GRB 150301B
GCN Circular 17515
Subject
GRB 150301B: Swift detection of a burst with an optical afterglow
Date
2015-03-01T19:50:01Z (10 years ago)
From
David Palmer at LANL <palmer@lanl.gov>
A. Y. Lien (GSFC/UMBC), D. N. Burrows (PSU), M. M. Chester (PSU),
J. R. Cummings (NASA/UMBC), M. De Pasquale (INAF-IASFPA),
A. Maselli (INAF-IASFPA), K. L. Page (U Leicester),
D. M. Palmer (LANL) and M. H. Siegel (PSU) report on behalf of the
Swift Team:
At 19:38:04 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 150301B (trigger=633180). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 89.157, -57.977 which is
RA(J2000) = 05h 56m 38s
Dec(J2000) = -57d 58' 37"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a single-peaked
structure with a duration of about 20 sec. The peak count rate
was ~4000 counts/sec (15-350 keV), at ~1 sec after the trigger.
The XRT began observing the field at 19:39:26.4 UT, 82.4 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 89.16636, -57.97051 which is equivalent
to:
RA(J2000) = 05h 56m 39.93s
Dec(J2000) = -57d 58' 13.8"
with an uncertainty of 3.6 arcseconds (radius, 90% containment). This
location is 29 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.
A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density consistent with the Galactic value of 6.16
x 10^20 cm^-2 (Willingale et al. 2013).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 85 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
RA(J2000) = 05:56:39.86 = 89.16608
DEC(J2000) = -57:58:10.4 = -57.96956
with a 90%-confidence error radius of about 0.61 arc sec. This position is 31.9
arc sec. from the center of the BAT error circle. The estimated magnitude is
16.22 with a 1-sigma error of about 0.14. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.08.
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 17518
Subject
GRB 150301B: MASTER early OT detection
Date
2015-03-01T20:51:41Z (10 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
D.Buckley, S. Potter, A.Kniazev, M.Kotze
South African Astronomical Observatory
E. Gorbovskoy, V. Lipunov, V.Kornilov,
N.Tyurina, P.Balanutsa, A.Kuznetsov, V.V.Chazov, D.Kuvshinov,
Lomonosov Moscow State University,
Sternberg Astronomical Institute, Moscow State University
V.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov
Blagoveschensk Educational State University, Blagoveschensk
A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik
Kislovodsk Solar Station of the Pulkovo Observatory
V.Krushinsky, I.Zalozhnih, A. Popov
Ural Federal University, Yekaterinburg, 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 GRB150301.82 (Lien et al, GCN 17515)
60 sec after notice time
and 79 sec after trigger time at 2015-03-01 19:39:23 UT in two
polarizations. On our first (10s
exposure) set we found 1 optical transient within SWIFT error-box (ra=05
56 37 dec=-57 58 35 r=0.050000).
T_start RA DEC Exp unfiltered
s magnitude
2015-03-01 19:39:23 79.0 05h 56m 39.94s -57d 58m 10.0s 15.3
The error is about 0.5 arcsec. This position is coincidet with UVOT data.
We detected OT before maximum brightness.
The 5-sigma upper limit has been about 16.8 mag . The telegram is
generated automatically.
We have number of the images after maximum in two polarizations. The
reduction is continuated.
The message may be cited.
GCN Circular 17520
Subject
GRB 150301B: Enhanced Swift-XRT position
Date
2015-03-01T22:44:01Z (10 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 386 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 150301B, 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 = 89.16660, -57.96950 which is equivalent
to:
RA (J2000): 05h 56m 39.98s
Dec (J2000): -57d 58' 10.2"
with an uncertainty of 1.8 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 17522
Subject
GRB 150301B: GROND afterglow observations
Date
2015-03-02T01:55:37Z (10 years ago)
From
Alexander Kann at TLS Tautenburg <kann@tls-tautenburg.de>
D. A. Kann (TLS Tautenburg), C. Delvaux and J. Greiner (both MPE Garching)
report on behalf of the GROND team:
We observed the field of GRB 150301B (Swift trigger 633180; Lien et al.,
GCN #17515) 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 00:09 UT on 2015-03-02, 4.5 hrs after the GRB
trigger. They were performed at an average seeing of 1".0 and at an
average airmass of 1.1.
We detect the optical afterglow candidate reported by Lien et al. (GCN
#17515) and Buckley et al. (GCN #17518).
