GRB 191004B
GCN Circular 25947
Subject
GRB 191004B: Swift detection of a burst with an optical counterpart
Date
2019-10-04T21:43:36Z (6 years ago)
From
David Palmer at LANL <palmer@lanl.gov>
S. B. Cenko (GSFC), S. D. Barthelmy (GSFC),
A. P. Beardmore (U Leicester), A. D'Ai (INAF-IASFPA),
V. D'Elia (SSDC), J.D. Gropp (PSU), J. A. Kennea (PSU),
N. J. Klingler (PSU), N. P. M. Kuin (UCL-MSSL),
S Laha (CRESST/GSFC/UMD), A. Y. Lien (GSFC/UMBC),
F. E. Marshall (NASA/GSFC), M. J. Moss (GWU), D. M. Palmer (LANL) and
A. Tohuvavohu (Toronto) report on behalf of the Neil Gehrels Swift
Observatory Team:
At 21:33:41 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 191004B (trigger=927839). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 49.177, -39.613, which is
RA(J2000) = 03h 16m 42s
Dec(J2000) = -39d 36' 46"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve shows multiple peaks
with a total duration of about 40 sec. The peak count rate
was ~9500 counts/sec (15-350 keV), at ~3 sec after the trigger.
The XRT began observing the field at 21:34:39.3 UT, 57.7 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source located at RA, Dec 49.20403, -39.63494 which
is equivalent to:
RA(J2000) = 03h 16m 48.97s
Dec(J2000) = -39d 38' 05.8"
with an uncertainty of 3.9 arcseconds (radius, 90% containment). This
location is 108 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. No spectrum from the promptly downlinked
event data is yet available to determine the column density.
The initial flux in the 2.5 s image was 1.81e-09 erg cm^-2 s^-1 (0.2-10
keV).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 68 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
RA(J2000) = 03:16:49.10 = 49.20458
DEC(J2000) = -39:38:03.3 = -39.63425
with a 90%-confidence error radius of about 0.62 arc sec. This position is 2.9
arc sec. from the center of the XRT error circle. The estimated magnitude is
18.00 with a 1-sigma error of about 0.14. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.02.
Burst Advocate for this burst is S. B. Cenko (brad.cenko AT nasa.gov).
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/)
GCN Circular 25949
Subject
GRB 191004B: Optical Afterglow Detection with LCO
Date
2019-10-04T23:55:39Z (6 years ago)
From
Robert Strausbaugh at U. of the Virgin Islands <robert.strausbaugh@uvi.edu>
R. Strausbaugh (U. of the Virgin Islands), A. Cucchiara (U. of the Virgin Islands/College of Marin) report on behalf of a larger collaboration:
We observed Swift GRB 191004B (Palmer et al., GCN 25947) with
the LCO 1-m Sinistro instrument on September 4, from 21:50 to 22:07 UT
(corresponding to 0.11 to 0.4 hours from the GRB trigger time)
with the Bessel R filter.
We performed a series of 5x180s exposures, and we detect a source not present in either USNO-B1.0 or 2MASS surveys consistent with the optical afterglow location (Palmer et al., GCN 25947
) with the following magnitude:
R = 18.07 +/- 0.02
This flux is calibrated against several USNO-B1.0 objects near the GRB location but is not corrected for Galactic Extinction.
These observations were possible thanks to the USVI NASA-EPSCoR
Research Infrastructure Development (RID) grant NNX16AL44A.
GCN Circular 25951
Subject
GRB 191004B: Enhanced Swift-XRT position
Date
2019-10-05T01:36:47Z (6 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester)
report on behalf of the Swift-XRT team.
Using 162 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 191004B, 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 = 49.20398, -39.63502 which is equivalent
to:
RA (J2000): 03h 16m 48.96s
Dec (J2000): -39d 38' 06.1"
with an uncertainty of 2.0 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 25954
Subject
GRB 191004B: NOT optical photometry
Date
2019-10-05T03:58:45Z (6 years ago)
From
Kasper Elm Heintz at Univ. of Iceland and DAWN/NBI <keh14@hi.is>
K. E. Heintz (Univ. of Iceland), D. B. Malesani (DTU space), and S. Moran (NOT), report on behalf of a larger collaboration:
We observed the field of the Swift-detected GRB 191004B (Cenko et al., GCN 25947) with the Nordic Optical Telescope (NOT) equipped with StanCAM. We obtained 3x300s exposures with the Bessel R filter starting at 02:30:07 UT on October 5 (i.e. 4.94 hr post-burst). We clearly detect the optical afterglow (Cenko et al., GCN 25947; Lipunov et al., GCN 25948; Strausbaugh & Cucchiara, GCN 25949) and measure a magnitude of R = 20.87 +/- 0.05 mag in the stacked image. We calibrated the photometry assuming for the USNO star at (RA, Dec) = (03:16:54.39, -39:37:41.5) a magnitude of R = 16.97 mag. The derived magnitude for the GRB afterglow is not corrected for the Galactic extinction.
