GRB 150323A
GCN Circular 17611
Subject
GRB 150323A: Swift detection of a burst
Date
2015-03-23T03:01:27Z (10 years ago)
From
David Palmer at LANL <palmer@lanl.gov>
A. Amaral-Rogers (U Leicester), S. D. Barthelmy (GSFC),
F. E. Marshall (NASA/GSFC), C. J. Mountford (U Leicester),
D. M. Palmer (LANL), B. Sbarufatti (INAF-OAB/PSU) and
M. H. Siegel (PSU) report on behalf of the Swift Team:
At 02:49:14 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 150323A (trigger=635887). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 128.191, +45.434 which is
RA(J2000) = 08h 32m 46s
Dec(J2000) = +45d 26' 03"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a small peak at the
time of the trigger, followed by a much larger peak at T+130 s,
for a total duration of at least 170 sec. The peak count rate
was ~5600 counts/sec (15-350 keV), at ~130 sec after the trigger.
The XRT began observing the field at 02:51:41.2 UT, 146.6 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source located at RA, Dec 128.17951,
45.46355 which is equivalent to:
RA(J2000) = 08h 32m 43.08s
Dec(J2000) = +45d 27' 48.8"
with an uncertainty of 3.8 arcseconds (radius, 90% containment). This
location is 110 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 3.05
x 10^20 cm^-2 (Willingale et al. 2013).
The initial flux in the 0.1 s image was 3.25e-08 erg cm^-2 s^-1 (0.2-10
keV).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 156 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
0.03.
Burst Advocate for this burst is A. Amaral-Rogers (aar14 AT le.ac.uk).
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 17612
Subject
GRB 150323A: P60 Optical Afterglow Candidate
Date
2015-03-23T03:51:38Z (10 years ago)
From
S. Bradley Cenko at NASA/GSFC <brad.cenko@nasa.gov>
S. B. Cenko (NASA/GSFC) and D. A. Perley (Caltech) report on behalf of a larger collaboration:
We observed the location of the Swift GRB150323A (Amaral-Rogers et al., GCN 17611) with the robotic Palomar 60 inch telescope. Observations began at 2:57 UT (~ 8 minutes after the Swift trigger) and were obtained in the Sloan r, i, and z filters. In a stacked r-band image with a mid-point of 3:07 UT, we detect a source at the edge of the XRT error circle, with coordinates:
RA: 08:32:42.83 Dec: +45:27:53.5 (J2000.0)
At this time, we measure an r-band magnitude of ~ 20.6 (photometric calibration performed with respect to nearby point sources from SDSS). Given the lack of a quiescent counterpart in SDSS at this location, we consider this likely to be the afterglow of GRB150323A.
Observations are ongoing.
GCN Circular 17613
Subject
GRB 150323A: RATIR Optical Afterglow Observations
Date
2015-03-23T04:09:49Z (10 years ago)
Edited On
2024-11-07T19:56:10Z (7 months ago)
From
Nat Butler at Az State U <natbutler@asu.edu>
Edited By
Vidushi Sharma at NASA GSFC/UMBC <vidushi.sharma@nasa.gov> on behalf of Leo P. Singer at NASA/GSFC <leo.p.singer@nasa.gov>
Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William
H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB),
J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara
(ORAU/GSFC), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico
Ramirez-Ruiz (UCSC), José A. de Diego (UNAM), Leonid Georgiev (UNAM), Jesús
González (UNAM), Carlos Román-Zúñiga (UNAM), Neil Gehrels (GSFC), and
Harvey Moseley (GSFC) report:
We observed the field of GRB 150323A (Amaral-Rogers, et al., GCN 17611)
with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org)
on the 1.5m Harold Johnson Telescope at the Observatorio Astronómico
Nacional on Sierra San Pedro Mártir from 2015/03 23.12 to 2015/03 23.16 UTC
(9.6 to 58.8 minutes after the BAT trigger), obtaining a total of 42.6
minutes exposure in the r, i, and z bands.
For the source on the edge of the Swift-XRT error circle (Cenko et al., GCN
17612), in comparison with the SDSS DR9, we obtain the following
measurements and upper-limit (3-sigma):
r = 21.16 +/- 0.11
i = 20.39 +/- 0.05
z > 19.30
These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB. We note that this source appears
to be fading during our observation.
We thank the staff of the Observatorio Astronómico Nacional in San
Pedro Mártir.
GCN Circular 17615
Subject
GRB 150323A: Enhanced Swift-XRT position
Date
2015-03-23T06:29:57Z (10 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester)
report on behalf of the Swift-XRT team.
