GRB 210514A
GCN Circular 30008
Subject
GRB 210514A: Swift detection of a burst
Date
2021-05-14T19:02:01Z (4 years ago)
From
Kim Page at U.of Leicester <klp5@leicester.ac.uk>
E. Ambrosi (INAF-IASFPA), A. D'Ai (INAF-IASFPA), N. J. Klingler (PSU),
F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester) and
B. Sbarufatti (PSU) report on behalf of the Neil Gehrels Swift
Observatory Team:
The Swift Burst Alert Telescope (BAT) has triggered on a new event and Swift has
slewed to the location of this trigger. The trigger time is believed to be no
earlier than 17:08 UT. Given the loss of real-time antennae for half the sky, we
are unable to confirm the nature, location, or exact time of this trigger until
the full data have been downloaded, in approximately 3 hours (by around 22:00 UT).
Limited XRT and UVOT data have been received. No counterpart is detected; however,
given the location of the image centre, we infer that the BAT position must have
been around RA,Dec = 2.9670, -21.8750 degrees (J2000.0), with an uncertainty of 12���.
Burst Advocate for this burst is E. Ambrosi (elena.ambrosi AT inaf.it).
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 30009
Subject
GRB 210514A: update on the BAT trigger time and burst duration
Date
2021-05-15T00:05:01Z (4 years ago)
From
Amy Lien at GSFC <amy.y.lien@nasa.gov>
A. Y. Lien (GSFC/UMBC) and E. Ambrosi (INAF-IASFPA)
report on behalf of the Neil Gehrels Swift Observatory Team:
We received further data from the recent telemetry downlink.
The trigger time for GRB 210514A (Swift trigger #1048372;
Ambrosi et al., GCN Circ. 30008) is
2021-05-14T18:23:47 UTC.
Based on currently available data from T-61 to T+242 sec,
the BAT ground-calculated position is
RA, Dec = 2.945, -21.898 deg which is
RA(J2000) = 00h 11m 46.8s
Dec(J2000) = -21d 53' 52.1"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 79%.
The BAT mask-weighted light curve shows a multi-peaked structure
with a total duration of ~80 s.
Using 1.3 ks of the XRT data in Window Timing mode,
the XRT location is RA,Dec = 2.95362, -21.88562 deg.
GCN Circular 30011
Subject
GRB 210514A: Enhanced Swift-XRT position
Date
2021-05-15T08:19:53Z (4 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester)
report on behalf of the Swift-XRT team.
Using 3253 s of XRT Photon Counting mode data and 8 UVOT
images for GRB 210514A, 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 = 2.96184, -21.89454 which is equivalent
to:
RA (J2000): 00h 11m 50.84s
Dec (J2000): -21d 53' 40.3"
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 30012
Subject
GRB 210514A: Swift-XRT refined Analysis
Date
2021-05-15T08:29:00Z (4 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), K.L. Page (U.
Leicester), M.G. Bernardini (INAF-OAB), M. Capalbi (INAF-IASFPA), A.
Tohuvavohu (U. Toronto), B. Sbarufatti (PSU), D.N. Burrows (PSU) and E.
Ambrosi report on behalf of the Swift-XRT team:
We have analysed 6.7 ks of XRT data for GRB 210514A (Ambrosi et al. GCN
Circ. 30008), from 60 s to 23.8 ks after the BAT trigger. The data
comprise 1.4 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 Osborne et
al. (GCN Circ. 30011). We cannot determine at the present time whether
the source is fading.
A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.06 (+/-0.04). The
best-fitting absorption column is 4.79 (+/-0.22) x 10^21 cm^-2, in
excess of the Galactic value of 2.0 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.95 (+0.12, -0.11)
and a best-fitting absorption column of 4.7 (+0.7, -0.6) 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 (6.5 x 10^-11) erg cm^-2
count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 4.7 (+0.7, -0.6) x 10^21 cm^-2
Galactic foreground: 2.0 x 10^20 cm^-2
Excess significance: 12.2 sigma
Photon index: 1.95 (+0.12, -0.11)
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01048372.
This circular is an official product of the Swift-XRT team.
GCN Circular 30013
Subject
GRB 210514A: Swift XRT light curve is fading
Date
2021-05-15T08:45:43Z (4 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:
GCN Circular 30012 stated that we cannot determine whether the XRT afterglow of GRB 210514A is fading. This was incorrect. The light curve shows the so-called ���canonical��� X-ray afterglow behaviour, and can be modelled thus:
Alpha_1 : 3.44 (+0.14, -0.15)
Tbreak_1: 141 (+6, -5) sec
Alpha_2 : 1.22 (+0.18, -0.17)
Tbreak_2: 276.7 (+16.8, -15.6) sec
Alpha_3 : -0.14 (+0.06, -0.05)
Tbreak_3: (1.02 [+0.04, -0.03]) �� 10^3 sec
Alpha_4 : 1.236 (+0.024, -0.022)
We apologise for the confusion; this was the result of the automated XRT software not operating completely correctly in the circumstances that some of the prompt TDRSS messages are missing. We are working urgently to understand and rectify these issues.
The online analysis is available at the usual website (https://www.swift.ac.uk/xrt_products/01048372).
This circular is an official product of the Swift-XRT team.
