November 2024 - vsnet-grb-info - ooruri.kusastro.kyoto-u.ac.jp

[vsnet-grb-info 36332] EP trigger ID 01709122294: 1.6m Mephisto multi-band optical observations
by GCN Circulars 27 Nov '24

27 Nov '24

TITLE: GCN CIRCULAR NUMBER: 38340 SUBJECT: EP trigger ID 01709122294: 1.6m Mephisto multi-band optical observations DATE: 24/11/27 10:04:16 GMT FROM: Brajesh Kumar at SWIFAR, YNU <brajesh(a)ynu.edu.cn> Jianhui Lian, Kaushik Chatterjee, Xinlei Chen, Jinghua Zhang, Brajesh Kumar, Guowang Du, Tao Wang, Yuan Fang, Xingzhu Zou, Yu Pan, Yuanpei Yang, Xiangkun Liu, Xiaowei Liu (SWIFAR, YNU) report on behalf of the Mephisto Team: We performed uvgr band observations of the likely EP flare event (trigger ID 01709122294; Yang et al., GCN 38289) with the 1.6m Multi-channel Photometric Survey Telescope (Mephisto) of Yunnan University located at Lijiang Observatory. The observations were initiated at 12:49:16 UTC 2024-11-21 (~18.65 hours after the trigger) and continued up to 19:46:23 UTC 2024-11-21. Multiple frames with different exposure times were acquired. Our preliminary analysis indicates the decaying nature of the flare in the u and v bands during the observations. The u and v magnitudes decayed ~0.24 and 0.11 within ~7 hours. However, no significant variations were noticed in the g and r bands. -------------------------------------------------------------------------- Mephisto (Multi-channel Photometric Survey Telescope) is a 1.6m wide-field multi-channel telescope, the first of its type in the world, capable of imaging the same field of view in three optical bands simultaneously. It provides real-time, high-quality colors of stellar objects. The on-site telescope assemblage and commissioning were carried out in September 2022. The first light in all three channels was achieved on 2023 December 21. -------------------------------------------------------------------------- View this GCN Circular online at https://gcn.nasa.gov/circulars/38340. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 36331] EP241126a: EP-FXT follow-up observation update
by GCN Circulars 27 Nov '24

27 Nov '24

TITLE: GCN CIRCULAR NUMBER: 38339 SUBJECT: EP241126a: EP-FXT follow-up observation update DATE: 24/11/27 09:51:05 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> T. C. Zheng, D. F. Hu (PMO, CAS), B.-T. Wang (YNAO, CAS), M. J. Liu, H. Q. Cheng, C. C. Jin (NAO, CAS) on behalf of the Einstein Probe team Following the detection of the fast X-ray transient EP241126a (Hu et al., GCN 38335), we performed an observation of EP241126a with the Follow-up X-ray Telescope (FXT) on board the Einstein Probe. The observation started at 2024-11-27T03:08:53 (UTC), about 7.5 hours after the EP-WXT detection, with an exposure time of 2980 seconds. An uncatalogued X-ray source is detected at R.A. = 33.7444 deg, DEC = 11.7013 deg (J2000) with an uncertainty of 10 arcsec in radius (90% C.L. statistical and systematic). The average FXT spectrum in 0.5-10 keV band can be fitted by an absorbed power law with a photon index of 2.2(+0.7/-0.7) (with a column density fixed at the Galactic one of 7.4 x 10^20 cm^-2), giving an average unabsorbed flux of 1.3(+1.1/-0.5) x 10^(-13) erg/s/cm^2 in the 0.5-10 keV band. The FXT position is ~10 arcsec away from the likely optical counterpart detected by TRT (Fu et al., GCN 38337) and LCO (Li et al. GCN 38338). We thus suggest the FXT detection being associated with EP241126a. 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). View this GCN Circular online at https://gcn.nasa.gov/circulars/38339. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 36330] EP241126a: GSP detects optical counterpart
by GCN Circulars 27 Nov '24

