November 2025 - vsnet-grb-info - ooruri.kusastro.kyoto-u.ac.jp

[vsnet-grb-info 40872] GRB 251122A / EP251122a: LCO optical upper limits
by GCN Circulars 22 Nov '25

22 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42804 SUBJECT: GRB 251122A / EP251122a: LCO optical upper limits DATE: 25/11/22 16:36:43 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> A. Saccardi (CEA/Irfu), D. B. Malesani (DAWN/NBI and Radboud), L. P. Xin (NAOC), D. Turpin, J. T. Palmerio (CEA/Irfu), C. Wu (NAOC), B. Cordier (CEA/Irfu), Z.-Y. Lin, C. Lachaud (APC), report on behalf of the SVOM mission team: We observed the field of GRB 251122A / EP251122a detected by SVOM/ECLAIRs (Lin et al. GCN 42800) and EP/WXT (Wang et al., GCN 42799) with the LCO 1m telescope at the Siding Spring Observatory equipped with the Sinistro instrument. Our observation started at 2025-11-22T14:56:27 (UTC) about 1 hour after the trigger. We obtained 3x200 s exposures in each of the SDSS r and Pan-STARRS z filters. The r-band images are unfortunately trailed, which reduces our sensitivity. In the stacked images, we do not detect any new optical source within the EP/FXT and SVOM/MXT error circles. We measure the following 3-sigma upper limits calibrated against the Pan-STARRS catalog, and not corrected for Galactic extinction: r > 20.8 AB (mid time 80 min after the SVOM T0); z > 20.4 AB (mid time 63 min after the SVOM T0). Our results are consistent with the limits reported by Wu et al. (GCN 42801). We do not detect the candidate counterpart reported by Cheng et al. (GCN 42803), which is fainter and reported at an earlier epoch than our observations. This project is funded by the SVOM collaboration. View this GCN Circular online at https://gcn.nasa.gov/circulars/42804. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40871] EP251122a / GRB 251122A: optical counterpart candidate with Kinder observations
by GCN Circulars 22 Nov '25