GCN Circular 30018
Subject
GRB 210514A: Swift-BAT refined analysis
Date
2021-05-15T17:59:15Z (4 years ago)
From
Hans Krimm at NSF/NASA-GSFC <hkrimm@nsf.gov>
C. B. Markwardt (GSFC), E. Ambrosi (INAF-IASFPA) S. D. Barthelmy (GSFC),
H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC),
D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU),
T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
Using the data set from T-240 to T+962 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 210514A (trigger #1048372)
(Lien, et al., GCN Circ. 30009). The BAT ground-calculated position is
RA, Dec = 2.947, -21.898 deg which is
RA(J2000) = 00h 11m 47.2s
Dec(J2000) = -21d 53' 54.0"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 79%.
The mask-weighted light curve showed a complex structure of five main peaks
with sub-peaks. Emission started around T-1 sec and continued to T+75 sec.
T90 (15-350 keV) is 70.21 +- 0.74 sec (estimated error including systematics).
The time-averaged spectrum from T-1.08 to T+75.13 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.65 +- 0.04. The fluence in the 15-150 keV band is 7.4 +- 0.2 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T-0.52 sec in the 15-150 keV band
is 8.7 +- 0.4 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/1048372/BA/
GCN Circular 30025
Subject
GRB 210514A: Swift/UVOT Upper Limits
Date
2021-05-16T15:01:02Z (4 years ago)
From
Alexander Belles at PSU/Swift <aub1461@psu.edu>
A. Belles (PSU) and E. Ambrosi (INAF-IASFPA)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 210514A
80 s after the BAT trigger (Ambrosi et al., GCN Circ. 30008).
No optical afterglow consistent with the XRT position
(Osborne et al., GCN Circ. 30011) 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 first
finding chart (FC) exposure and subsequent exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white_FC 80 229 147 >20.85
u_FC 293 543 245 >20.12
white 573 1366 225 >21.00
v 622 1415 97 >18.87
b 548 1342 77 >19.73
u 696 5458 210 >19.99
w1 672 5299 278 >19.59
m2 646 1440 97 >18.41
w2 598 1391 97 >18.52
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.022 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 30035
Subject
GRB 210514A: CALET Gamma-Ray Burst Monitor detection
Date
2021-05-17T10:10:30Z (4 years ago)
From
Valentin Pal'shin at AGU <val@phys.aoyama.ac.jp>
T. Sakamoto, A. Yoshida, V. Pal'shin, S. Sugita (AGU),
Y. Kawakubo (LSU), K. Yamaoka (Nagoya U), S. Nakahira (RIKEN),
Y. Asaoka (ICRR), S. Torii, Y. Akaike, K. Kobayashi (Waseda U),
Y. Shimizu, 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 bright GRB 210514A (Swift detection: Ambrosi et al., GCN Circ.
30008, Lien and Ambrosi, GCN Circ. 30009, Markwardt et al., GCN Circ.
30018; https://gcn.gsfc.nasa.gov/other/210514A.gcn3) triggered the CALET
Gamma-ray Burst Monitor (CGBM) at 18:23:42.591 UTC on 14 May 2021
(http://cgbm.calet.jp/cgbm_trigger/flight/1305051705/index.html).
The burst signal was seen by all CGBM detectors.
The burst light curve shows several partially overlapped pulses which
start at T+3.3 sec, peak at T+4.9 sec, and end at T+53.8 sec.
The T90 and T50 durations measured by the SGM data are 46.0 +- 2.5 sec
and 25.9 +- 3.3 sec (40-1000 keV), respectively.
The ground processed light curve is available at
http://cgbm.calet.jp/cgbm_trigger/ground/1305051705/
The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at the Waseda University.
GCN Circular 30048
Subject
Konus-Wind detection of GRB 210514A
Date
2021-05-18T18:03:52Z (4 years ago)
From
Anna Ridnaia at Ioffe Institute <ridnaia@mail.ioffe.ru>
A. Ridnaia, D. Frederiks, S. Golenetskii, A. Lysenko, D. Svinkin,
A. Tsvetkova, M. Ulanov, and T. Cline, report:
The long-duration GRB 210514A
(Swift-BAT detection: Ambrosi et al., GCN 30008;
Lien & Ambrosi, GCN 30009; Markwardt et al., GCN 30018;
CALET-CGBM detection: Sakamoto et al., GCN 30035)
triggered Konus-Wind at T0=66225.021 s UT (18:23:45.021).
The burst light curve shows a multipeaked structure
started at ~T0-0.3 s with a total duration of ~74.2 s.
The emission is seen up to ~2 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB210514_T66225/
As observed by Konus-Wind, the burst
had a fluence of 1.97(-0.43,+0.56)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+1.168 s,
of 6.70(-3.12,+3.85)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+49.408 s)
is best fit in the 20 keV - 2 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.38(-0.40,+0.88),
the high energy photon index beta = -2.27(-0.42,+0.23),
the peak energy Ep = 118(-24,+40) keV
(chi2 = 66/55 dof).
The spectrum near the maximum count rate
(measured from T0 to T0+8.448 s)
is best fit in the 20 keV - 2 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.42(-0.53,+1.22),
the high energy photon index beta = -2.26(2.26,+0.39),
the peak energy Ep = 204(-82,+113) keV
(chi2 = 57/55 dof).
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.