27 Nov '24

TITLE: GCN CIRCULAR NUMBER: 38338 SUBJECT: EP241126a: GSP detects optical counterpart DATE: 24/11/27 08:59:09 GMT FROM: Wenxiong Li <liwenxiong1992(a)gmail.com> W. X. Li, S. J. Xue (NAOC), M. Andrews, J. Farah, D. A. Howell, M. Newsome, E. Padilla Gonzalez, C. McCully, and G. Terreran (Las Cumbres Observatory), on behalf of a larger collaboration, report: Following the detection of the fast X-ray transient EP241126a by the Einstein Probe (Hu et al., GCN 38335) with the Sinistro instrument mounted on the 1-m telescope of the LCO, we initiated observations of the fast X-ray transient location starting on 2024 November 27 at 5:03 UT (~9.5 hours after the EP/WXT trigger) in the r band. These observations were conducted using the 1-meter telescope at the Las Cumbres Observatory node located at Cerro Tololo Interamerican Observatory in Chile. The optical counterpart (Fu et al., GCN 38337) was detected in the co-added images with r = 22.2+-0.2. These observations were taken as part of the Global Supernova Project. View this GCN Circular online at https://gcn.nasa.gov/circulars/38338. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 36329] EP241126a: TRT optical counterpart detection
by GCN Circulars 27 Nov '24

27 Nov '24

TITLE: GCN CIRCULAR NUMBER: 38337 SUBJECT: EP241126a: TRT optical counterpart detection DATE: 24/11/27 08:39:43 GMT FROM: Dong Xu at NAOC/CAS <dxu(a)nao.cas.cn> S.Y. Fu, S.Q. Jiang (NAOC), S. Tinyanont, R. Anutarawiramkul, P. Butpan (NARIT), Z. Fan, W.X. Li, N.C. Sun, Y.N. Wang, D. Xu (NAOC) report on behalf of a large collaboration: We observed the field of EP241126a detected by Einstein Probe (EP, Hu et al., GCN 38335), using the 0.7-m telescope of the Thai Robotic Telescope (TRT) network, located at Cerro Tololo Inter-American Observatory, Chile. Observations started at 02:29:48 UT on 2024-11-27, i.e., 6.84 hr after the EP trigger, and 10 x 300 s frames were obtained in the R-band. An uncatalogued optical source is detected in the stacked frame within the EP/FXT error circle (Hu et al., GCN 38335) and localized at coordinates R.A. (J2000) = 02:14:57.96 Dec. (J2000) = +11:42:04.76 with an uncertainty of ~ 0.8 arcsec. The source has R ~ 22.0 mag at a median time of 7.59 hr after the EP trigger, calibrated with PanSTARRS and not corrected for Galactic extinction. In the Legacy Survey there is no source at the above position, down to limiting magnitude r ~ 24.0. We thus conclude that the source is the optical counterpart of EP241126a. View this GCN Circular online at https://gcn.nasa.gov/circulars/38337. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 36328] LIGO/Virgo/KAGRA S241127aj: Identification of a GW compact binary merger candidate
by GCN Circulars 27 Nov '24

27 Nov '24

TITLE: GCN CIRCULAR NUMBER: 38336 SUBJECT: LIGO/Virgo/KAGRA S241127aj: Identification of a GW compact binary merger candidate DATE: 24/11/27 06:48:14 GMT FROM: Gaurav Waratkar at IIT Bombay <gauravwaratkar(a)iitb.ac.in> The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We identified the compact binary merger candidate S241127aj during real-time processing of data from LIGO Hanford Observatory (H1), LIGO Livingston Observatory (L1), and Virgo Observatory (V1) at 2024-11-27 06:10:08.230 UTC (GPS time: 1416723026.230). The candidate was found by the cWB [1], cWB BBH [2], GstLAL [3], MBTA [4], PyCBC Live [5], and SPIIR [6] analysis pipelines. S241127aj is an event of interest because its false alarm rate, as estimated by the online analysis, is 6.5e-39 Hz, or about one in 1e31 years. The event's properties can be found at this URL: https://gracedb.ligo.org/superevents/S241127aj The classification of the GW signal, in order of descending probability, is BBH (>99%), NSBH (<1%), BNS (<1%), or Terrestrial (<1%). There was a noise transient (glitch) in the Virgo detector near the event time which may affect the localization of the candidate. Assuming the candidate is astrophysical in origin, the probability that the lighter compact object is consistent with a neutron star mass (HasNS) is <1%. [7] Using the masses and spins inferred from the signal, the probability of matter outside the final compact object (HasRemnant) is <1%. [7] 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%. 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 [8], distributed via GCN notice about 29 seconds after the candidate event time. * bayestar.multiorder.fits,1, an initial localization generated by BAYESTAR [8], distributed via GCN notice 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 80 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 729 +/- 181 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. (2023) arXiv:2305.05625 [4] Aubin et al. CQG 38, 095004 (2021) doi:10.1088/1361-6382/abe913 [5] Dal Canton et al. ApJ 923, 254 (2021) doi:10.3847/1538-4357/ac2f9a [6] Chu et al. PRD 105, 024023 (2022) doi:10.1103/PhysRevD.105.024023 [7] Chatterjee et al. ApJ 896, 54 (2020) doi:10.3847/1538-4357/ab8dbe [8] Singer & Price PRD 93, 024013 (2016) doi:10.1103/PhysRevD.93.024013 View this GCN Circular online at https://gcn.nasa.gov/circulars/38336. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 36327] EP241126a: EP detection of a fast X-ray transient
by GCN Circulars 27 Nov '24

