASTER Global Robotic Net (Lipunov et al., 2010, Advances in Astronomy,vol.2010, 30L (http://observ.pereplet.ru)
observed Fermi GRB 190531B
(Ttrig=2019-05-31 20:10:12UT, GBM team GCN24695, Veres et al. GCN 24705;
BALROG localization RA,Dec(2000) = 27.9(+/-0.8d) -40.8(+/-0.6) Kunzweiler et al. GCN 24696, GCN 24699,
LAT localization RA,Dec= 24.37, -41.97 +-0.11d(90%) Axelsson et al. GCN24701,
Swift XRT afterglow 01h 37m 11.09s -41d 57' 30.3" +-1.6 arcsec(90%) D'Avanzo et al. GCN24706, Evans et al. 24702 )
At alert time
MASTER-SAAO: Error-Box_altitude=-15d, Sun_alt=-57d.
MASTER-OAFA: Error-Box_altitude=+15d, Sun_alt=+15d
MASTER-SAAO robotic telescope (located in South African Astronomical Observatory)
was pointed to the GRB190531A 4934 sec after notice time and 20321 sec
after trigger time at 2019-06-01 01:48:53 UT .
Error-box_alt=21deg, sun_alt=-47deg.
There is no OT at Swift XRT position with unfiltered mlim=20.6m
MASTER-OAFA robotic telescope (located in Argentina)
was pointed to the GRB190531A at 2019-06-01 08:55:19UT
Error-box_alt=34deg, sun_alt=-32deg.
There is no OT at Swift XRT position with unfiltered mlim=20.0m
Reduction will be continued.
The message may be cited.
GCN Circular 24706
Subject
GRB 190531B: Swift-XRT afterglow detection
Date
2019-06-01T07:46:50Z (6 years ago)
From
Aaron Tohuvavohu at PSU/Swift <auc444@psu.edu>
P. D'Avanzo (INAF-OAB), S. J. LaPorte (PSU), J.A. Kennea (PSU), B.
Sbarufatti (INAF-OAB/PSU), K.L. Page (U. Leicester), A.P. Beardmore (U.
Leicester), M.G. Bernadini (INAF-OAB), E. Ambrosi (INAF-IASFPA) ,
A. Tohuvavohu (PSU) and P.A. Evans (U. Leicester) report on behalf of
the Swift-XRT team:
Swift-XRT has performed follow-up observations of the
Fermi/LAT-detected burst GRB 190531B (Axelsson et al. GCN Circ. 24701),
collecting 5.0 ks of Photon Counting (PC) mode data between T0+18.2 ks
and T0+29.7 ks.
Eleven uncatalogued X-ray sources are detected, of which one ("Source
8") is above the RASS limit, and is therefore likely the GRB afterglow.
Using 1291 s of PC mode data and 1 UVOT image, we find an enhanced XRT
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 24.29620, -41.95841 which is
equivalent to:
RA (J2000): 01h 37m 11.09s
Dec(J2000): -41d 57' 30.3"
with an uncertainty of 1.6 arcsec (radius, 90% confidence). This
position is 3.4 arcmin from the Fermi/LAT position.
The light curve can be modelled with a power-law decay with a decay
index of alpha=1.0 (+/-0.3).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.20 (+0.15, -0.14). The
best-fitting absorption column is 9.1 (+1.2, -1.1) x 10^21 cm^-2, in
excess of the Galactic value of 1.8 x 10^20 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum is 4.2 x 10^-11 (9.0 x 10^-11) erg
cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 9.1 (+1.2, -1.1) x 10^21 cm^-2
Galactic foreground: 1.8 x 10^20 cm^-2
Excess significance: 12.8 sigma
Photon index: 2.20 (+0.15, -0.14)
If the light curve continues to decay with a power-law decay index of
1.0, the count rate at T+24 hours will be 0.14 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 5.9 x
10^-12 (1.3 x 10^-11) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis of the likely afterglow
are at http://www.swift.ac.uk/ToO_GRBs/00020895/Source8.php.
The results of the full analysis of the XRT observations are available
at http://www.swift.ac.uk/ToO_GRBs/00020895.
