TITLE: GCN CIRCULAR
NUMBER: 36620
SUBJECT: LIGO/Virgo/KAGRA S240601co: Updated Sky localization
DATE: 24/06/05 15:09:19 GMT
FROM: Aditya Vijaykumar <aditya.vijaykumar(a)ligo.org>
The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report:
We have conducted further analysis of the LIGO Hanford Observatory (H1), LIGO Livingston Observatory (L1), and Virgo Observatory (V1) data around the time of the compact binary merger (CBC) candidate S240601co (GCN Circular 36594). Parameter estimation has been performed using Bilby [1] and a new sky map, Bilby.offline0.multiorder.fits,0, distributed via GCN Notice, is available for retrieval from the GraceDB event page:
https://gracedb.ligo.org/superevents/S240601co
For the Bilby.offline0.multiorder.fits,0 sky map, the 90% credible region is 1110 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 1421 +/- 390 Mpc (a posteriori mean +/- standard deviation).
For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/.
[1] Ashton et al. ApJS 241, 27 (2019) doi:10.3847/1538-4365/ab06fc and Morisaki et al. (2023) arXiv:2307.13380
View this GCN Circular online at https://gcn.nasa.gov/circulars/36620.
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TITLE: GCN CIRCULAR
NUMBER: 36618
SUBJECT: IPN triangulation of GRB 240603A
DATE: 24/06/05 12:19:02 GMT
FROM: Dmitry Svinkin at Ioffe Institute <svinkin(a)mail.ioffe.ru>
A.S. Kozyrev, D.V. Golovin, M.L. Litvak, I.G. Mitrofanov, and A.B. Sanin
on behalf of the HEND/Mars Odyssey team,
D. Svinkin, D. Frederiks, A. Ridnaia, A. Lysenko,
and T. Cline on behalf of the Konus-Wind team,
A. Goldstein, M. S. Briggs, C. Wilson-Hodge,
and E. Burns on behalf of the Fermi GBM team,
E. Bozzo and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,
and
W. Boynton, C. Fellows, K. Harshman, H. Enos, R. Starr,
and A.S. Gardner on on behalf of the GRS-Odyssey GRB team,
report:
The short-duration GRB 240603A
(GECAM-B detection: Wang et al., GCN 36602;
Fermi-GBM detection: The Fermi GBM team, GCN 36608)
was detected by Fermi (GBM trigger 739074458), Konus-Wind
INTEGRAL (SPI-ACS), GECAM-B, and Mars-Odyssey (HEND)
at about 8853 s UT (02:27:33).
We have triangulated it to a preliminary, 3 sigma error box
whose coordinates are:
---------------------------------------------
RA(2000), deg Dec(2000), deg
---------------------------------------------
Center:
328.634 (21h 54m 32s) -24.049 (-24d 02' 58")
Corners:
329.538 (21h 58m 09s) -25.739 (-25d 44' 21")
329.570 (21h 58m 17s) -25.919 (-25d 55' 10")
327.632 (21h 50m 32s) -22.008 (-22d 00' 28")
327.575 (21h 50m 18s) -21.746 (-21d 44' 44")
---------------------------------------------
The error box area is 821 sq. arcmin, and its maximum
dimension is 4.56 deg (the minimum one is 3.2 arcmin).
The Sun distance was 110 deg.
The IPN localization is consistent with, but reduces the area of,
the Fermi-GBM final localization.
This localization may be improved.
A triangulation map and HEALPix FITS file are posted at
http://www.ioffe.ru/LEA/GRBs/GRB240603_T08857/IPN
The HEALPix triangulation map is the multi-order HEALPix in units of probability density.
The Konus-Wind time history and spectrum will be given
in a forthcoming GCN Circular.
View this GCN Circular online at https://gcn.nasa.gov/circulars/36618.
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TITLE: GCN CIRCULAR
NUMBER: 36614
SUBJECT: GRB 240604A: GECAM detection of a long burst
DATE: 24/06/05 03:03:06 GMT
FROM: yqzhang_cl(a)163.com
Yan-Qiu Zhang, Shao-Lin Xiong report on behalf of the GECAM team:
GECAM-B was triggered in-flight by a long burst, GRB 240604A, at 2024-06-04T22:28:29.050 UTC (T0), which was also detected by INTEGRAL/SPI-ACS (trigger #10730).
According to the realtime alert data of GECAM-B, the GECAM-B light curve shows a long pulse with a duration of ~50 sec (15-1020 keV). The time-averaged spectrum from T0-1 to T0+16 s could be adequately fit by a power law with high energy exponential cutoff function with a fluence of about 7.04E-6 erg/cm^2 in 20-1000 keV.
The GECAM light curve could be found here:
https://twikinew.ihep.ac.cn/pubgecam/Sandbox/GRB/gecam-b_lc_grd_all_combine…
The GECAM-B in-flight location (J2000) is:
Ra: 286.8 deg
Dec: 79.5 deg
Err: 3.7 deg (1-sigma, statistical only)
The GECAM preliminary location could be found here:
https://twikinew.ihep.ac.cn/pubgecam/Sandbox/GRB/gecam-b_skymap_flt_1712393…
We note that these results are very preliminary. Refined analysis will be reported later.
Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor(GECAM) mission originally consists of two microsatellites (GECAM-A and GECAM-B) launched in Dec. 2020. As the third member of GECAM constellation, GECAM-C was launched onboard SATech-01 experimental satellite in July 2022. GECAM mission is funded by the Chinese Academy of Sciences (CAS).
View this GCN Circular online at https://gcn.nasa.gov/circulars/36614.
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TITLE: GCN CIRCULAR
NUMBER: 36613
SUBJECT: GRB 240529A: SAO RAS optical observations
DATE: 24/06/04 15:21:45 GMT
FROM: Moskvitin Alexander at SAO RAS <mosk(a)sao.ru>
A. S. Moskvitin, O. A. Maslennikova, O. I. Spiridonova (SAO RAS),
report on behalf of the GRB follow-up team.
We observed the field of the GRB 240529A (Eyles-Ferris et al.
GCN 36556; Osborne et al. GCN 36557; Joshi et al. GCN 36560;
Dichiara et al. GCN 36564; Markwardt et al. GCN 36566; Tan et al.
GCN 36578; Kozyrev et al. GCN 36583; Svinkin et al. GCN 36584)
with the SAO RAS 1m telescope Zeiss-1000 equipped with CCD-photometer.
We obtained 15 x 200 sec frames in the Rc band on June 3, 23:17:01 --
June 4, 00:16:47 UT (t_mid - T0 = 5.8669 days).
The OT (Kumar et al. GCN 36559; Fu et al. GCN 36561; Shilling et al.
GCN 36562; Perez-Garcia et al. GCN 36563; Dutton et al. GCN 36568;
Mo et al. GCN 36569; Odeh et al. GCNs 36573, 36592;
de Ugarte Postigo et al. GCN 36574; Adami et al. GCN 36575;
Mohan et al. GCN 36576; Vinko et al. GCN 36577; Lim et al. GCN 36579;
Moskvitin et al. GCNs 36582, 36597; 36601; Pankov et al. GCN 36585;
Ror et al., 36589; Hu et al. GCN 36599; Lipunov et al., GCN 36603)
is clearly detected in the stacked frame with the brightness of
R = 20.96 +/- 0.09.
The magnitudes were calibrated using R2 magnitudes of nearby USNO-B1.0
stars.
View this GCN Circular online at https://gcn.nasa.gov/circulars/36613.
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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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