27 Nov '24

TITLE: GCN CIRCULAR NUMBER: 38335 SUBJECT: EP241126a: EP detection of a fast X-ray transient DATE: 24/11/27 03:48:24 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> D.F. Hu, T. C. Zheng (PMO, CAS), B.-T. Wang (YNAO, CAS), M. J. Liu, H. Q. Cheng, C. C.Jin (NAO, CAS) on behalf of the Einstein Probe team We report on the detection of a fast X-ray transient detected by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission, EP241126a (Obs.ID: 06800000262). The transient was first detected with WXT at around 2024-11-26 19:39:41 (UTC) and lasted for over 60 seconds. The WXT position of EP241126a is R.A.= 33.744 deg, DEC = 11.705 deg (J2000) with an uncertainty of 2.429 arcmin (radius, 90% C.L. statistical and systematic). It has a peak flux of ~2 x 10^(-8) erg/s/cm^2 in the 0.5-4 keV band. The average 0.5-4 keV spectrum can be fitted with an absorbed power law with a photon index of 0.9 (+0.4/-0.4) (with a column density fixed at the Galactic value of 7.4 x 10^20 cm^-2). The derived average unabsorbed 0.5-4 keV flux is 3.3 (+0.9/-0.7) x 10^(-9) erg/s/cm^2. The uncertainties are at the 90% confidence level for the above parameters. We have performed a target of opportunity (ToO) observation with the Follow-up X-ray Telescope (FXT) on board EP. The FXT onboard trigger shows an X-ray detection within the WXT error circle, at a position of R.A. = 33.7394 deg, DEC = 11.7001 deg (J2000) with an uncertainty of 20 arcsec (radius, 90% C.L. statistical and systematic). More details will be updated once the telemetry data is received. No previously known bright X-ray sources are found within the error circle around the source position. More follow-up observations are encouraged to identify its nature. 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). View this GCN Circular online at https://gcn.nasa.gov/circulars/38335. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 36326] LIGO/Virgo/KAGRA S241125n: COLIBRÍ Upper Limits on Optical Counterparts to Two of the Swift/XRT Sources
by GCN Circulars 27 Nov '24

