TITLE: GCN CIRCULAR
NUMBER: 36612
SUBJECT: Swift Trigger 1232755: likely consistent with noise and not astrophysical
DATE: 24/06/04 13:18:33 GMT
FROM: Amy <yarleen(a)gmail.com>
A. P. Beardmore (U Leicester), A. A. Breeveld (UCL-MSSL), A. Y. Lien (U
Tampa), D. M. Palmer (LANL) and T. M. Parsotan (GSFC) report on behalf of
the Neil Gehrels Swift Observatory Team:
Using the full data set from recent downlinks, we report further ground
data analysis for Swift trigger 1232755 (initially called GRB240603B;
Beardmore et al. GCN Circ. 36604).
The BAT analysis uses data from T-239 s to T+963 s. There are several very
noisy detectors during this time interval. Further ground analysis after
removing the contributions from these noisy detectors shows an image
significance of 7.5 sigma and a small bump in the BAT mask-weighted light
curve from ~T0 to ~T+0.5 s. However, since there are many active noisy
detectors around this time, we also see higher chances of getting
detections above 7 sigma. Thus, the signal is likely to be consistent with
the larger noise fluctuation.
Swift performed a follow-up observation of the trigger, with XRT collecting
1.1 ks of Photon Counting (PC) mode data between T0+3.3 ks and T0+4.6 ks.
No X-ray sources were detected within 296 arcsec of the initially reported
BAT position. The 3-sigma upper limit in the field ranges from ~0.005 to
~0.007 ct s^-1, corresponding to a 0.3-10 keV observed flux of 2.1e-13 to
2.7e-13 erg cm^-2 s^-1 (assuming a typical GRB spectrum).
Additionally, no optical afterglow consistent with the BAT position 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 initial exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white 4758 4958 197 >20.2
b 4553 4753 197 >19.6
u 4347 4547 197 >19.2
v 3733 3932 197 >18.7
uvw1 4143 4342 197 >19.2
uvw2 3528 5102 332 >19.6
uvm2 3939 4137 197 >19.2
The increased detector noise visible in BAT and the absence of any X-ray
and optical afterglow detection, suggest this trigger did not have an
astrophysical origin and is consistent with noise fluctuations.
View this GCN Circular online at https://gcn.nasa.gov/circulars/36612.
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TITLE: GCN CIRCULAR
NUMBER: 36610
SUBJECT: LIGO/Virgo/KAGRA S240601co: Upper limits from Swift/BAT-GUANO
DATE: 24/06/04 01:59:52 GMT
FROM: Samuele Ronchini at PSU <sjs8171(a)psu.edu>
Samuele Ronchini (PSU), Jamie A. Kennea (PSU), James DeLaunay (PSU), Gayathri Raman (PSU), Tyler Parsotan (NASA GSFC), Aaron Tohuvavohu (U Toronto) report:
Swift/BAT was observing 54% of the GW localization probability (bayestar.multiorder.fits) at merger time. A fraction 5% of the GW localization posterior is contained inside the BAT coded FoV.
The LVK notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1).
Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from [-50,+150] seconds around the time of the burst. All the requested event mode data was delivered to the ground.
Using the NITRATES analysis (DeLaunay + Tohuvavohu 2022, ApJ, 941, 169), we searched for emission on 8 timescales from 0.128s to 16.384s in the interval [-20,+20] seconds around the merger time. We find no evidence for a signal, and derive the following upper limits.
We quote the 5-sigma flux upper limits in the 15-350 keV band, weighted over the GW localization, for four spectral templates (soft, normal, and hard GRB-like templates described in [arXiv:1612.02395], and spectral shape from GRB170817A [arXiv:1710.05446]) and for four time bins.
In units of 10^-7 erg/s/cm^2:
time_bin (s) soft normal hard GRB170817
------------------------------------
0.256 22.6 15.2 13.4 17.1
1.024 15.4 10.3 9.14 11.6
4.096 13.0 8.72 7.70 9.77
16.384 12.3 8.26 7.29 9.26
The upper limits as function of sky position are plotted here, alongside the GW localization:
https://doi.org/10.5281/zenodo.11458821
The solid and dashed lines indicate the 90% and 50% GW contour levels, respectively. The corresponding fits file is also included.
