GRB 150403A
GCN Circular 17665
Subject
GRB 150403A: Swift detection of a burst with an optical counterpart
Date
2015-04-03T22:17:05Z (10 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@milkyway.gsfc.nasa.gov>
A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (GSFC), V. D'Elia (ASDC),
N. Gehrels (NASA/GSFC), J. A. Kennea (PSU),
F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester) and
B. Sbarufatti (INAF-OAB/PSU) report on behalf of the Swift Team:
At 21:54:16 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 150403A (trigger=637044). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 311.505, -62.702, which is
RA(J2000) = 20h 46m 01s
Dec(J2000) = -62d 42' 04"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve shows two overlapping peaks
with a total duration of about 60 sec. The peak count rate
was ~19,000 counts/sec (15-350 keV), at ~7 sec after the trigger.
The XRT began observing the field at 21:55:31.5 UT, 74.7 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 311.5019, -62.7118 which is equivalent to:
RA(J2000) = +20h 46m 0.46s
Dec(J2000) = -62d 42' 42.5"
with an uncertainty of 4.8 arcseconds (radius, 90% containment). This
location is 35 arcseconds from the BAT onboard position, within the BAT
error circle. No event data are yet available to determine the column
density using X-ray spectroscopy.
The initial flux in the 2.5 s image was 6.34e-09 erg cm^-2 s^-1 (0.2-10
keV).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 84 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
RA(J2000) = 20:46:01.14 = 311.50476
DEC(J2000) = -62:42:41.0 = -62.71138
with a 90%-confidence error radius of about 0.61 arc sec. This position is 5.0
arc sec. from the center of the XRT error circle. The estimated magnitude is
14.85 with a 1-sigma error of about 0.14. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.05.
Burst Advocate for this burst is A. Y. Lien (amy.y.lien 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/too.html.)
GCN Circular 17666
Subject
GRB 150403A: Enhanced Swift-XRT position
Date
2015-04-04T09:28:12Z (10 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 3056 s of XRT Photon Counting mode data and 5 UVOT
images for GRB 150403A, 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 = 311.50504, -62.71106 which is equivalent
to:
RA (J2000): 20h 46m 1.21s
Dec (J2000): -62d 42' 39.8"
with an uncertainty of 1.4 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 17667
Subject
GRB 150403A: Fermi-LAT detection
Date
2015-04-04T10:12:54Z (10 years ago)
From
Elisabetta Bissaldi at U.Innsbruk/IAPP <Elisabetta.Bissaldi@uibk.ac.at>
F. Longo (University & INFN Trieste), E. Bissaldi (INFN Bari),
M. Arimoto (Tokyo Tech) and S. Zhu (UMD, USA)
report on behalf of the Fermi-LAT team:
At 21:54:10.95 on April 03, 2015, Fermi-LAT detected
high-energy emission from GRB 150403A, which was also
detected by Fermi-GBM (trigger 449790853/150403913)
and Swift (Lien at al, GCN 17665).
The GBM location was initially inside the LAT field
of view at an angle of ~55 degrees to the LAT boresight
and triggered an autonomous repoint of the spacecraft.
The best LAT on-ground location is found to be
RA, Dec (J2000) 311.79, -62.76
with an error radius of 0.50 deg (95% containment,
statistical error only) and consistent with the
enhanced Swift/XRT location (Beardmore et al, GCN 17666).
The data from the Fermi-LAT show a significant increase
in the event rate within 12 degrees of the Swift/XRT
location after the trigger.
More than 30 photons above 100 MeV are observed
within 2000 seconds. The highest-energy photon is a
5 GeV event which is observed 630 s after the GBM trigger.
Using the LAT Low Energy (LLE) data selection, over 200 counts
above background are detected within a 20 s interval coincident
with the time of the GBM emission.
The Fermi-LAT point of contact for this burst is
Sylvia Zhu (sjzhu@umd.edu).
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 17668
Subject
GRB 150403A: Swift-XRT refined Analysis
Date
2015-04-04T10:17:03Z (10 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
D.N. Burrows (PSU), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU),
A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), A.
Amaral-Rogers (U. Leicester), A. Maselli (INAF-IASFPA), A. Melandri
(INAF-OAB), P. D'Avanzo (INAF-OAB) and A.Y. Lien report on behalf of
the Swift-XRT team:
We have analysed 10 ks of XRT data for GRB 150403A (Lien et al. GCN
Circ. 17665), from 64 s to 30.5 ks after the BAT trigger. The data
comprise 3.5 ks in Windowed Timing (WT) mode (the first 8 s were taken
while Swift was slewing) with the remainder in Photon Counting (PC)
mode. The enhanced XRT position for this burst was given by Beardmore
et al. (GCN Circ. 17666).
The late-time light curve (from T0+5.1 ks) can be modelled with a
series of power-law decays. The initial decay index is alpha=1.14
(+0.08, -0.15). At T+6776 s the decay steepens to an alpha of 8.0
(+0.0, -2.7) before breaking again at T+7063 s to a final decay with
index alpha=1.42 (+0.14, -0.22).