27 Nov '24

TITLE: GCN CIRCULAR NUMBER: 38334 SUBJECT: LIGO/Virgo/KAGRA S241125n: COLIBRÍ Upper Limits on Optical Counterparts to Two of the Swift/XRT Sources DATE: 24/11/27 01:54:00 GMT FROM: Alan Watson at UNAM <alan(a)astro.unam.mx> D. Akl (AUS), S. Antier (OCA), J.-G. Ducoin (CPPM), Francesco Magnani (CPPM), Alan M. Watson (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Jean-Luc Atteia (IRAP), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Francis Fortin (IRAP), Simona Lombardo (LAM), and Margarita Pereyra (UNAM) report: We imaged the field of the Swift/BAT-GUANO candidate counterpart (DeLaunay et al., GCN Circ. 38308) of the GW compact binary merger candidate S241125n (LIGO/Virgo/KAGRA Collaborations, GCN Circ. 38305) during the commissioning of the COLIBRÍ (SVOM/F-GFT) telescope at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir in Mexico. We observed with the engineering test camera in a red filter that approximates SDSS r from 2024-11-26 02:08 to 07:50 UTC (25.1 to 30.8 hours after the event) and obtained 255 minutes of exposure on a field about 12 arcmin to a side centered on the BAT position given by DeLaunay et al. (GCN Circ. 38308). Results from a subset of these observations were reported by Watson et al. (GCN Circ. 38317). Our image includes the positions of the S241125n_X3 and S241125n_X5 XRT sources (Page et al., GCN 38324). We do not detect any clear candidates within the localization regions of these sources to a 3-sigma upper limit of r > 23.4 Our upper limits are consistent with GCN. 38314, 38325, GCN 38328, GCN 38329. We warmly thank the COLIBRÍ engineering team and the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir. We warmly thank the GRANDMA IJCLAB team and S. Karpov for the access of the STDWeb service for STDPipe. View this GCN Circular online at https://gcn.nasa.gov/circulars/38334. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 36324] LIGO/Virgo/KAGRA S241125n: SAGUARO follow-up observations with the MMT
by GCN Circulars 27 Nov '24

27 Nov '24

TITLE: GCN CIRCULAR NUMBER: 38333 SUBJECT: LIGO/Virgo/KAGRA S241125n: SAGUARO follow-up observations with the MMT DATE: 24/11/27 00:47:02 GMT FROM: Manisha Shrestha at University of Arizona <mshrestha1(a)arizona.edu> Jillian C. Rastinejad (NU), Manisha Shrestha (UA), Griffin Hosseinzadeh (UCSD), David J. Sand (UA), Charles D. Kilpatrick (NU), Wen-fai Fong (NU), Bhagya Subrayan (UA), K. Azalee Bostroem (UA), Philip N. Daly (UA), Michael J. Lundquist (Keck), Kerry Paterson (MPIA) report on behalf of the SAGUARO collaboration: We observed the field of the Swift/BAT trigger (DeLauney et al. GCN 38308) discovered within the localization region of the GW event S241125n (LIGO/Virgo/KAGRA GCN 38305) with the Binospec imager and spectrograph mounted on the MMT 6.5-meter telescope on Mount Hopkins, Arizona. We obtain 20x75 s imaging in the r-band at a mid-time of 2024-11-26 08:08:50 UT (1.30 days post-burst) and 30x60 s in the i-band at a mid-time of 2024-11-26 09:13:11 UT (1.34 days post-burst). Observations were taken at an average airmass of 1.3 and seeing of 1.2 - 1.8’’. Our observations covered 68.0 percent of the 5 arcmin BAT localization (DeLauney et al. GCN 38308) and the localization region of XRT source S241125n_X2 (Page et al. GCN 38324). Calibrated to PS1 (Flewelling et al. 2020), our imaging reached limiting magnitudes of r>25.5 mag and i>25.5 mag (3 sigma; AB system). Within the error circle of S241125n_X2, we report magnitudes for 5 sources, as shown in the table below. The bright source (S241125n_X2_O5) is in the PS1 catalog, and the rest are below the PS1 detection limit. Therefore we cannot determine whether these are transient sources. name RA (J2000) Dec (J2000) Comment rmag imag S241125n_X2_O1 3:53:20.4510 +69:33:06.688 Point Src 22.3 21.6 S241125n_X2_O2 3:53:19.8100 +69:33:07.471 Extended 24.1 22.6 S241125n_X2_O3 3:53:19.6728 +69:33:13.275 Faint 25.4 26.3 S241125n_X2_O4 3:53:19.0313 +69:33:10.008 Faint 25.4 24.6 S241125n_X2_O5 3:53:21.1088 +69:33:11.602 Point Src 18.9 18.4 The reported magnitudes are not corrected for the Milky Way galactic extinction value of E(B-V) = 0.4678 mag (Schlafly & Finkbeiner 2011). Further observations are planned. We thank Ryan Howie and Benjamin Weiner at the MMT for the rapid scheduling and execution of these observations. *SAGUARO stands for Searches After Gravitational-waves Using ARizona's Observatories. It is a partnership between the University of Arizona and Northwestern University. View this GCN Circular online at https://gcn.nasa.gov/circulars/38333. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 36325] LIGO/Virgo/KAGRA S241125n: SAGUARO follow-up observations with the MMT
by GCN Circulars 27 Nov '24

