TITLE: GCN CIRCULAR
NUMBER: 41067
SUBJECT: EP250702a: gamma-ray upper limits from joint observations by the LST-1 and MAGIC telescopes
DATE: 25/07/11 17:01:56 GMT
FROM: David Paneque at Max Planck Institute for Physics <dpaneque(a)mppmu.mpg.de>
D. Paneque (MPP Munich), M. Teshima (MPP Munich), Arnau Aguasca-Cabot (UB, ICCUB, and IEEC-UB), Alessio Berti (MPP Munich), Sweta Menon (UNIROMA2 & INAF), Edna Ruiz-Velasco (LAPP Annecy), Monica Seglar-Arroyo (IFAE Barcelona) and …
[View More]Andrea Simongini (UNIROMA2 & INAF), on behalf of the CTAO-LST and MAGIC Collaborations report:
We observed the field of EP250702a / GRBs 250702B,D,E (GCN 40883, 40886, 40890, 40891, 40906). A total of 2.94 hours of observations were conducted with the MAGIC telescopes, beginning at 2025-07-04 01:25:53 UTC. The final 1.79 hours of this period were carried out jointly with LST-1.
A preliminary offline analysis of the LST-1 and MAGIC dataset shows no excess of gamma rays above 200 GeV in the field of EP250702a (GCN 40906). These results have been obtained using the LST analysis software, lst-chain (LST Collaboration, 2023 ApJ 956 80, v0.10.7), and the MAGIC analysis software MARS (Zanin et al. 2013, v 3.2.1). Observations were affected by reduced atmospheric transparency. A more in-depth analysis of this data set is ongoing.
Subsequent observations are planned after the moonbreak, subject to the nature of upcoming detections.
LST-1 is a prototype of the Large-Sized Telescope (LST) for the Cherenkov Telescope Array Observatory, and is located on the Canary island of La Palma, Spain. The telescope design is optimized for observation of gamma rays in the range from 20 GeV to 3 TeV.
MAGIC is a system of two 17m-diameter Imaging Atmospheric Cherenkov Telescopes located on the Canary island of La Palma, Spain, and designed to perform gamma-ray astronomy in the energy range from 50 GeV to greater than 50 TeV.
View this GCN Circular online at https://gcn.nasa.gov/circulars/41067.
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TITLE: GCN CIRCULAR
NUMBER: 41066
SUBJECT: GRB 250704A: GRANDMA observations
DATE: 25/07/11 16:12:40 GMT
FROM: Sarah Antier at OCA <sarah.antier(a)oca.eu>
A. Manasanun, K. Noysena (NARIT), R. Hellot (KNC), S. Antier (OCA/IJCLAB), D. Akl (AUS), N. Kochiashivili (AbAO), T. Du Laz (Caltech), A. Klotz (IRAP), C. Limonta (OCA), M. Masek (FZU), M. Lamoureux (UCLouvain) on behalf of GRANDMA:
We observed the field of SVOM GRB 250704A (Cao et al., GCN Circ. 40934) with TAROT, TRT and …
[View More]Kilonova catcher.
All our measurements are made public and can be downloaded from: https://skyportal-icare.ijclab.in2p3.fr/public/sources/GCN-250704_034220/ve…
All the data have been reduced by a single data processing pipeline, STDPipe (Karpov et al., 2025). Images obtained with the Sloan filters were calibrated using the PanSTARRS DR1 catalog. Images obtained with the Johnson-Cousin filters were calibrated using the Gaia DR3 Synphot catalog.
We use the SkyPortal application (skyportal.io) to monitor our observational campaign (Coughlin et al. 2023).
Our observations are consistent with previously reported measurements (see the Skyportal page), such as Schneider et al., GCN Circ. 40953; Cao et al., GCN Circ 40964; and Siegel et al., GCN 40981.
GRANDMA is a worldwide telescope network (grandma.ijclab.in2p3.fr) devoted to the observation of transients in the context of multi-messenger astrophysics (Antier et al. 2020 MNRAS 497, 5518). Kilonova-Catcher (KNC) is the citizen science program of GRANDMA (http://kilonovacatcher.in2p3.fr/).
Skyportal/ICARE is supported by ACME.
View this GCN Circular online at https://gcn.nasa.gov/circulars/41066.