22 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42803 SUBJECT: EP251122a / GRB 251122A: optical counterpart candidate with Kinder observations DATE: 25/11/22 16:25:24 GMT FROM: Amar Aryan at National Central University, Institute of Astronomy (NCUIA) <amararyan941(a)gmail.com> Y.-C. Cheng (NCU), J.Y.B Choo (UKM), A.N. Garcia (PUP), A.L.A.M. Nasir (UniSZA), J.-L. Yang (NCU) on behalf of the 47th International School for Young Astronomers (ISYA) in Taipei, A. Aryan, T.-W. Chen, Y.-H. Lee, C.-S. Lin (all NCU), S. Yang (HNAS), A. K. H. Kong (NTHU), J. Gillanders, S. J. Smartt (both Oxford), Y. J. Yang (NYUAD), A. Sankar.K, Y.-C. Pan, C.-C. Ngeow, M.-H. Lee, C.-H. Lai, W.-J. Hou, H.-C. Lin, H.-Y. Hsiao, J.-K. Guo (all NCU), Z. N. Wang, L. L. Fan, G. H. Sun (all HNAS), H.-W. Lin (UMich), H. F. Stevance, S. Srivastav, L. Rhodes (all Oxford), M. Nicholl, M. Fulton, T. Moore, K. W. Smith, C. Angus, A. Aamer (all QUB), A. Schultz and M. Huber (both IfA, Hawaii) report: We observed the field of the fast X-ray transient EP251122a (Wang et al., GCN 42799) using the 1m LOT at Lulin Observatory in Taiwan as part of the Kinder collaboration (Chen & Yang et al., 2025, ApJ, 983, 86, doi:10.3847/1538-4357/adb428). A follow-up observation by SVOM found a temporally and spatially coincident long GRB 251122A (Lin et al. GCN 42800). The first LOT epoch of observations began at 14:13 UTC on the 22nd of November 2025 (MJD 61001.592), 0.31 hr after the EP-WXT trigger. We used the Kinder pipeline (Yang et al. A&A 646, A22) to stack the images and perform template subtraction with the DESI Legacy Survey (Dey et al. 2019, AJ 157, 168) DR10 image. In the difference image, we find a faint, uncataloged optical counterpart candidate at RA, DEC = 02:32:05.1284, +14:07:43.826; lying within the 20" EP-FXT localization circle. The counterpart candidate is likely associated with the DESI Legacy Survey (DR10) galaxy at RA, Dec = 38.0213, 14.1289, with r = 24.64 mag and a photometric redshift of 1.113 ± 0.368. We perform PSF photometry on the position of the source with the stacked frames. The details of the observations and measured PSF magnitude (in the AB system) of the proposed counterpart of EP251122a are as follows: Telescope | Filter | MJD (start) | t-t0 (hr) | Exposure (s) | Magnitude | avg. Seeing | med. Airmass LOT | r | 61001.592 | 0.31 | 300 * 6 | 23.1 +/- 0.2 | 0".93 | 1.01 We caution that the optical counterpart candidate is detected at a level close to the detection limit (>23.2 mag). Our observation is consistent with Wu et al. (GCN 42801) and deeper than their limits. The presented magnitude is calibrated using the field stars from the Pan-STARRS1 DR2 and is not corrected for the expected Galactic foreground extinction of A_r = 0.35 mag in the direction of the transient (Schlafly & Finkbeiner 2011). The methodology, details on the Lulin observatory telescopes, and a compilation of our optical follow-up campaign for FXTs discovered within the first year of operation of the Einstein-Probe mission can be found in Aryan et al. 2025, ApJS, 281, 20, doi:10.3847/1538-4365/adfc69. View this GCN Circular online at https://gcn.nasa.gov/circulars/42803. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40870] EP251122a: Global MASTER-Net observations report
by GCN Circulars 22 Nov '25

22 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42802 SUBJECT: EP251122a: Global MASTER-Net observations report DATE: 25/11/22 16:09:30 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-Kislovodsk robotic telescope [1] located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) was pointed to the EP251122a ( EP Team et al., GCN 42799) errorbox 3880 sec after notice time and 5537 sec after trigger time at 2025-11-22 15:26:08 UT, with upper limit up to 19.3 mag. The observations began at zenith distance = 60 deg. The sun altitude is -18.9 deg. The galactic latitude b = -42 deg., longitude l = 157 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3049413 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 5627 | 2025-11-22 15:26:08 | MASTER-Kislovodsk | (02h 30m 23.79s , +14d 20m 55.2s) | C | 180 | 16.9 | 5628 | 2025-11-22 15:26:08 | MASTER-Kislovodsk | (02h 30m 33.71s , +13d 58m 00.6s) | C | 180 | 17.8 | 7537 | 2025-11-22 15:57:58 | MASTER-Kislovodsk | (02h 30m 49.90s , +14d 17m 52.7s) | C | 180 | 18.7 | 7539 | 2025-11-22 15:58:00 | MASTER-Kislovodsk | (02h 31m 02.20s , +13d 55m 05.3s) | C | 180 | 19.3 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. [1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp. http : // www.pereplet.ru/lipunov/625.html View this GCN Circular online at https://gcn.nasa.gov/circulars/42802. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40869] GRB 251122A/EP251122a: SVOM/C-GFT upper limit
by GCN Circulars 22 Nov '25

