TITLE: GCN CIRCULAR
NUMBER: 36759
SUBJECT: GRB 240624B: GRBAlpha detection
DATE: 24/06/25 15:53:18 GMT
FROM: Marianna Dafčíková at Masaryk University <500025(a)mail.muni.cz>
M. Dafcikova, J. Ripa, M. Kolar (Masaryk U.), A. Pal (Konkoly Observatory), N. Werner (Masaryk U.), M. Ohno, H. Takahashi (Hiroshima U.), L. Meszaros, B. Csak (Konkoly Observatory), N. Husarikova, F. Munz , M. Topinka, M. Duriskova, L. Szakszonova, J.-P. Breuer, F. Hroch (Masaryk U.), T. Urbanec, M. Kasal, A. Povalac (Brno U. of Technology), J. Hudec, J. Kapus, M. Frajt (Spacemanic s.r.o), R. Laszlo, M. Koleda (Needronix s.r.o), M. Smelko, P. Hanak, P. Lipovsky (Technical U. of Kosice), G. Galgoczi (Wigner Research Center/Eotvos U.), Y. Uchida, H. Poon, H. Matake (Hiroshima U.), N. Uchida (ISAS/JAXA), T. Bozoki (Eotvos U.), G. Dalya (Eotvos U.), T. Enoto (Kyoto U.), Zs. Frei (Eotvos U.), G. Friss (Eotvos U.), Y. Fukazawa, K. Hirose (Hiroshima U.), S. Hisadomi (Nagoya U.), Y. Ichinohe (Rikkyo U.), K. Kapas (Eotvos U.), L. L. Kiss (Konkoly Observatory), T. Mizuno (Hiroshima U.), K. Nakazawa (Nagoya U.), H. Odaka (Univ of Tokyo), J. Takatsy (Eotvos U.), K. Torigoe (Hiroshima U.), N. Kogiso, M. Yoneyama (Osaka Metropolitan U.), M. Moritaki (U. Tokyo), T. Kano (U. Michigan) -- the GRBAlpha collaboration.
The long-duration GRB 240624B (Fermi/GBM detection: GCN 36749) was observed by the GRBAlpha 1U CubeSat (Pal et al. 2023, A&A, 677, 40; https://ui.adsabs.harvard.edu/abs/2023A%26A...677A..40P/abstract).
The detection was confirmed at the peak time 2024-06-24 19:19:46.0 UTC. The T90 duration measured by GRBAlpha is 8.5 s and the overall significance during T90 reaches 7.8 sigma.
The light curve obtained by GRBAlpha is available here: https://grbalpha.konkoly.hu/static/share/GRB240624B_GCN.pdf
All GRBAlpha detections are listed at: https://monoceros.physics.muni.cz/hea/GRBAlpha/
GRBAlpha, launched on 2021 March 22, is a demonstration mission for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). The detector of GRBAlpha consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from ~50 keV to ~1000 keV. To increase the duty cycle and the downlink rate, the upgrade of the on-board data acquisition software stack is in progress. The ground segment is also supported by the radio amateur community and it takes advantage of the SatNOGS network for increased data downlink volume.
View this GCN Circular online at https://gcn.nasa.gov/circulars/36759.
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TITLE: GCN CIRCULAR
NUMBER: 36757
SUBJECT: EP240625a: EP-WXT detection of a fast X-ray transient
DATE: 24/06/25 11:04:29 GMT
FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn>
X. Pan, Z. Z. Lv (NAOC, CAS), Y. C. Fu (BNU), Y. Liu, Z. X. Ling, C. Zhang, C. C. Jin, W. Chen, H. Q. Cheng, C. Z. Cui, D. W. Fan, H. B. Hu, J. W. Hu, M. H. Huang, D. Y. Li, H. Y. Liu, M. J. Liu, T. Y. Lian, X. Mao, H. W. Pan, H. Sun, W. X. Wang, Y. L. Wang, Q. Y. Wu, X. P. Xu, Y. F. Xu, H. N. Yang, W. Yuan, M. Zhang, W. D. Zhang, W. J. Zhang, Z. Zhang, D. H. Zhao (NAOC, CAS), Y. Chen, S. M. Jia, S. N. Zhang (IHEP, CAS), E. Kuulkers, A. Santovincenzo (ESA), P. O'Brien (Univ. of Leicester), K. Nandra, A. Rau (MPE), B. Cordier (CEA) on behalf of the Einstein Probe team
We report on the detection of a fast X-ray transient, designated EP240625a, by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission. The transient triggered the WXT on-board processing unit at 2024-06-25T01:48:23 (UTC). The position of the source is R.A. = 310.760 deg, DEC = -15.966 deg (J2000) with an uncertainty of 2 arcmin in radius (90% C.L. statistical and systematic). The transient event lasts for approximately 300 seconds and has a peak unabsorbed flux of ~1.3 x 10^-9 erg/s/cm^2 in the 0.5-4 keV band. The average 0.5-4 keV spectrum can be fitted by an absorbed power law with a photon index of 1.8(+/-0.3) (with the column density fixed at the Galactic value of 3.85 x 10^20 cm^-2). The derived average unabsorbed 0.5-4 keV flux is 2.9(+0.7/-0.5) x 10^-10 erg/s/cm^2. The uncertainties are at the 1 sigma level for the above parameters. No previously known X-ray sources at a similar flux level are found within the 2 arcmin region around the source position.