GCN Circular 25955
Subject
GRB 191004B: Swift-BAT refined analysis
Date
2019-10-05T04:07:48Z (6 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@milkyway.gsfc.nasa.gov>
M. Stamatikos (OSU), S. D. Barthelmy (GSFC), S. B. Cenko (GSFC),
J. R. Cummings (CPI), H. A. Krimm (NSF), S. Laha (GSFC/UMBC),
A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Sakamoto (AGU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
Using the data set from T-60 to T+243 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 191004B (trigger #927839)
(Cenko, et al., GCN Circ. 25947). The BAT ground-calculated position is
RA, Dec = 49.200, -39.637 deg, which is
RA(J2000) = 03h 16m 47.9s
Dec(J2000) = -39d 38' 15.0"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 97%.
The mask-weighted light curve shows multiple overlapping peaks starting at
T-1 sec, peaking at ~T+7 sec, and ending at ~T+45 sec.
T90 (15-350 keV) is 37.7 +- 14.9 sec (estimated error including systematics).
The time-averaged spectrum from T-1.45 to T+56.17 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.10 +- 0.08. The fluence in the 15-150 keV band is 2.5 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+2.75 sec in the 15-150 keV band
is 5.0 +- 0.2 ph/cm2/sec. 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/927839/BA/
GCN Circular 25956
Subject
GRB 191004B: VLT/X-shooter redshift
Date
2019-10-05T08:40:16Z (6 years ago)
From
Valerio D'Elia at ASDC <valerio.delia@ssdc.asi.it>
V. D'Elia (SSDC), J. P. U. Fynbo (DAWN/NBI), L. Izzo (DARK/NBI), D. B. Malesani (DTU Space), K. E. Heintz (Univ. of Iceland), N. R. Tanvir (Univ. Leicester), A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), S. D. Vergani (CNRS -GEPI/Observatorie de Paris) report on behalf of the Stargate collabaration:
We observed the optical afterglow (Lipunov et al., GCN 25948, Strausbaugh et al., GCN 25949) of the Swift/BAT GRB 191004B (Cenko et al., GCN 25947) using the ESO VLT UT2 (Kueyen) equipped with the X-shooter spectrograph. Our spectra cover the wavelength range 3000-21000 AA, and consist of 6 exposures by 600 s each. The observation mid time was 2019 Oct 05 at about 5:30 UT (8 hr after the GRB).
In a 30 s image taken with the acquisition camera on Oct 05.1989 UT, we detect the optical afterglow, for which we measure a magnitude r = 21.23 +- 0.03 AB (calibrated against nearby stars from the SkyMapper catalog; Wolf et al. 2018, PASA, 35, 010; https:doi.org/10.4225/41/593620ad5b574).
We clearly detect continuum over the full covered wavelength range. A strong absorption is visible around 5474 AA, and an emission feature at 5479 AA, which we identify as due to H I. This is confirmed by the presence of the Ly alpha forest blueward of this wavelength. We also detect other narrower absorption features which we interpret as due to e.g. C IV and Si IV at a common redshift z = 3.503. The continuum is well detected down to ~800 AA rest frame, i.e, below the Lyman limit.
We also detect an intervening absorber (Mg II, Fe II) at z=2.137
We acknowledge excellent support from the ESO observing staff in Paranal, in particular Camila Navarrete and Bin Yang.
GCN Circular 25958
Subject
GRB 191004B: COATLI Optical Observations
Date
2019-10-06T03:15:25Z (6 years ago)
From
Alan M Watson at UNAM <alan@astro.unam.mx>
Alan M. Watson (UNAM), Nat Butler (ASU), Rosa L. Becerra (UNAM), Diego Gonz��lez
(UNAM), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Margarita Pereyra
(UNAM), and Eleonora Troja (GSFC) report:
We observed the field of GRB 191004B (Cenko et al., GCN Circ. 25947) with the
COATLI 50-cm telescope and interim imager at the Observatorio Astron��mico
Nacional on the Sierra de San Pedro M��rtir (http://coatli.astroscu.unam.mx) from
2019-10-05 06:54 to 12:11, obtaining a total of 1.65 hours of exposure in the w
filter.
At the position of the bright afterglow detected by Swift/UVOT (Cenko et al.,
GCN Circ. 25947), we detect a source with w = 21.47 +/- 0.17.
Our w magnitudes are calibrated against the Pan-STARRS1 catalog, are on an
approximate AB system (Becerra et al., 2019, ApJ, 872, 118), and are not
corrected for Galactic extinction in the direction of the GRB.