22 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42801 SUBJECT: GRB 251122A/EP251122a: SVOM/C-GFT upper limit DATE: 25/11/22 16:06:03 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> Chao WU (NAOC), Zhe Kang (CHO), Liping Xin(NAOC), Xuhui Han(NAOC), Pinpin Zhang (NAOC), Xiaomeng Lu (NAOC), Zhenwei Li (CHO), You Lv (CHO), Ruosong Zhang (NAOC), Yujie Xiao(NAOC), Yulei Qiu(NAOC), Jing Wang (NAOC), Jinsong Deng(NAOC), Lei Huang(NAOC), Jianyan Wei (NAOC), Z.-Y. Lin, C. Lachaud (APC) report on behalf of the SVOM/C-GFT team: We observed the field of GRB 251122A detected by EP/WXT(Wang et al., GCN 42799, ID:01709248658) and SVOM/ECLAIRs (Lin et al., GCN 42800, SVOM burst-id sb25112204) with LATIOS on SVOM/C-GFT. Observations started at 2025-11-22T13:59:06 UTC, ~118 seconds after the trigger. A series of g, r, and i band images were obtained. No credible candidate was detected within the error box provided by EP/FXT (Wang et al., GCN 42799) and SVOM/MXT (Lin et al., GCN 42800 ) in our images after preliminary processing, the three sigma upper limit is: | Date-Obs (mid-time) | Mid_t - T0 (s) | Exposure Time (s) | Band | Upper Limit (AB) | |---------------------|----------------|-------------------|------|------------------| | 2025-11-22T13:59:45 | 157 | 6×10 | i | 20.05 | The photometry was calibrated against nearby UCAC4 catalogue and no correction for Galactic dust extinction was applied. We thank the observation assistants Bowen Li and Hongyan Xue at Jilin observatory for their excellent support. The Chinese Ground Follow-up Telescope (C-GFT) for the SVOM mission is located at Jilin Station, Changchun Observatory, National Astronomical Observatories, CAS. It features two instruments: (1) CATCH at the Cassegrain focus with a 21 arcsec x 21 arcsec FOV for simultaneous g/r/i-band imaging, and (2) LATIOS, a 4k x 4k CMOS camera at the prime focus with a 1.28 deg x 1.28 deg FOV that images in g, r, and i bands via filter switching. View this GCN Circular online at https://gcn.nasa.gov/circulars/42801. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40868] GRB 251122A / EP251122a: SVOM detection of a long burst
by GCN Circulars 22 Nov '25

22 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42800 SUBJECT: GRB 251122A / EP251122a: SVOM detection of a long burst DATE: 25/11/22 14:26:21 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> Z.-Y. Lin, C. Lachaud (APC), S. Schanne, D. Turpin (CEA/Irfu), T. Maiolino (LUPM), D. Götz (CEA/Irfu), D. B. Malesani (DAWN/NBI and Radboud) report on behalf of the SVOM team: At 2025-11-22T13:57:08 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 251122A (SVOM burst-id sb25112204), also triggered by EP/WXT as EP251122a (Wang et al., GCN 42799). The following trigger information was received on the ground with low latency by the SVOM VHF Alert Network. The burst was only detected by the Image Trigger (IMT), which produced a sequence of 6 alerts. IMT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 10.68 in the [5-20] keV energy band over a time window of 327.68 seconds starting at 2025-11-22T13:52:01. The localization of the best alert is R.A., Dec. 38.1450, 14.0645 degrees (J2000) with a 90% confidence level (C.L.) radius of 7.48 arcmin (including systematic error of 2 arcmin added in quadrature). SVOM slewed to the burst. SVOM/MXT began observing the field at 2025-11-22T14:00:05 UTC, 177 seconds after T0. Using onboard processed data we found an uncatalogued X-ray source located at R.A., Dec. 38.026, +14.124 degrees: R.A. (J2000) = 02h32m06s Dec. (J2000) = +14d07m26s with a 90% C.L. radius of 75 arcseconds. This location is 7.8 arcminutes from the ECLAIRs onboard position. This position may be improved as more data is received. VT began observing the field after the slew. The analysis of the data will be published in a future circular. 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. SVOM/ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC. SVOM/GRM was developed by the Institute of High Energy Physics (IHEP) of CAS. SVOM/MXT was developed jointly by CNES, CEA-IRFU, CNRS-IJCLab, University of Leicester, MPE. The Burst Advocate (BA) on shift for this alert is Zheyu Lin: zheyu.lin(a)apc.in2p3.fr. Please contact the BA by email if you require additional information. View this GCN Circular online at https://gcn.nasa.gov/circulars/42800. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40867] EP251122a: Einstein Probe detection of an X-ray transient
by GCN Circulars 22 Nov '25