A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.695 (+/-0.016). The
best-fitting absorption column is 1.03 (+/-0.05) x 10^21 cm^-2, in
excess of the Galactic value of 5.3 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.66 (+/-0.10) and a
best-fitting absorption column of 1.1 (+/-0.3) x 10^21 cm^-2. The
counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum is 4.1 x 10^-11 (4.7 x 10^-11) erg cm^-2
count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 1.1 (+/-0.3) x 10^21 cm^-2
Galactic foreground: 5.3 x 10^20 cm^-2
Excess significance: 2.9 sigma
Photon index: 1.66 (+/-0.10)
If the light curve continues to decay with a power-law decay index of
1.42, the count rate at T+24 hours will be 0.16 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 6.7 x
10^-12 (7.7 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/00637044.
This circular is an official product of the Swift-XRT team.
GCN Circular 17672
Subject
GRB 150403A: VLT/X-shooter redshift
Date
2015-04-04T12:06:05Z (10 years ago)
From
Dong Xu at DARK/NBI <dong.dark@gmail.com>
V. Pugliese (API/Uva), D. Xu (DARK/NBI), N. R. Tanvir, K. Wiersema (U.
Leicester), J. P. U. Fynbo, B. Milvang-Jensen (DARK/NBI), V. D'Elia
(ASI/ASDC and INAF/Roma) report on behalf of a larger collaboration:
We observed the afterglow of GRB 150403A (Lien et al. GCN 17665; Longo
et al. GCN 17667) with X-shooter at the Very Large Telescope (Paranal
Observatory, Chile). Observations started at 08:44:48 UT on 2015-04-04
(i.e., 10.84 hr after the burst), and consisted of photometry in V-,
r-, z-, and g- bands as well as spectroscopy of 4x600 s exposures
covering the spectral range between 3000 and 25000 AA, equipped with
UVB/VIS/NIR arms.
The optical afterglow is well detected in each photometric image, and
has m(R) ~ 19.1 mag at 10.85 hr post-burst, calibrated with nearby
USNO B1 stars. For the spectroscopy, prominent absorption lines are
detected in a continuum throughout the arms. In a preliminary
reduction we detect absorption features of SII, SiIV, OI, SiII, SiII*,
CII, CII*, CIV, AlII, NiII*, FeII, FeII*, MnI, MgII, MgI at a common
redshift of z = 2.06, which is consistent with a broad Lya trough at
the same redshift. We suggest this is the redshift of the GRB.
We also detect an intervening system at z=1.76, identified with
absorption lines of SiII, CIV, AlII, and so on.
We acknowledge the excellent support provided by Paranal staff, and in
particular Andrea Mehner, and Emanuela Pompei.
GCN Circular 17673
Subject
GRB 150403A: Swift/UVOT Detection
Date
2015-04-04T13:51:07Z (10 years ago)
From
Paul Kuin at MSSL <npkuin@gmail.com>
N. P. M. Kuin (UCL-MSSL) and A. Y. Lien (GSFC/UMBC) report on behalf
of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 150403A
85 s after the BAT trigger (Lien et al., GCN Circ. 17665). A source
consistent with the XRT position (Beardmore et al. GCN Circ. 17666)
is detected in the initial UVOT exposures.
The preliminary UVOT position is:
RA (J2000) = 20:46:01.15 = 311.50479 (deg.)
Dec (J2000) = -62:42:41.0 = -62.71139 (deg.)
with an estimated uncertainty of 0.42 arc sec. (radius, 90% confidence).
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
white 85 235 147 14.89 +/- 0.02
v 627 647 20 16.49 +/- 0.13
b 553 573 20 16.65 +/- 0.08
u 298 547 246 16.14 +/- 0.03
w1 676 5286 294 19.68 +/- 0.21
m2 6317 23414 1178 >22.2
w2 5907 7536 387 >20.6
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.05 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 17674
Subject
GRB 150403A: Fermi GBM Detection
Date
2015-04-04T14:04:39Z (10 years ago)
From
Binbin Zhang at UAH <binbin.zhang@uah.edu>
Bin-Bin Zhang (UAH) reports on behalf of the Fermi GBM Team:
"At 21:54:10.95 UT on 03 April 2015, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 150403A (trigger 449790853 / 150403913),
which was also detected by the Swift (Lien et al. 2015, GCN 17665)
and Fermi LAT (Longo et al. 2015, GCN 17667). The GBM on-ground
location is consistent with the Swift position. The trigger resulted
in an Autonomous Repoint Request (ARR) that was accepted and the
spacecraft slewed to the GBM in-flight location. The initial angle
from the Fermi LAT boresight is about 55 degrees.
The GBM light curve shows a bright single pulse with a duration (T90)
of about 22.3 s (50-300 keV). The time-averaged spectrum from
T0+3.3 s to T0+25.6 s is best fit by a Band function with
Epeak = 311 +/- 14 keV, alpha = -0.72 +/- 0.02, and beta = -1.85 +/- 0.03.
The event fluence (10-1000 keV) in this time interval is
(5.73 +/- 0.05)E-05 erg/cm^2. The 1.024-sec peak photon flux
measured starting from T0+11.1 s in the 10-1000 keV band
is 33.5 +/- 0.5 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."