Based on 7.7 min of total exposure time in g'r'i'z' and 8.0 min in JHK,
centered 5 hrs after the GRB, we estimate the following preliminary
magnitudes (all in AB system):
g' = 21.7 +/- 0.2 mag,
r' = 21.4 +/- 0.1 mag,
i' = 21.2 +/- 0.1 mag,
z' = 21.0 +/- 0.1 mag,
J = 20.5 +/- 0.3 mag,
H = 20.6 +/- 0.4 mag, and
K > 17.9 mag.
Given magnitudes are calibrated against GROND zeropoints (g'r'i'z') as
well as 2MASS field stars and are not corrected for the expected Galactic
foreground extinction corresponding to a reddening of E_(B-V)=0.08 mag in
the direction of the burst (Schlegel et al. 1998).
GCN Circular 17523
Subject
GRB 150301B: X-shooter spectroscopy
Date
2015-03-02T02:07:10Z (10 years ago)
From
Antonio de Ugarte Postigo at IAA-CSIC <deugarte@iaa.es>
A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), T. Kruehler (ESO),
H. Flores (GEPI/Obs. de Paris), and J.P.U. Fynbo (DARK/NBI)
report on behalf of a larger collaboration:
We observed the afterglow of GRB 150301B (Lien et al. GCN 17515,
Buckley et al. GCN 17518, Kann et al. GCN 17522) with X-shooter at the
Very Large Telescope (Paranal Observatory, Chile). Observations started
at 00:45 UT (5.12 hr after the burst), and consisted of 6x600 s exposures
covering the spectral range between 3 000 and 18 000 Angstroms.
In the acquisition image the afterglow is detected with R(Vega) = 21.0 mag,
as compared to stars of the USNOB-1.0 catalogue.
On a preliminary reduction we detect a weak continuum with absorption
features of FeII, MgII and MgI at a common redshift of z = 1.5169, which
we suggest as the redshift of the GRB.
We acknowledge the excellent support provided by Paranal staff, and in
particular Andrea Mehner, Tayyaba Zafar, and Marcelo Lopez.
GCN Circular 17524
Subject
GRB 150301B: Swift-BAT refined analysis
Date
2015-03-02T05:24:04Z (10 years ago)
From
Amy Lien at GSFC <amy.y.lien@nasa.gov>
T. N. Ukwatta (LANL), 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),
T. Sakamoto (AGU), M. Stamatikos (OSU), J. Tueller (GSFC),
(i.e. the Swift-BAT team):
Using the data set from T-60 to T+243 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 150301B (trigger #633180)
(Lien, et al., GCN Circ. 17515). The BAT ground-calculated position is
RA, Dec = 89.159, -57.969 deg which is
RA(J2000) = 05h 56m 38.3s
Dec(J2000) = -57d 58' 07.8"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 62%.
The mask-weighted light curve shows a single-peaked structure that starts at ~ T0,
peaks at ~ T+3 s, and ends at ~ T+16 s. T90 (15-350 keV) is 12.44 +- 1.49 sec
(estimated error including systematics).
The time-averaged spectrum from T-0.34 to T+15.62 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.46 +- 0.07. The fluence in the 15-150 keV band is 1.8 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+3.65 sec in the 15-150 keV band
is 3.0 +- 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/633180/BA/
GCN Circular 17525
Subject
GRB 150301B: Fermi GBM detection
Date
2015-03-02T05:26:50Z (10 years ago)
From
Eric Burns at U of Alabama <eb0016@uah.edu>
E. Burns (UAH) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:
"At 19:38:04.51 UT on 01 March 2015, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 150301B (trigger 446931487/150301818)
which was also detected by the Swift/BAT (Lien et al. 2015, GCN 17515).
The GBM on-ground location is consistent with the Swift position.
The angle from the Fermi LAT boresight is 39 degrees.
The GBM light curve consists of one main peak
with a duration (T90) of about 13 s (50-300 keV).
The time-averaged spectrum from T0-2.560 s to T0+13.824 s is
best fit by a power law function with an exponential
high-energy cutoff. The power law index is -1.2 +/- 0.1 and
the cutoff energy, parameterized as Epeak, is 256 +/- 32 keV.
A Band function fits the spectrum equally well with
Epeak= 180 +/- 38 keV, alpha = -1.1 +/- 0.1 and beta = -2.0 +/- 0.2.