22 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42799 SUBJECT: EP251122a: Einstein Probe detection of an X-ray transient DATE: 25/11/22 14:20:22 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> B.-T. Wang (YNAO), Y.-H. I. Yin (HKU), G. J. Yang (NAOC), H.-Z. Wu (HUST) and W. D. Zhang (NAOC) on behalf of the Einstein Probe (EP) team: We report on the detection of an X-ray transient by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission, designated EP251122a. The transient triggered EP-WXT (ID: 01709248658) at 2025-11-22T13:53:51 (UTC). The WXT position of the source is R.A. = 38.017 deg, DEC = 14.132 deg (J2000) with an uncertainty of 3 arcmin in radius (90% C.L. statistical and systematic). A follow-up observation with the Follow-up X-ray Telescope (FXT) was performed automatically. Within the WXT error circle, an uncatalogued X-ray source was detected at R.A. = 38.0199 deg, DEC = 14.1277 deg (J2000) with an uncertainty of 20 arcsec in radius (90% C.L. statistical and systematic). Further information will be updated when the telemetry data is received. 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/42799. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40866] EP251118a: Continued Optical Detection with Kinder observations
by GCN Circulars 22 Nov '25

22 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42798 SUBJECT: EP251118a: Continued Optical Detection with Kinder observations DATE: 25/11/22 13:04:05 GMT FROM: Amar Aryan at National Central University, Institute of Astronomy (NCUIA) <amararyan941(a)gmail.com> A. Aryan, T.-W. Chen, Y.-H. Lee, C.-S. Lin (all NCU), A. K. H. Kong (NTHU), J. Gillanders, S. J. Smartt (both Oxford), Y. J. Yang (NYUAD), A. Sankar.K, Y.-C. Pan, C.-C. Ngeow, M.-H. Lee, C.-H. Lai, W.-J. Hou, H.-C. Lin, H.-Y. Hsiao, J.-K. Guo (all NCU), S. Yang, Z. N. Wang, L. L. Fan, G. H. Sun (all HNAS), H.-W. Lin (UMich), H. F. Stevance, S. Srivastav, L. Rhodes (all Oxford), M. Nicholl, M. Fulton, T. Moore, K. W. Smith, C. Angus, A. Aamer (all QUB), A. Schultz and M. Huber (both IfA, Hawaii) report: Followed by our previous detection (Lee et al., GCN 42780 ), we continued to observe the field of the fast X-ray transient EP251118a (Jiang et al., GCN 42749) using the 1m LOT at Lulin Observatory in Taiwan as part of the Kinder collaboration (Chen & Yang et al., 2025, ApJ, 983, 86, doi:10.3847/1538-4357/adb428). The first LOT epoch of observations began at 18:09 UTC on November 21, 2025 (MJD 61000.756), 73.45 hours after the EP-WXT trigger. We utilized the astroalign (Beroiz et al. 2020, A&C, 32, 100384) and astropy (Astropy Collaboration et al. 2022, ApJ, 935, 167) packages to align and stack the individual frames. We utilized the Python-based package AutoPhOT (Brennan & Fraser, 2022, A&A, 667, A62) to perform template subtraction with the DESI Legacy Survey (Dey et al. 2019, AJ 157, 168) DR10 image using the 'hotpants' (Becker A., 2015, ascl.soft. ascl:1504.004) algorithm. In the difference image, we onece again clearly detected the optical counterpart candidate proposed by Malesani et al. (GCN 42751) at a spectroscopic redshift of z = 1.216 (An et al., GCN 42756), and confirmed by Belkin et al. (GCN 42758); Yadav et al. (GCN 42760); Busmann et al. (GCN 42763); Francile et al. (GCN 42767); Urquijo-Rodríguez et al. (GCN 42773); Moskvitin et al. (GCN 42785); Gupta et al. (GCN 42787); and Liu et al (GCN 42793) Moreover, we further utilized AutoPhOT to perform the PSF photometry. The details of the observations and the measured magnitude(in the AB system) are as follows: Telescope | Filter | MJD (start) | t-t0 (hr) | Exposure (s) | Magnitude | avg. Seeing | med. Airmass LOT | r | 61000.756 | 73.45 | 300 * 6 | 22.5 +/- 0.1 | 0".92 | 1.12 The presented magnitude is calibrated using the field stars from the ATLAS-RefCat2 catalog from MAST (Tonry J. L. et al. 2018, ApJ, 867, 105) and is not corrected for the expected Galactic foreground extinction of A_r = 0.09 mag in the direction of the transient (Schlafly & Finkbeiner 2011). The methodology, details on the Lulin observatory telescopes, and a compilation of our optical follow-up campaign for FXTs discovered within the first year of operation of the Einstein-Probe mission can be found in Aryan et al. 2025, ApJS, 281, 20, doi:10.3847/1538-4365/adfc69. View this GCN Circular online at https://gcn.nasa.gov/circulars/42798. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40865] LIGO/Virgo/KAGRA S251105aj: SVOM/ECLAIRs detection of a high-energy transient through targeted search
by GCN Circulars 22 Nov '25