We thank the COATLI technical team and the staff of the Observatorio Astron��mico
Nacional.
GCN Circular 25960
Subject
GRB 191004B: GROND Detection of the Optical/NIR Afterglow
Date
2019-10-06T10:24:52Z (6 years ago)
From
Patricia Schady at Swift <p.schady@bath.ac.uk>
P. Schady (Univ. of Bath), J. Bolmer (MPE Garching), and A. Nicuesa Guelbenzu (TLS Tautenburg) report:
We observed the field of GRB 191004B (Swift trigger 927839; Cenko et al., GCN #25947) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPG telescope at ESO La Silla Observatory (Chile).
Observations started at 02:25 UT on 5th October, 4.9 hours after the GRB trigger. They were performed at an average seeing of 1.5" and at an average airmass of 1.8.
We detect a single point source consistent with the position of the Swift-XRT and MASTER afterglow (Beardmore et al., GCN # 25951; Lipunov et al., GCN # 25948) in all optical and NIR bands apart from K. In an 8 min exposure, we measure an AB magnitude in the r� band filter of r' = 20.86 +/- 0.04 mag.
The optical and NIR afterglow is still clearly detected in a second epoch of observations taken on the night of 6th October, with an AB magnitude r' = 22.10 +/- 0.03 mag.
The above magnitudes are calibrated again sky-mapper, and not corrected for the expected Galactic foreground extinction corresponding to a reddening of E_(B-V)=0.01 in the direction of the burst (Schlafly & Finkbeiner 2011).
We acknowledge the excellent support from Regis Lachaume in La Silla in acquiring these observations.
[GCN OPS NOTE(29apr20): Per D.A.Kann, the spelling of the "Balmer" author was changed to "Bolmer".]
GCN Circular 25961
Subject
GRB 191004B: Swift-XRT refined Analysis
Date
2019-10-06T12:41:44Z (6 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
A. Tohuvavohu (U. Toronto), J.P. Osborne (U. Leicester), K.L. Page (U.
Leicester), E. Ambrosi (INAF-IASFPA) , M. Capalbi (INAF-IASFPA), M.
Perri (ASDC), J.A. Kennea (PSU), B. Sbarufatti (PSU),
and S.B. Cenko report on behalf of the Swift-XRT team:
We have analysed 8.6 ks of XRT data for GRB 191004B (Cenko et al. GCN
Circ. 25947), from 63 s to 102.9 ks after the BAT trigger. The data
comprise 142 s in Windowed Timing (WT) mode with the remainder in
Photon Counting (PC) mode. The enhanced XRT position for this burst was
given by Beardmore et al. (GCN Circ. 25951).
The light curve can be modelled with an initial power-law decay with an
index of alpha=2.9 (+0.6, -0.7), followed by a break at T+94.6 s to an
alpha of 1.073 (+0.031, -0.027).
A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.75 (+0.09, -0.07). The
best-fitting absorption column is 1.4 (+6.8, -1.4) x 10^21 cm^-2, at a
redshift of 3.503, in addition to the Galactic value of 1.9 x 10^20
cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index
of 1.54 (+0.21, -0.14) and a best-fitting absorption column of 2 (+178,
-2) x 10^20 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux
conversion factor deduced from this spectrum is 4.2 x 10^-11 (4.3 x
10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Galactic foreground: 1.9 x 10^20 cm^-2
Intrinsic column: 2 (+178, -2) x 10^20 cm^-2 at z=3.503
Photon index: 1.54 (+0.21, -0.14)
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00927839.
This circular is an official product of the Swift-XRT team.
GCN Circular 25974
Subject
Konus-Wind observation of GRB 191004B
Date
2019-10-07T18:00:56Z (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 191004B
(Swift-BAT detection: Cenko et al., GCN circ. 25947;
Stamatikos et al., GCN circ. 25955)
triggered Konus-Wind at T0=77626.99 s UT (21:33:46.990).
The burst light curve shows a multi-peaked structure
which starts at ~T0-0.5 s and has a total duration of ~5.5 s.
The emission is seen up to ~1 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB191004_T77626/
As observed by Konus-Wind, the burst
had a fluence of 4.13(-0.40,+0.45)x10^-6 erg/cm2,
and a 64-ms peak flux, measured from T0+3.504 s,
of 2.56(-0.73,+0.74)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the burst
(measured from T0 to T0+8.448 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 = -0.51(-0.30,+0.34)
and Ep = 172(-21,+27) keV (chi2 = 59/57 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -3.0
(chi2 = 59/56 dof).