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GCN Circular 17675
Subject
GRB 150403A: Swift-BAT refined analysis
Date
2015-04-04T18:40:14Z (10 years ago)
From
Amy Lien at GSFC <amy.y.lien@nasa.gov>
T. Sakamoto (AGU), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA),
A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL),
M. Stamatikos (OSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
Using the data set from T-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 150403A (trigger #637044)
(Lien, et al., GCN Circ. 17665). The BAT ground-calculated position is
RA, Dec = 311.505, -62.706 deg which is
RA(J2000) = 20h 46m 01.1s
Dec(J2000) = -62d 42' 20.5"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 40%.
The mask-weighted light curve shows a single bright peak. The main structure
starts at ~ T-10 s, peaks at ~ T+6 s, and ends at ~ T+35 s. There are some
weaker emissions that starts at ~ T-170 s and lasts till ~ T+195 s. T90 (15-350 keV)
is 40.90 +- 11.72 sec (estimated error including systematics).
The time-averaged spectrum from T-83.15 to T+145.37 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.23 +- 0.04. The fluence in the 15-150 keV band is 1.7 +- 0.03 x 10^-5 erg/cm2.
The 1-sec peak photon flux measured from T+5.80 sec in the 15-150 keV band
is 17.6 +- 0.6 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/637044/BA/
GCN Circular 17677
Subject
Konus-Wind observation of GRB 150403A
Date
2015-04-05T12:02:58Z (10 years ago)
From
Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru>
S. Golenetskii, R.Aptekar, D. Frederiks, V. Pal'shin, P. Oleynik,
M. Ulanov, D. Svinkin, A. Tsvetkova, A.Lysenko, and T. Cline
on behalf of the Konus-Wind team, report:
The long-duration, intense GRB 150403A
(Swift-BAT trigger #637044: Lien et al., GCN 17665;
Sakamoto et al., GCN 17675;
Fermi-LAT detection: Longo et al., GCN 17667;
Fermi-GBM detection: Zhang, GCN 17674)
triggered Konus-Wind at T0=78852.693 s UT (21:54:12.693).
The KW light curve shows a single bright pulse with a duration of ~26 s.
The emission is visible up to ~10 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB150403_T78852/
As observed by Konus-Wind, the burst had a fluence
of 1.0(-0.1,+0.1)x10^-4 erg/cm2, and a 64-ms peak flux,
measured from T0+9.088 s, of 1.7(-0.1,+0.1)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum (measured from T0 to T0+27.136 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.93 (-0.07,+0.08),
the high energy photon index beta = -2.06 (-0.12,+0.08),
the peak energy Ep = 373 (-48,+58) keV,
chi2 = 124/97 dof.
The spectrum near the peak count rate
(measured from T0+7.168 to T0+10.752 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.78 (-0.08,+0.10),
the high energy photon index beta = -2.13 (-0.12,+0.09),
the peak energy Ep = 430 (-57,+64) keV,
chi2 = 117/97 dof.
Assuming the redshift z=2.06 (Pugliese et al., GCN 17672)
and a standard cosmology model with H_0 = 70 km/s/Mpc,
Omega_M = 0.27, and Omega_Lambda = 0.73,
we estimate the following rest-frame parameters:
the isotropic energy release E_iso is ~1.0x10^54 erg,
the peak luminosity L_iso is ~5.3x10^53 erg/s,
and the rest-frame peak energy of the time-integrated spectrum,
Ep,i, is ~1320 keV.
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.
GCN Circular 17680
Subject
GRB 150403A: MASTER-net optical observation
Date
2015-04-06T17:24:35Z (10 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
E. Gorbovskoy, V. Lipunov, N.Tyurina, V.Kornilov,
P.Balanutsa, A.Kuznetsov, D.Kuvshinov,
Lomonosov Moscow State University, Sternberg Astronomical Institute
D.Buckley, S. Potter, A.Kniazev, M.Kotze
South African Astronomical Observatory
K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk
Irkutsk State University
A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik
Kislovodsk Solar Station of the Pulkovo Observatory
V.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov
Blagoveschensk Educational State University, Blagoveschensk
V.Krushinski, I.Zalozhnih, A. Popov
Ural Federal University, Kourovka
Hugo Levato and Carlos Saffe
Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)
Claudio Mallamaci, Carlos Lopez and Federico Podest
Observatorio Astronomico Felix Aguilar (OAFA)
MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru)
located in SAAO was pointed to the GRB150403A (Lien et al. GCN 17665)
20418 sec after notice time and 20434 sec (5.7h) after trigger time at
2015-04-04 03:34:51 UT immediately after suitable weather condition came,
in automatic mode. Observation lasted about 30 minutes, until the weather
became bad again. We detect a faint OT on a Swift UVOT position (Kuin et al. GCN17673).
The estimated unfiltered magnitude is:
Date time_start T0-Tmid[s] Expt.[s] Mag Coadd
2015-04-04 03:34:51.49 20840 720 19.2 4
Our unfiltered band is well described by a parity 0.8R+0.2B (USNO B1).
The message may be cited.