22 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42797 SUBJECT: LIGO/Virgo/KAGRA S251105aj: SVOM/ECLAIRs detection of a high-energy transient through targeted search DATE: 25/11/22 10:00:14 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> H. Yang, O. Godet, J.-L. Atteia, M. Brunet, S. Guillot (IRAP), M. Pillas (IAP), L. P. Xin, Y. N. Ma (NAOC) Using the event-by-event data downloaded through the X-band ground stations, we report on the identification of a faint SVOM/ECLAIRs transient detected at 2025-11-05T13:00:48.34 UTC (T0), 88.4 s after the compact binary merger candidate S251105aj (The LIGO-Virgo-Kagra Collaboration, GCN 42587). This transient was detected through an offline targeted search for possible counterparts of the GW event S251105aj. The ECLAIRs source was detected with a timescale of 82 s and below 60 keV, with a best signal-to-noise ratio of 6.1 starting at T0. The localization of the source is RA, Dec = 349.998, -29.022 degrees: RA (J2000) = 23h20m00s Dec (J2000) = -29d01m19s with a 90% C.L. radius of 13.9 arcmin (including a systematic error of 6 arcmin added in quadrature). This position is about 2 degrees outside the 99% area contour of the Bilby.multiorder.fits skymap of S251105aj. At the time of the GW trigger, ECLAIRs was covering 88% of the skymap 99% area. The time-averaged spectrum from T0 to T0+82 s in the energy range of 5-60 keV is well fitted by a blackbody (BB) model, with a measured temperature of 7.8 (+1.5/-1.2) keV. With this model, the total 4-120 keV flux is (3.6+/-0.8)e-9 erg/cm^2/s. Assuming a distance of 2071 Mpc (z=0.374) for the source, this corresponds to a luminosity of 1.8e48 erg/s and a BB emission radius of 1.9e6 cm. A broken power-law model is also tested, providing a comparable fit, though with less well-constrained parameters of photon index 1 around -0.5, break energy of 22 (+21/-10) keV, and photon index 2 around 2.9. At this stage, the nature of this transient is unknown. We conducted SVOM/VT and EP/FXT follow-up observations on this field. The results will be published in dedicated circulars. 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 source is: Hui Yang (IRAP) (hui.yang(a)irap.omp.eu) View this GCN Circular online at https://gcn.nasa.gov/circulars/42797. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40864] LIGO/Virgo/KAGRA S251112cm: SOAR spectroscopy of three TROVE TNS candidates
by GCN Circulars 22 Nov '25