The event fluence (10-1000 keV) in this time interval is
(4.4 +/- 0.2)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+2.560 s in the 10-1000 keV band
is 4.5 +/- 0.2 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."
GCN Circular 17530
Subject
GRB 150301B: LCOGT-Sutherland observations
Date
2015-03-02T09:00:17Z (10 years ago)
From
Cristiano Guidorzi at Ferrara U,Italy <guidorzi@fe.infn.it>
C. Guidorzi (U. Ferrara), J. Japelj, A. Gomboc (U. Ljubljana),
C.G. Mundell (U. Bath), on behalf of a large collaboration report:
One of the Las Cumbres Observatory 1-m telescopes in Sutherland
(South Africa) began observing Swift and Fermi GRB 150301B
(Lien et al. GCN 17515; Burns et al. GCN 17525) on March 01
at 20:07:30 UT, i.e. ~29.4 minutes after the BAT trigger
with the r', i', and g' filters.
We detect the optical afterglow (Lien et al. GCN 17515;
Buckley et al. GCN 7518; Kann et al. GCN 17522; de Ugarte
Postigo et al. GCN 17523) with the following magnitudes:
Mid time from Total Exp Filter Magnitude
trigger (min) (s)
-------------------------------------------------
37.7 360 r' 18.85 +- 0.25
42.3 360 i' 18.5 +- 0.3
-------------------------------------------------
Values have been calibrated against nearby USNOB-1 stars
(R2 and I). Compared with earlier (Buckley et el.)
and later (Kann et al.) observations, our values
suggest an overall power-law decay index ~1.
GCN Circular 17531
Subject
GRB 150301B: Swift/UVOT Observations
Date
2015-03-02T14:28:45Z (10 years ago)
From
Margaret Chester at PSU <chester@swift.psu.edu>
M. M. Chester (PSU) 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 150301B
86 s after the BAT trigger (Lien et al., GCN Circ. 17515). A fading
source consistent with the XRT position (Evans et al. GCN Circ. 17520)
and the optical transient reported by Buckley et al. (GCN Circ. 17518)
is detected in the initial UVOT exposures.
The preliminary UVOT position is:
RA (J2000) = 05:56:39.89 = 89.16622 (deg.)
Dec (J2000) = -57:58:10.4 = -57.96955 (deg.)
with an estimated uncertainty of 0.42 arc sec. (radius, 90% confidence).
Preliminary detections and 3-sigma upper limits for the White finding
chart and subsequent exposures 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_FC 86 236 147 16.2 +/- 0.1
white 3986 4121 133 >20.2
v 5833 6033 197 >19.7
b 3782 3982 197 >19.6
u 298 543 241 17.1 +/- 0.1
w1 6243 10068 579 >19.9
m2 6038 6237 197 >19.8
w2 5628 16054 963 >21.6
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.08 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 17533
Subject
GRB 150301B: Swift-XRT refined Analysis
Date
2015-03-02T19:50:04Z (10 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
A. Maselli (INAF-IASFPA), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows
(PSU), J.A. Kennea (PSU), A. Amaral-Rogers (U. Leicester), J.P. Osborne
(U. Leicester), K.L. Page (U. Leicester), A. Melandri (INAF-OAB), P.
D'Avanzo (INAF-OAB) and A.Y. Lien report on behalf of the Swift-XRT
team:
We have analysed 5.7 ks of XRT data for GRB 150301B (Lien et al. GCN
Circ. 17515), from 67 s to 69.5 ks after the BAT trigger. The data
comprise 67 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 enhanced XRT position for this burst was given by Evans et
al. (GCN Circ. 17520).
The light curve can be modelled with a power-law decay with a decay
index of alpha=1.11 (+0.05, -0.04).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.81 (+0.18, -0.10). The
best-fitting absorption column is consistent with the Galactic value
of 6.2 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 3.7 x 10^-11 (4.2 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Galactic foreground: 6.2 x 10^20 cm^-2
Intrinsic column: 6 (+/-14) x 10^20 cm^-2 at z=1.5169
Photon index: 1.81 (+0.18, -0.10)
If the light curve continues to decay with a power-law decay index of
1.11, the count rate at T+24 hours will be 3.3 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.2 x
10^-13 (1.4 x 10^-13) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00633180.
This circular is an official product of the Swift-XRT team.