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TITLE: GCN CIRCULAR
NUMBER: 41065
SUBJECT: GRB 250711A: BALROG localization (Fermi Trigger 773937617 / GRB 250711611)
DATE: 25/07/11 15:08:21 GMT
FROM: Jochen Greiner at MPE <jcgrog(a)mpe.mpg.de>
T. Preis (University of Innsbruck) & J. Greiner (MPE Garching) report:
The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger
773937617 at 14:40:12 on 11 July 2025 were automatically fitted for spectrum
and sky location with BALROG (Burgess et al. 2018, MNRAS …
[View More]476, 1427;
Berlato et al. 2019, ApJ 873, 60).
The best-fit position is:
RA(2000.0) = 267.8 deg
Decl.(2000.0) = 35.9 deg
The 1 sigma statistical error radius is 2.1 deg.
We estimate an additional systematic error of 1 deg.
Further details are available at:
https://grb.mpe.mpg.de/grb/GRB250711611/
The Healpix map can be downloaded from:
https://grb.mpe.mpg.de/grb/GRB250711611/healpix
The location parameters are available as JSON at:
https://grb.mpe.mpg.de/grb/GRB250711611/json
View this GCN Circular online at https://gcn.nasa.gov/circulars/41065.
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TITLE: GCN CIRCULAR
NUMBER: 41063
SUBJECT: GRB 250704A: SVOM/ECLAIRs refined analysis
DATE: 25/07/11 12:20:56 GMT
FROM: SVOM_group <svomgroup(a)bao.ac.cn>
Authors: N. Dagoneau (CEA), U. Jacob (LUPM), J.X Cao (GXU), Y.H Cheng (SWIFAR, YNU), J.-L. Atteia, M. Brunet, O. Godet (IRAP), F. Cangemi, A. Coleiro (APC)
Using the event-by-event data downloaded through the X-band ground station, we report further analysis of ECLAIRs observations of GRB 250704A (SVOM burst-id sb25070404).
…
[View More]The burst that triggered ECLAIRs onboard (GCN 40934) consists of a single pulse with a duration of T90 = 9.0 +0.6/-0.5 s in the 4-120 keV energy band.
The time-averaged spectrum of the burst from T0 - 1.50 s to T0 + 7.48 s (T0 = 2025-07-04T03:42:22) in the energy range 8-120 keV is best fit by a power-law model with a photon index of -1.3 +/- 0.2. With this model, the total 4-120 keV fluence, assuming the T90 measured, is 1.23 +/- 0.21 x 10^-6 erg/cm^2.
All the quoted errors are at the 68% confidence level.
The Space-based multi-band astronomical Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA), French Space Agency (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic Universe. ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC.
The SVOM/ECLAIRs point of contact for this burst is: Nicolas Dagoneau (nicolas.dagoneau at cea.fr)
View this GCN Circular online at https://gcn.nasa.gov/circulars/41063.
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TITLE: GCN CIRCULAR
NUMBER: 41062
SUBJECT: LIGO/Virgo/KAGRA S250711q: Identification of a GW compact binary merger candidate
DATE: 25/07/11 04:36:24 GMT
FROM: Jyotirmaya Mohanta at University of Tsukuba <s2430161(a)u.tsukuba.ac.jp>
The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report:
We identified the compact binary merger candidate S250711q during real-time processing of data from LIGO Hanford Observatory (H1), LIGO Livingston …
[View More]Observatory (L1), and Virgo Observatory (V1) at 2025-07-11 03:27:25.108 UTC (GPS time: 1436239663.108). The candidate was found by the cWB [1], cWB BBH [2], GstLAL [3], and MBTA [4] analysis pipelines.
S250711q is an event of interest because its false alarm rate, as estimated by the online analysis, is 1.6e-09 Hz, or about one in 20 years. The event's properties can be found at this URL:
https://gracedb.ligo.org/superevents/S250711q
The classification of the GW signal, in order of descending probability, is BBH (>99%), Terrestrial (<1%), NSBH (<1%), or BNS (<1%).
Assuming the candidate is astrophysical in origin, the probability that at least one of the compact objects is consistent with a neutron star mass (HasNS) is <1%. [5] Using the masses and spins inferred from the signal, the probability of matter outside the final compact object (HasRemnant) is <1%. [5] Both HasNS and HasRemnant consider the support of several neutron star equations of state for maximum neutron star mass. The probability that either of the binary components lies between 3 and 5 solar masses (HasMassGap) is <1%.