Following the WXT detection, we performed a follow-up observation with the Follow-up X-ray Telescope (FXT) on board the EP. Further follow-up observations are encouraged to identify the nature of this X-ray transient.
The above observation was made with the WXT instrument during the commissioning phase of EP. Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics). EP is a mission of the Chinese Academy of Sciences in collaboration with ESA, MPE and CNES.
View this GCN Circular online at https://gcn.nasa.gov/circulars/36757.
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TITLE: GCN CIRCULAR
NUMBER: 36756
SUBJECT: GRB240624A: Fermi GBM Observation
DATE: 24/06/25 07:59:09 GMT
FROM: Cuán de Barra at UCD <cuan.debarra(a)ucdconnect.ie>
C. de Barra (UCD) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team:
"At 06:01:11.37 UT on 24 June 2024, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 240624A (trigger 740901676/240624251).
which was also detected by Swift BAT (N. J. Klingler et al. 2024, GCN 36743).
The Fermi GBM on-ground location is consistent with the Swift BAT position.
The angle from the Fermi LAT boresight is 83 degrees.
The GBM light curve consists of a single emission episode with a duration (T90)
of about 2 s (50-300 keV). The time-averaged spectrum
from T0-3.1 to T0+2.0 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -0.45 +/- 0.39 and the cutoff energy,
parameterized as Epeak, is 90 +/- 13 keV.
The event fluence (10-1000 keV) in this time interval is
(7.0 +/- 0.8)E-07 erg/cm^2. The 64-ms peak photon flux measured
starting from T0+0.38 s in the 10-1000 keV band is 6 +/- 1 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html
For Fermi GBM data and info, please visit the official Fermi GBM Support Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"
View this GCN Circular online at https://gcn.nasa.gov/circulars/36756.
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TITLE: GCN CIRCULAR
NUMBER: 36755
SUBJECT: LIGO/Virgo/KAGRA S240622h: Upper limits from Swift/BAT-GUANO
DATE: 24/06/25 02:49:36 GMT
FROM: Samuele Ronchini at PSU <sjs8171(a)psu.edu>
Samuele Ronchini (PSU), Gayathri Raman (PSU), Aaron Tohuvavohu (U Toronto), Jamie A. Kennea (PSU), James DeLaunay (PSU), Tyler Parsotan (NASA GSFC) report:
Swift/BAT was observing >99% of the GW localization probability ([Bilby.multiorder.fits](https://gracedb.ligo.org/api/superevents/S240622h/fi…) at merger time. A fraction <1% 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](https://iopscience.iop.org/article/10.3847/1538-4357/aba94f)).
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](https://iopscience.iop.org/article/10.3847/1538-4357/ac9d38)), 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 |20.8 | 13.3 | 11.7 | 14.9
|1.024 |10.6 | 6.78 | 5.98 | 7.61
|4.096 |5.74 | 3.66 | 3.23 | 4.11
|16.384 |3.60 | 2.30 | 2.02 | 2.57
The upper limits as function of sky position are plotted here, alongside the GW localization:
[https://doi.org/10.5281/zenodo.12524835]()
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/36755.
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TITLE: GCN CIRCULAR
NUMBER: 36754
SUBJECT: LIGO/Virgo/KAGRA S240621dy: Upper limits from Swift/BAT-GUANO
DATE: 24/06/25 02:49:31 GMT
FROM: Samuele Ronchini at PSU <sjs8171(a)psu.edu>
Samuele Ronchini (PSU), James DeLaunay (PSU), Aaron Tohuvavohu (U Toronto), Jamie A. Kennea (PSU), Gayathri Raman (PSU), Tyler Parsotan (NASA GSFC) report:
Swift/BAT was observing >99% of the GW localization probability ([bayestar.multiorder.fits](https://gracedb.ligo.org/api/superevents/S240621d…) at merger time. A fraction <1% 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](https://iopscience.iop.org/article/10.3847/1538-4357/aba94f)).
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](https://iopscience.iop.org/article/10.3847/1538-4357/ac9d38)), 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 |30.8 | 20.8 | 18.4 | 23.3
|1.024 |15.7 | 10.6 | 9.38 | 11.9
|4.096 |8.48 | 5.73 | 5.06 | 6.41
|16.384 |5.20 | 3.51 | 3.10 | 3.93
The upper limits as function of sky position are plotted here, alongside the GW localization:
[https://doi.org/10.5281/zenodo.12519328]()
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/36754.