Using 1311 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 150323A, 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 = 128.17800, +45.46464 which is equivalent
to:
RA (J2000): 08h 32m 42.72s
Dec (J2000): +45d 27' 52.7"
with an uncertainty of 1.9 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 17616
Subject
GRB 150323A: Keck redshift
Date
2015-03-23T07:20:09Z (10 years ago)
From
Daniel Perley at Caltech <dperley@astro.caltech.edu>
D. A. Perley (Caltech) and S. B. Cenko (GSFC) report:
Using the Low Resolution Imaging Spectrometer (LRIS) on the Keck I 10m
telescope, we acquired a single 900s spectrum of the optical afterglow
(Cenko et al., GCN 17612) of GRB 150323A (Amaral-Roger et al., GCN
17611) beginning at 06:11 UT, at the end of evening twilight.
A number of absorption and emission lines are detected in the 1D
spectrum, including e.g. Fe II (2344,2374,2383,2585,2599), Mg II
(2796,2803), Mg I (2853), OII (3727), OIII (4959, 5007), and H-beta at a
common redshift of z=0.593.
We acknowledge S. Kulkarni for the observing time.
GCN Circular 17617
Subject
GRB150323A: Swift-UVOT detection of the afterglow
Date
2015-03-23T11:40:56Z (10 years ago)
From
Paul Kuin at MSSL <npkuin@gmail.com>
N. P. M. Kuin (UCL-MSSL) and Amaral-Rogers (U Leicester)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 150323A
156 s after the BAT trigger (Amaral-Rogers et al., GCN Circ. 17611).
A weak optical afterglow consistent with the XRT position (Goad et al.,
GCN Circ. 17615) or the P60 position (GCN Circ. 17612) is be present
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 156 306 147 20.53+/-0.30
u_FC 314 564 246 >20.0
white 4066 5702 1635 20.96+/-0.33
v 5912 6112 197 18.93+/-0.29
u 314 5291 442 >20.7
u 4991 5191 197 19.86+/-0.35
w1 4887 5086 197 >20.2
m2 4682 4881 197 >20.9
w2 4272 4472 197 >20.4
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.03 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 17618
Subject
GRB 150323A: Swift-XRT refined Analysis
Date
2015-03-23T15:01:04Z (10 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), B.
Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), J.A. Kennea (PSU), J.P.
Osborne (U. Leicester), K.L. Page (U. Leicester) and A. Amaral-Rogers
report on behalf of the Swift-XRT team:
We have analysed 6.5 ks of XRT data for GRB 150323A (Amaral-Rogers et
al. GCN Circ. 17611), from 136 s to 29.5 ks after the BAT trigger. The
data comprise 169 s 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 Goad
et al. (GCN Circ. 17615).
The late-time light curve (from T0+4.1 ks) can be modelled with a
power-law decay with a decay index of alpha=0.72 (+0.19, -0.16).
A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.26 (+0.06, -0.05). The
best-fitting absorption column is 6.2 (+/-0.5) x 10^21 cm^-2, at a
redshift of 0.593, in addition to the Galactic value of 3.0 x 10^20
cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index
of 2.03 (+0.20, -0.19) and a best-fitting absorption column of 4.6
(+1.8, -1.6) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10
keV flux conversion factor deduced from this spectrum is 3.4 x 10^-11
(4.7 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Galactic foreground: 3.0 x 10^20 cm^-2
Intrinsic column: 4.6 (+1.8, -1.6) x 10^21 cm^-2 at z=0.593
Photon index: 2.03 (+0.20, -0.19)
If the light curve continues to decay with a power-law decay index of
0.72, the count rate at T+24 hours will be 0.012 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.3 x
10^-13 (5.9 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/00635887.
This circular is an official product of the Swift-XRT team.
GCN Circular 17626
Subject
GRB 150323A: KAIT Optical Observations
Date
2015-03-23T21:09:12Z (10 years ago)
From
Weikang Zheng at UC Berkeley <weikang@berkeley.edu>
WeiKang Zheng and Alexei V. Filippenko (UC Berkeley) report on
behalf of the KAIT GRB team:
The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at
Lick Observatory, responded to Swift GRB 150323A (Amaral-Rogers
et al., GCN 17611) starting at 03:23:43 UT, ~34 minutes after
the burst. Observations were performed with an automatic sequence
in the clear (roughly R), V, and I filters, and the exposure time was
20 s per image. The afterglow reported by Cenko & Perley (GCN 17612)
was not detected in any single image, but was marginally detected
in the co-add image of 20 clear band images. We estimated the
brightness is R~20.3 +/- 0.3 at a mean time of 71.2 minutes after
the burst.
GCN Circular 17628
Subject
GRB 150323A, Swift-BAT refined analysis
Date
2015-03-24T01:11:42Z (10 years ago)
From
Amy Lien at GSFC <amy.y.lien@nasa.gov>
C. B. Markwardt (GSFC), A. Amaral-Rogers (U Leicester), 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),
D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU),
J. Tueller (GSFC), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
Using the data set from T-235 to T+967 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 150323A (trigger #635887)
(Amaral-Rogers, et al., GCN Circ. 17611). The BAT ground-calculated position is
RA, Dec = 128.173, 45.442 deg which is
RA(J2000) = 08h 32m 41.52s
Dec(J2000) = +45d 26' 29.76"
with an uncertainty of 2.07 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 32%.