The source chirp mass falls with highest probability in the bin (22.0, 44.0) solar masses, assuming the candidate is astrophysical in origin.
Two sky maps are available at this time and can be retrieved from the GraceDB event page:
* bayestar.multiorder.fits,0, an initial localization generated by BAYESTAR [6], distributed via GCN and SCiMMA notices about 31 seconds after the candidate event time.
* bayestar.multiorder.fits,1, an initial localization generated by BAYESTAR [6], distributed via GCN and SCiMMA notices about 5 minutes after the candidate event time.
The preferred sky map at this time is bayestar.multiorder.fits,1. For the bayestar.multiorder.fits,1 sky map, the 90% credible region is 2964 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 9738 +/- 2925 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] Klimenko et al. PRD 93, 042004 (2016) doi:10.1103/PhysRevD.93.042004
[2] T. Mishra et al. PRD 105, 083018 (2022) doi:10.1103/PhysRevD.105.083018
[3] Tsukada et al. PRD 108, 043004 (2023) doi:10.1103/PhysRevD.108.043004 and Ewing et al. PRD 109, 042008 (2024) doi:10.1103/PhysRevD.109.042008
[4] Alléné et al. CQG 42, 105009 (2025) doi:10.1088/1361-6382/add234
[5] Chatterjee et al. ApJ 896, 54 (2020) doi:10.3847/1538-4357/ab8dbe
[6] Singer & Price PRD 93, 024013 (2016) doi:10.1103/PhysRevD.93.024013
View this GCN Circular online at https://gcn.nasa.gov/circulars/41062.
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TITLE: GCN CIRCULAR
NUMBER: 41060
SUBJECT: GRB 250704B / EP250704a: 1.3 GHz MeerKAT Detection
DATE: 25/07/10 20:58:22 GMT
FROM: Genevieve Schroeder at Cornell University <genevieveschroeder(a)u.northwestern.edu>
G. Schroeder (Cornell), L. Rhodes (TSI/McGill), W. Fong (Northwestern), T. Laskar (Utah), E. Berger (Harvard) report:
We observed the location of the short-duration GRB 250704B/EP 250704A (Wang et al., GCN 40940; Li et al., GCNs 40941, 40956, Frederiks et al., GCN 40972;…
[View More] Wang et al., GCN 40978; Shimizu et al., GCN 41025) with the MeerKAT radio telescope under program MKT-24032 (PI Schroeder) at a central frequency of 1.3 GHz for a total of 2 hours with a mid time of 2025 July 10 at 00:07 UT (5.7 days post burst).
In preliminary analysis, we detect the radio afterglow (Schroeder et al., GCN 41038; Ricci et al., GCN 41046), and measure a flux density of ~70 microJy. Further observations are planned.
We thank the staff at the South African Radio Astronomy Observatory for scheduling these observations.
View this GCN Circular online at https://gcn.nasa.gov/circulars/41060.
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TITLE: GCN CIRCULAR
NUMBER: 41059
SUBJECT: GRB 250702B,D,E / EP250702a: ALMA detection
DATE: 25/07/10 18:59:43 GMT
FROM: Kate D. Alexander at University of Arizona <katedenhamalexander(a)gmail.com>
Kate D. Alexander (U of Arizona), James Miller-Jones (Curtin U), Adelle Goodwin, (Curtin U), Noah Franz (U of Arizona), Raffaella Margutti (UC Berkeley) Ryan Chornock (UC Berkeley), Dheeraj Pasham (Eureka Scientific/George Washington), Edo Berger (Harvard), Yvette Cendes (U of Oregon),…
[View More] and Collin Christy (U of Arizona) report on behalf of a larger collaboration:
We observed the location of the unusual transient GRB 250702B,D,E / EP250702a (GCNs 40906, 40883, 40885, 40886, 40890, 40891) with the Atacama Large Millimeter/submillimeter Array (ALMA) at multiple frequencies (program 2023.1.01731.T, PI: Miller-Jones). On 2025 July 9 02:09:03 UT, 6.97 days after the first detection with the Einstein Probe (GCN 40906) and 6.51 days after the first Fermi trigger (GCN 40883), we clearly detected the source at a mean frequency of 97.5 GHz with a preliminary flux density of ~2 mJy. Further ALMA observations are planned.
We thank the ALMA staff for quickly scheduling these observations and for providing the quick-look reduction.
View this GCN Circular online at https://gcn.nasa.gov/circulars/41059.
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