This circular is an official product of the Swift-XRT team.
GCN Circular 24705
Subject
GRB 190531B: Fermi GBM observations
Date
2019-06-01T03:39:22Z (6 years ago)
From
Peter Veres at UAH <veresp@gmail.com>
P. Veres and C. Meegan (both UAH) report on behalf of the Fermi GBM Team:
"At 20:10:12.14 UT on 31 May 2019, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 190531B (trigger 581026217 / 190531840, GCN
#24695), which was also detected by Fermi-LAT (GCN # 24701).
The GBM light curve consists of multiple peaks with a duration (T90) of
about 38.4 s (50-300 keV).
The time-averaged spectrum from T0 to T0+44.4 s is best fit by a Band
function with Epeak = 473 +/- 14 keV, alpha = -0.79 +/- 0.01, and beta =
-2.33 +/- 0.06.
The event fluence (10-1000 keV) in this time interval is (9.91 +/-
0.08)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from
T0+31.2 s in the 10-1000 keV band is 27.7 +/- 0.4 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 24702
Subject
GRB 190531B: Swift ToO observations
Date
2019-06-01T01:24:19Z (6 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 ToO observation of the Fermi/LAT GRB 190531B.
Automated analysis of the XRT data will be presented online at
http://www.swift.ac.uk/ToO_GRBs/00020895
Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. These are
not necessarily related to the Fermi/LAT event. 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 24701
Subject
GRB 190531B: Fermi-LAT detection
Date
2019-06-01T01:02:55Z (6 years ago)
From
Magnus Axelsson at Stockholm U. <magaxe@kth.se>
M. Axelsson (KTH and Stockholm Univ.), M. Arimoto (Kanazawa Univ.), D. Kocevski (NASA/MSFC) and F. Longo (Univ. and INFN Trieste) report on behalf of the Fermi-LAT team:
On May 31, 2019, Fermi-LAT detected high-energy emission from GRB 190531B, which was also detected by Fermi-GBM (trigger 581026217 / 190531840; GCN 24695).
The best LAT on-ground location is found to be
RA, Dec 24.37, -41.97 (degrees, J2000)
with an error radius of 0.11 deg (90% containment, statistical error only).
This was 25 deg from the LAT boresight at the time of the GBM trigger:
T0 = 20:10:12.14 UT.
The data from the Fermi-LAT show a significant increase in the event rate after the GBM trigger that is spatially and temporally correlated with the GBM emission with high significance.
The photon flux above 100 MeV in the time interval 0-700 s after the GBM trigger is 8.9e-6 ph/cm2/s. The highest-energy photon in this interval is a 7.0 GeV event observed at T0+325s.
The estimated photon index above 100 MeV is -2.1 +/- 0.2.
The Fermi-LAT point of contact for this burst is Francesco Longo (Francesco.Longo@ts.infn.it<mailto: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 24699
Subject
GRB 190531B: name correction re. GCN 24696
Date
2019-05-31T22:41:40Z (6 years ago)
From
Jochen Greiner at MPI <jcg@mpe.mpg.de>
F. Kunzweiler & J. Greiner (both MPE Garching)
GCN 24696 wrongly named Fermi trigger 581026217 / GRB 190531840
as GRB 190531A, but it should be GRB 190531B.
We apologize for any confusion this might have caused.
GCN Circular 24695
Subject
GRB 190531B: Fermi GBM Final Real-time Localization
Date
2019-05-31T20:21:23Z (6 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 20:10:12 UT on 31 May 2019, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 190531B (trigger 581026217.141598 / 190531840).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 20.2, Dec = -39.4 (J2000 degrees, equivalent to J2000 01h 20m, -39d 23'), with a statistical uncertainty of 1.0 degrees.
The angle from the Fermi LAT boresight is 22.0 degrees.
The skymap can be found here:
http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2019/bn190531840/quicklook/glg_skymap_all_bn190531840.png
The HEALPix FITS file, including the estimated localization systematic, can be found here:
http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2019/bn190531840/quicklook/glg_healpix_all_bn190531840.fit
The GBM light curve can be found here:
http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2019/bn190531840/quicklook/glg_lc_medres34_bn190531840.gif