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TITLE: GCN CIRCULAR
NUMBER: 36753
SUBJECT: LIGO/Virgo/KAGRA S240618ah: Upper limits from Swift/BAT-GUANO
DATE: 24/06/25 02:49:25 GMT
FROM: Samuele Ronchini at PSU <sjs8171(a)psu.edu>
Samuele Ronchini (PSU), Tyler Parsotan (NASA GSFC), Aaron Tohuvavohu (U Toronto), Jamie A. Kennea (PSU), James DeLaunay (PSU), Gayathri Raman (PSU) report:
Swift/BAT was observing 53% of the GW localization probability ([bayestar.multiorder.fits](https://gracedb.ligo.org/api/superevents/S240618a…) at merger time. A fraction 14% 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](https://iopscience.iop.org/article/10.3847/1538-4357/aba94f)).
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](https://iopscience.iop.org/article/10.3847/1538-4357/ac9d38)), 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 |6.68 | 5.16 | 4.83 | 5.49
|1.024 |3.42 | 2.64 | 2.47 | 2.81
|4.096 |1.85 | 1.42 | 1.33 | 1.52
|16.384 |1.16 | 0.90 | 0.84 | 0.95
The upper limits as function of sky position are plotted here, alongside the GW localization:
[https://doi.org/10.5281/zenodo.12519163]()
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/36753.
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TITLE: GCN CIRCULAR
NUMBER: 36752
SUBJECT: Swift GRB 240624A: Global MASTER-Net observations report
DATE: 24/06/25 02:27:06 GMT
FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru>
V. Lipunov, V.Kornilov, E. Gorbovskoy, K. Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, V.Senik, D. Vlasenko,
G.Antipov, D.Zimnukhov, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D. Cheryasov, Ya.Kechin, Yu.Tselik, A. Sosnovskij
(Lomonosov Moscow State University, SAI, Physics Department),
R. Podesta, C.Lopez, F. Podesta, C.Francile
(Observatorio Astronomico Felix Aguilar OAFA),
R. Rebolo, M. Serra
(The Instituto de Astrofisica de Canarias),
D. Buckley
(South African Astronomical Observatory),
O.A. Gress, N.M. Budnev, O.Ershova
(Irkutsk State University, API),
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez,
A.R.Corella, L.H.Rodriguez
(INAOE, Guillermo Haro Astrophysics Observatory),
A. Tlatov, D. Dormidontov
(Kislovodsk Solar Station of the Pulkovo Observatory),
V. Yurkov, A. Gabovich
(Blagoveschensk Educational State University)
MASTER-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) was pointed to the Swift GRB 240624A ( N. J. Klingler et al., GCN 36743) errorbox 39782 sec after notice time and 39803 sec after trigger time at 2024-06-24 17:04:33 UT, with upper limit up to 15.4 mag. Observations started at twilight. The observations began at zenith distance = 84 deg. The sun altitude is -16.8 deg.
The galactic latitude b = -3 deg., longitude l = 219 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=2505317
We obtain a following upper limits.
Tmid-T0 | Site |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________
39893 | MASTER-SAAO | C | 180 | 15.4 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
View this GCN Circular online at https://gcn.nasa.gov/circulars/36752.
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TITLE: GCN CIRCULAR
NUMBER: 36750
SUBJECT: Fermi GRB 240624A: Global MASTER-Net observations report
DATE: 24/06/25 02:27:05 GMT
FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru>
V. Lipunov, V.Kornilov, E. Gorbovskoy, K. Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, V.Senik, D. Vlasenko,
G.Antipov, D.Zimnukhov, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D. Cheryasov, Ya.Kechin, Yu.Tselik, A. Sosnovskij
(Lomonosov Moscow State University, SAI, Physics Department),
R. Podesta, C.Lopez, F. Podesta, C.Francile
(Observatorio Astronomico Felix Aguilar OAFA),
R. Rebolo, M. Serra
(The Instituto de Astrofisica de Canarias),
D. Buckley
(South African Astronomical Observatory),
O.A. Gress, N.M. Budnev, O.Ershova
(Irkutsk State University, API),
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez,
A.R.Corella, L.H.Rodriguez
(INAOE, Guillermo Haro Astrophysics Observatory),
A. Tlatov, D. Dormidontov
(Kislovodsk Solar Station of the Pulkovo Observatory),
V. Yurkov, A. Gabovich
(Blagoveschensk Educational State University)
MASTER-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB 240624A ( Fermi GBM team, GCN 36745) errorbox 39761 sec after notice time and 39801 sec after trigger time at 2024-06-24 17:04:33 UT, with upper limit up to 15.4 mag. Observations started at twilight. The observations began at zenith distance = 84 deg. The sun altitude is -16.8 deg.
The galactic latitude b = 5 deg., longitude l = 228 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=2505441
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
39892 | 2024-06-24 17:04:33 | MASTER-SAAO | (06h 49m 40.87s , -06d 32m 06.9s) | C | 180 | 15.4 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
View this GCN Circular online at https://gcn.nasa.gov/circulars/36750.
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