The mask-weighted light curve shows a multi-peaked structure with two main
pulses. The first weaker pulse starts at ~ T0, peaks at ~ T+7 s, and ends at
~ T+25 s. The second brighter pulse starts at ~ T+125 s , peaks at ~ T+135 s,
and ends at ~ T+160 s. T90 (15-350 keV) is 149.6 +- 8.9 sec (estimated error
including systematics).
The time-averaged spectrum from T+2.6 to T+195.4 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.85 +- 0.07. The fluence in the 15-150 keV band is 6.1 +- 0.2 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+135.64 sec in the 15-150 keV band
is 5.4 +- 0.3 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/635887/BA/
GCN Circular 17640
Subject
Konus-Wind observation of GRB 150323A
Date
2015-03-25T14:47:56Z (10 years ago)
From
Anastasia Tsvetkova at Ioffe Institute <tsvetkova@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 GRB 150323A (Swift-BAT trigger #635887:
Amaral-Rogers et al., GCN 17611; Markwardt et al., GCN 17628)
triggered Konus-Wind at T0=10282.369 s UT (02:51:22.369).
The burst light curve shows a weak precursor at ~T0-135 s,
which triggered BAT, followed by the main episode which
started at ~T0-3 s and has a duration of ~38 s.
The emission is seen up to ~5 MeV.
As observed by Konus-Wind, the burst
had a fluence of 1.1(-0.1,+0.1)x10^-5 erg/cm2,
and a 64-ms peak energy flux, measured from T0+0.152 s,
of 1.2(-0.6,+0.6)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
The time-integrated spectrum of the burst
(measured from T0 to T0+24.832 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 = -1.22(-0.28,+0.32),
and Ep = 95(-13,+16) keV (chi2 = 70/98 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index:
beta < -2.80 (chi2 = 70/97 dof).
The spectrum near the peak count rate
(measured from T0 to T0+8.448 s)
is best fit in the 20 keV - 3 MeV range
by the power law with exponential cutoff model
with alpha = -1.21(-0.26,+0.30),
and Ep = 121(-18,+25) keV (chi2 = 71/68 dof).
Fitting by a GRB (Band) model yields almost the same alpha and Ep,
and an upper limit on the high energy photon index:
beta < -2.43 (chi2 = 71/67 dof).
Assuming the redshift z=0.593 (Perley and Cenko, GCN 17616)
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 1.0(-0.1,+0.1)x10^52 erg,
the peak luminosity L_iso is 1.7(-0.8,+0.8)x10^51 erg/s,
and the rest-frame peak energy of the time-integrated spectrum,
Ep,i, is 151(-21,+25) keV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB150323_T10282/
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.
GCN Circular 17642
Subject
GRB 150323A; Konkoly optical observations
Date
2015-03-25T20:36:46Z (10 years ago)
Edited On
2025-04-09T18:43:57Z (2 months ago)
From
Janos Kelemen at Konkoly Obs/Hungary <kelemen@konkoly.hu>
Edited By
Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov> on behalf of Tyler Barna at University of Minnesota <tylerpbarna@gmail.com>
J. Kelemen (kelemen at konkoly.hu) on behalf of the GRB OT observing program
at the Konkoly Observatory.
Starting on the evening 23/03/2015 18:30 UT we observed the field GRB 150323A
(A. Amaral-Rogers et al. GCN 17611, and M.R. Goad et al. GCN 17615).
We can confirm the presence of the supposed afterglow reported by
S. B. Cenko (NASA/GSFC) and D. A. Perley (Caltech) (GCN 17612) at the position
RA: 08:32:42.69 DEC: 45:27:53.6
Our position and the P60 position are the same within 1 pixel.
On the coadded images (total exposure time = 2400 sec) we measured an R -band
magnitude of m(R) = 20.3 +/- 0.14 with respect to nearby USNO-B1.0 stars.
time from GRB. exp filter Mag.
------------------------------------------------
56136 s. 2400 s R 20.3 +/-0.14
------------------------------------------------
GCN Circular 17647
Subject
GRB 150323A: AAO optical observations
Date
2015-03-26T18:41:23Z (10 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
E. Mazaeva (IKI), R. Inasaridze (AAO), Sh. Makandarashvili (AAO), A.
Volnova (IKI), I. Molotov (KIAM), A. Pozanenko (IKI) report on behalf of
larger GRB follow-up collaboration:
We observed the field of the Swift GRB 150323A (Amaral-Rogers et al., GCN
17611) with AS-32 (0.7m) telescope of Abastumani Observatory starting on
Mar. 23 (UT) 22:47:06. Within the enhanced XRT position (Goad et al., GCN
17615) we do not detect any object. An upper limit is following
Date UT start t-T0 Filter Exp. UL(3 sigma)
(mid, days) (s)
2015-03-23 22:47:06 0.85076 None 15*180 21.2
The photometry is based on nearby USNO-B1.0 stars.