GUANO is a fully autonomous, extremely low latency, spacecraft
commanding pipeline designed for targeted recovery of BAT event mode
data around the times of compelling astrophysical events to enable
more sensitive GRB searches.
A live reporting of Swift/BAT event data recovered by GUANO can be
found at: https://www.swift.psu.edu/guano/
View this GCN Circular online at https://gcn.nasa.gov/circulars/36610.
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TITLE: GCN CIRCULAR
NUMBER: 36609
SUBJECT: LIGO/Virgo/KAGRA S240530a: Upper limits from Swift/BAT-GUANO
DATE: 24/06/04 01:59:27 GMT
FROM: Samuele Ronchini at PSU <sjs8171(a)psu.edu>
Samuele Ronchini (PSU), Jamie A. Kennea (PSU), James DeLaunay (PSU), Gayathri Raman (PSU), Tyler Parsotan (NASA GSFC), Aaron Tohuvavohu (U Toronto) report:
Swift/BAT was observing 96% of the GW localization probability (Bilby.offline0.multiorder.fits) at merger time. A fraction 0.0% of the GW localization posterior is contained inside the BAT coded FoV.
The LVK notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1).
Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from [-50,+150] seconds around the time of the burst. All the requested event mode data was delivered to the ground.
Using the NITRATES analysis (DeLaunay + Tohuvavohu 2022, ApJ, 941, 169), we searched for emission on 8 timescales from 0.128s to 16.384s in the interval [-20,+20] seconds around the merger time. We find no evidence for a signal, and derive the following upper limits.
We quote the 5-sigma flux upper limits in the 15-350 keV band, weighted over the GW localization, for four spectral templates (soft, normal, and hard GRB-like templates described in [arXiv:1612.02395], and spectral shape from GRB170817A [arXiv:1710.05446]) and for four time bins.
In units of 10^-7 erg/s/cm^2:
time_bin (s) soft normal hard GRB170817
------------------------------------
0.256 5.54 4.12 4.04 4.22
1.024 2.85 2.12 2.08 2.17
4.096 1.56 1.16 1.14 1.19
16.384 0.96 0.72 0.70 0.73
The upper limits as function of sky position are plotted here, alongside the GW localization:
https://doi.org/10.5281/zenodo.11458717
The solid and dashed lines indicate the 90% and 50% GW contour levels, respectively. The corresponding fits file is also included.
GUANO is a fully autonomous, extremely low latency, spacecraft
commanding pipeline designed for targeted recovery of BAT event mode
data around the times of compelling astrophysical events to enable
more sensitive GRB searches.
A live reporting of Swift/BAT event data recovered by GUANO can be
found at: https://www.swift.psu.edu/guano/
View this GCN Circular online at https://gcn.nasa.gov/circulars/36609.
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TITLE: GCN CIRCULAR
NUMBER: 36607
SUBJECT: GRB 240603C: BALROG localization (Fermi Trigger 739102156 / GRB 240603423)
DATE: 24/06/03 10:59:23 GMT
FROM: Jochen Greiner at MPE <jcgrog(a)mpe.mpg.de>
T. Preis, B. Biltzinger, J. Burgess & J. Greiner (all MPE Garching) report:
The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger
739102156 at 10:09:11 on 03 June 2024 were automatically fitted for spectrum
and sky location with BALROG (Burgess et al. 2018, MNRAS 476, 1427;
Berlato et al. 2019, ApJ 873, 60).
The best-fit position is:
RA(2000.0) = 275.5 deg
Decl.(2000.0) = -35.3 deg
The 1 sigma statistical error radius is 2.5 deg.
We estimate an additional systematic error of 1 deg.
Further details are available at:
https://grb.mpe.mpg.de/grb/GRB240603423/
The Healpix map can be downloaded from:
https://grb.mpe.mpg.de/grb/GRB240603423/healpix
The location parameters are available as JSON at:
https://grb.mpe.mpg.de/grb/GRB240603423/json
View this GCN Circular online at https://gcn.nasa.gov/circulars/36607.
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TITLE: GCN CIRCULAR
NUMBER: 36605
SUBJECT: Swift Trigger 1232465: consistent with noise
DATE: 24/06/03 07:33:30 GMT
FROM: K.L. Page at U Leicester <klp5(a)leicester.ac.uk>
A. Y. Lien (U. Tampa) and K. L. Page (U. Leicester)
report on behalf of the Swift team:
Using the full data set from recent downlinks, we report further
ground data analysis for Swift trigger 1232465 (Gropp et al.