27 Nov '24

TITLE: GCN CIRCULAR NUMBER: 38333 SUBJECT: LIGO/Virgo/KAGRA S241125n: SAGUARO follow-up observations with the MMT DATE: 24/11/27 00:47:02 GMT FROM: Manisha Shrestha at University of Arizona <mshrestha1(a)arizona.edu> Jillian C. Rastinejad (NU), Manisha Shrestha (UA), Griffin Hosseinzadeh (UCSD), David J. Sand (UA), Charles D. Kilpatrick (NU), Wen-fai Fong (NU), Bhagya Subrayan (UA), K. Azalee Bostroem (UA), Philip N. Daly (UA), Michael J. Lundquist (Keck), Kerry Paterson (MPIA) report on behalf of the SAGUARO collaboration: We observed the field of the Swift/BAT trigger (DeLauney et al. GCN 38308) discovered within the localization region of the GW event S241125n (LIGO/Virgo/KAGRA GCN 38305) with the Binospec imager and spectrograph mounted on the MMT 6.5-meter telescope on Mount Hopkins, Arizona. We obtain 20x75 s imaging in the r-band at a mid-time of 2024-11-26 08:08:50 UT (1.30 days post-burst) and 30x60 s in the i-band at a mid-time of 2024-11-26 09:13:11 UT (1.34 days post-burst). Observations were taken at an average airmass of 1.3 and seeing of 1.2 - 1.8’’. Our observations covered 68.0 percent of the 5 arcmin BAT localization (DeLauney et al. GCN 38308) and the localization region of XRT source S241125n_X2 (Page et al. GCN 38324). Calibrated to PS1 (Flewelling et al. 2020), our imaging reached limiting magnitudes of r>25.5 mag and i>25.5 mag (3 sigma; AB system). Within the error circle of S241125n_X2, we report magnitudes for 5 sources, as shown in the table below. The bright source (S241125n_X2_O5) is in the PS1 catalog, and the rest are below the PS1 detection limit. Therefore we cannot determine whether these are transient sources. name RA (J2000) Dec (J2000) Comment rmag imag S241125n_X2_O1 3:53:20.4510 +69:33:06.688 Point Src 22.3 21.6 S241125n_X2_O2 3:53:19.8100 +69:33:07.471 Extended 24.1 22.6 S241125n_X2_O3 3:53:19.6728 +69:33:13.275 Faint 25.4 26.3 S241125n_X2_O4 3:53:19.0313 +69:33:10.008 Faint 25.4 24.6 S241125n_X2_O5 3:53:21.1088 +69:33:11.602 Point Src 18.9 18.4 The reported magnitudes are not corrected for the Milky Way galactic extinction value of E(B-V) = 0.4678 mag (Schlafly & Finkbeiner 2011). Further observations are planned. We thank Ryan Howie and Benjamin Weiner at the MMT for the rapid scheduling and execution of these observations. *SAGUARO stands for Searches After Gravitational-waves Using ARizona's Observatories. It is a partnership between the University of Arizona and Northwestern University. View this GCN Circular online at https://gcn.nasa.gov/circulars/38333. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 36323] LIGO/Virgo/KAGRA S241126dm: Retraction of GW compact binary merger candidate
by GCN Circulars 26 Nov '24

26 Nov '24

TITLE: GCN CIRCULAR NUMBER: 38332 SUBJECT: LIGO/Virgo/KAGRA S241126dm: Retraction of GW compact binary merger candidate DATE: 24/11/26 23:10:33 GMT FROM: Chia-Hsuan Hsiung <sw56540(a)gmail.com> The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: The trigger S241126dm is no longer considered to be a candidate of interest due to data quality issues in the Virgo detector. View this GCN Circular online at https://gcn.nasa.gov/circulars/38332. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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