22 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42796 SUBJECT: LIGO/Virgo/KAGRA S251112cm: SOAR spectroscopy of three TROVE TNS candidates DATE: 25/11/22 07:28:12 GMT FROM: Hemanth kumar <hemanth.bommireddy195(a)gmail.com> Hemanth Bommireddy (U de Chile), Regis Cartier (UA), Felipe Olivares (U Hawaii), reporting on behalf of the Dark Energy Survey Gravitational Wave (DESGW) spectroscopy team: We report spectroscopic observations of the transients AT2025adgp, AT2025adhf, and AT2025adhs obtained with the SOAR telescope on 2025-11-14 at 04:10:05 UTC (PI: Bommireddy). For each source, we obtained an exposure of approximately 900s. The spectra were preliminarily reduced and classified using the NGSF spectral classification software (Goldwasser et al. 2022). Based on the reported redshifts (GCN 42675), the top 3 template fits for each event are listed below. | event | SN type/event/instrument (χ²/dof) | | -----------| --------------------------------------------------------------------------- | | AT2025adgp | II/2013fs/KAST (~0.83), Ic-BL/1998bw/DFOSC (~0.82), IIn/2010jl/KAST (~0.82) | AT2025adhf | Ic-BL/1998bw/DFOSC (~1.96), Ic-BL/1998bw/EFOSC2-3.6 (~1.99), Ic-BL/1998bw/DFOSC (~2.06)| | AT2025adhs | SLSN-I/PTF10aagc/LRIS (~1.57), Ia-pec/2000cx/KAST (~1.61), SLSN-I/PTF12dam/DBSP (~1.62)| We thank the SOAR staff for their support during these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/42796. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40863] GRB 251121A: Swift/BAT-GUANO localization skymap of a short burst
by GCN Circulars 22 Nov '25

22 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42795 SUBJECT: GRB 251121A: Swift/BAT-GUANO localization skymap of a short burst DATE: 25/11/22 03:08:50 GMT FROM: Jimmy DeLaunay at Penn State <delauj2(a)gmail.com> Jimmy DeLaunay (PSU), Samuele Ronchini (GSSI), Aaron Tohuvavohu (Cosmic Frontier), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC), Maia Williams (Northwestern) report: Swift/BAT did not localize GRB 251121A onboard (T0: 2025-11-21T16:30:58.99 UTC, Fermi Trig 785435463, Glowbug GCN 42794) The Fermi 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. The BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu 2022, ApJ, 941, 169), performed on the temporal window [T0-20 s, T0+20 s], detects the burst with a sqrt(TS) of 10.7 in a 0.128 s analysis time bin, starting at T0 - 0.032 s. Using the NITRATES analysis, parameter estimation was performed to obtain the localization of this burst in the form of a HEALPIX Multi-Order Coverage (MOC) skymap. This localization accounts for both statistical and systematic errors. More details in the creation and calibration of these maps will soon be published (DeLaunay et al. 2025. in prep) The 90% credible area is 12,627 deg2 and the 50% credible area is 4,629 deg2 The integrated probability inside the coded field of view is 2%. The NITRATES skymap is consistent with the Ferm/GBM localization reported in the final position notice (GCN 42790). The combined Fermi/GBM+NITRATES 90% credible area is 893 deg2 and the 50% credible area is 256 deg2. A plot of the probability skymap can be viewed here: [skymap_plot](https://guano.swift.psu.edu/trigger_report?id=785435495/#:~:te… The probability skymap and joint skymap files can be downloaded from the links here [skymap_fits_file](https://guano.swift.psu.edu/files/785435495/0_n_PROBMAP) [joint_skymap_fits_file](https://guano.swift.psu.edu/files/785435495/0_n_JOI… Instructions on how to read and manipulate this map can be found here: https://guano.swift.psu.edu/documentation More details about this burst can be found on the trigger report page here: https://guano.swift.psu.edu/trigger_report?id=785435495 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/42795. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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