Assuming the redshift z=1.260 (D'Elia et al., GCN circ. 25956)
and a standard cosmology model with H_0 = 67.3 km/s/Mpc,
Omega_M = 0.315, and Omega_Lambda = 0.685 (Planck Collaboration, 2014),
we estimate the following rest-frame parameters:
the isotropic energy release E_iso is 1.79(-0.17,+0.20)x10^52 erg,
the peak luminosity L_iso is 2.51(-0.72,+0.73)x10^52 erg/s,
and the rest-frame peak energy of the time-integrated spectrum,
Ep,i, is 389(-47,+61) keV.
With these energetics, the burst lies within the 90% prediction bands
for both 'Amati' and 'Yonetoku' relations built for the sample
of 138 long KW GRBs with known redshifts
(Tsvetkova et al., ApJ 850 161, 2017).
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.
GCN Circular 25976
Subject
GRB 191004B: Correction to Konus-Wind GCN 25974
Date
2019-10-07T19:14:38Z (6 years ago)
From
Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>
D. Svinkin reports on behalf of the Konus-Wind team:
The redshift of GRB 191004B mentioned in GCN 25974 was incorrect,
the correct one is z = 3.503 (D'Elia et al., GCN circ. 25956).
Thus, assuming the redshift z=3.503 and a standard cosmology model with
H_0 = 67.3 km/s/Mpc, Omega_M = 0.315, and Omega_Lambda = 0.685
(Planck Collaboration, 2014),
we estimate the following rest-frame parameters:
the isotropic energy release E_iso is 1.08(-0.10,+0.12)x10^53 erg,
the peak luminosity L_iso is 3.01(-0.86,+0.87)x10^53 erg/s,
and the rest-frame peak energy of the time-integrated spectrum,
Ep,i, is 775(-95,+122) keV.
With these energetics, the burst lies within the 68% prediction bands
for both 'Amati' and 'Yonetoku' relations built for the sample
of 138 long KW GRBs with known redshifts
(Tsvetkova et al., ApJ 850 161, 2017).
I apologize for possible inconvenience.
GCN Circular 25977
Subject
GRB 191004B: Continued Optical Afterglow Monitoring with LCO
Date
2019-10-07T20:11:14Z (6 years ago)
From
Robert Strausbaugh at U. of the Virgin Islands <robert.strausbaugh@uvi.edu>
R. Strausbaugh (U. of the Virgin Islands), A. Cucchiara (U. of the Virgin Islands/College of Marin) report on behalf of a larger collaboration:
We obtained a second epoch (first epoch, GCN 25949) of Swift GRB 191004B (Palmer et al., GCN 25947) data with
the LCO 1-m Sinistro instrument at the Sutherland Site (SAAO) on September 5, from 2:40 to 3:03 UT
(corresponding to 4.95 to 5.3 hours from the GRB trigger time)
with the Bessel R and I filters.
We performed a series of 5x240s exposures, and we detect the afterglow with the following magnitudes:
R = 21.01 +/- 0.08
I = 19.91 +/- 0.08
This flux is calibrated against several USNO-B1.0 objects near the GRB location but is not corrected for Galactic Extinction.
These observations were possible thanks to the USVI NASA-EPSCoR
Research Infrastructure Development (RID) grant NNX16AL44A.
GCN Circular 25978
Subject
GRB 191004B: Swift/UVOT Detection
Date
2019-10-07T20:45:09Z (6 years ago)
From
Sam LaPorte at PSU <sjl5346@psu.edu>
GRB 191004B: Swift/UVOT Detection
S. J. LaPorte (PSU) and S. B. Cenko (GSFC)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 191004B
69 s after the BAT trigger (Cenko et al., GCN Circ. 25947).
A fading source consistent with the XRT position
(Beardmore et al. GCN Circ. 25951)
is detected in the initial UVOT exposures.
The preliminary UVOT position is:
RA (J2000) = 03:16:49.10 = 49.20459 (deg.)
Dec (J2000) = -39:38:03.9 = -39.63441 (deg.)
with an estimated uncertainty of 0.43 arc sec. (radius, 90% confidence),
consistent with the positions reported by LCO (Strausbaugh et al. GCN Circ.
25949),
NOT (Heintz et al. GCN Circ. 25954), VLT/X-Shooter (D'Elia et al. GCN Circ.
25956),
COATLI (Watson et al. GCN Circ. 25958), and GROND (Schady et al. GCN Circ.
25960).
Preliminary detections and 3-sigma upper limits using the UVOT photometric
system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures
are:
Filter T_start(s) T_stop(s) Exp(s) Mag
b 38697 38997 295 >20.42
uvm2 44827 45727 885 >20.25
u 294 387 91 >19.04
v 43916 44822 885 >20.07
uvw1 45734 46281 538 >19.96
uvw2 39915 40544 618 >20.09
white 82 232 147
18.01+-0.05
white 39003 39909 885 20.51+-0.13
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).