GCN Circ. 36593).
The BAT analysis uses data from T-61 to T+302 sec. The BAT image
significance has now decreased to 5.3 sigma (15-350 keV).
Also, the mask-weighted light curve does not show
anything significantly above the noise fluctuation.
Analysing the 1.2 ks of XRT data collected between 107 s and 6 ks
after the trigger, no source is detected to a 3-sigma upper limit
range of 0.007 - 0.011 count s^-1 (0.3-10 keV) within the BAT error
circle.
We thus conclude that this trigger was consistent with noise fluctuations.
View this GCN Circular online at https://gcn.nasa.gov/circulars/36605.
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TITLE: GCN CIRCULAR
NUMBER: 36604
SUBJECT: GRB 240603B: Swift detection of a possible burst
DATE: 24/06/03 07:29:50 GMT
FROM: K.L. Page at U Leicester <klp5(a)leicester.ac.uk>
A. P. Beardmore (U Leicester), A. Y. Lien (U Tampa) and
K. L. Page (U Leicester) report on behalf of the Neil Gehrels Swift
Observatory Team:
At 06:57:43 UT, the Swift Burst Alert Telescope (BAT) triggered
and located on a possible GRB 240603B (trigger=1232755).
Swift did not slew immediately to the location.
The BAT on-board calculated location is
RA, Dec 36.054, -50.944 which is
RA(J2000) = 02h 24m 13s
Dec(J2000) = -50d 56' 38"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve did not show any
significant structures, despite the light curve fluctuated greatly
from ~4000 ct/s to ~10000 ct/s. Also, the source was detected with
marginal significance (7.0 sigma) in the image, but the source is
no longer detected in the scaled map from ground analysis.
Therefore, the trigger may be due to a noisy detector. However,
further ground data and XRT/UVOT observation is required to confirm
the nature of the trigger.
Due to an observing constraint, Swift will not slew until T0+54.8
minutes. There will be no XRT or UVOT data until this time.
Burst Advocate for this burst is A. P. Beardmore (apb AT star.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/)
View this GCN Circular online at https://gcn.nasa.gov/circulars/36604.
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TITLE: GCN CIRCULAR
NUMBER: 36603
SUBJECT: GRB 240529A: MASTER prompt OT detection
DATE: 24/06/03 05:40:18 GMT
FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru>
V.Lipunov (MSU), D.Buckley (SAAO),
K.Zhirkov, G.Antipov, E.Gorbovskoy, A.Kuznetsov, D.Vlasenko, P.Balanutsa,
N.Tiurina, Ya.Kechin, Yu.Tselik, D.Zimnukhov, V.Senik, A.Yudin, V.Topolev,
A.Chasovnikov,D.Cheryasov(Lomonosov MSU,SAI,PhysicsDepartment),
O.Gress, N.Budnev(ISU),
A.Sosnovskij (Crimean Astrophysical Observatory, RAS),
C.Francile. F. Podesta, R.Podesta (Observatorio Astronomico Felix AguilarOAFA),
R. Rebolo, M. Serra(The Instituto de Astrofisica de Canarias),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity)
MASTER Global robotic net (http://observ.pereplet.ru Lipunov etal.,2010,Advances in Astronomy,2010,30L)
started observation (Lipunov et al. GCN 36555) of Swift GRB240529A (Eyles-Ferris et al. GCN36556, Ttrigger= 02:58:31UT)
in MASTER-SAAO at 3 degrees altitude at 2024-05-29 02:59:20 by wide-field MASTER-II camera and
at 2024-05-29 02:59:16 (44s after GRB time) by very wide field MASTER-VWF camera.
The optical transient MASTER OT J222126.06+513344.6 clearly detected since
03:00:20 with m_OT~14.5 at first maximum and with possible second maximum at light curve
during prompt emission of this GRB (Swift-BAT lightcurve Markwardt,Barthelmy et al. GCN36566)
The reduction of first 40 images from MASTER-VWFC since 2024-05-29 02:59:16 with OT substraction will be continued.
Observations started at zenith distance = 87 deg. The sun altitude was -31.0deg.
The galactic latitude b = -5 deg., longitude l = 101 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=2474976
View this GCN Circular online at https://gcn.nasa.gov/circulars/36603.
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