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

[vsnet-grb-info 41861] EP260214b: OHP/T120 optical observations
by GCN Circulars 15 Feb '26

15 Feb '26

TITLE: GCN CIRCULAR NUMBER: 43752 SUBJECT: EP260214b: OHP/T120 optical observations DATE: 26/02/15 14:06:52 GMT FROM: Christophe Adami at LAM <christophe.adami(a)lam.fr> D. Russeil (LAM/AMU), C. Adami (LAM/Pytheas/AMU), N.A. Rakotondrainibe (LAM), B. Schneider (LAM), J. Balcaen (Pytheas/OHP), Y. Degot-Longhi (Pytheas/OHP), S. Basa (LAM/OHP/Pytheas/AMU), E. Le Floc'h (CEA/Irfu), P. Araigi-hayek (AMU), J. Bourges (AMU), N. Hatchodourian (AMU), E. Lefevre-forjan (AMU), O. Maegey (AMU), P. Montaigne (AMU), C. Rey (AMU), M. Rousse (AMU), B. Sevilla (AMU), H. Subra (AMU), L. Valliccioni (AMU), H. LeCoroller (LAM), M. Ould-elhkim (LAM) report on behalf of a larger collaboration: We observed the field of the EP260214b (Yang et al., GCN 43744) using the T120cm telescope at Observatoire de Haute-Provence (France). We obtained 40 minutes of exposure in the r-band starting at 01:37:37.6 UT on 2026-02-15 (~3.6 hr after the trigger). In the stacked image, the optical counterpart detected by He et al.(GCN 43745), Watson et al. (GCN 43747), and Perez-Fournon et al. (GCN 43750), and measured at a redshift of 1.208 (LeFloch et al., GCN 43749) is visible with a preliminar magnitude of: r = 21.22 +/- 0.13 mag (AB) The photometric calibration was performed using nearby stars from the PanSTARRS catalog and the STDWeb/STDPipe tools (Karpov 2025), is in the AB system, and is not corrected for Galactic extinction. We acknowledge the excellent support from Observatoire de Haute-Provence. View this GCN Circular online at https://gcn.nasa.gov/circulars/43752. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41860] EP260214a: refined analysis of the EP-FXT observation
by GCN Circulars 15 Feb '26

15 Feb '26

TITLE: GCN CIRCULAR NUMBER: 43751 SUBJECT: EP260214a: refined analysis of the EP-FXT observation DATE: 26/02/15 13:22:15 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> A. Li (BNU), J. Yang (ZZU), Y. H. Jiang (NJU), Y. Liu (NAOC) on behalf of the Einstein Probe (EP) team: The fast X-ray transient EP260214a triggered the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission (Li et al., GCN 43742). It was followed by Global MASTER-Net (Lipunov et al., GCN 43743) and SVOM-VT (Li et al., GCN 43746). The refined analysis of the WXT data shows that the event started at T0=2026-02-14T20:37:00 (UTC), and lasted for approximately 60 seconds. The average WXT 0.5-4 keV spectrum can be fitted with an absorbed power law with a fixed Galactic hydrogen column density of 4.6×10^20 cm^-2 and a photon index of 0.8 (-0.6/+0.7). The derived average unabsorbed 0.5-4 keV flux is 9.7 (-0.3/+0.4) × 10^(-11) erg/s/cm^2. The autonomous observation by the Follow-up X-ray Telescope (FXT) was performed at 2026-02-14T20:39:31 (UTC), 2.5 minutes after T0. The effective exposure time of the observation is around 3.3 ks. On-ground analysis of the FXT data found an uncatalogued source at R.A. = 201.2305, DEC = -29.0431 (J2000) with an uncertainty of 10 arcsec in radius (90% C.L. statistical and systematic). The average 0.5-10 keV spectrum can be fitted with an absorbed power law with a fixed Galactic hydrogen column density of 1.6 × 10^20 cm^-2, and a photon index of 2.3 (-0.3/+0.3). The derived average unabsorbed 0.5-10 keV flux is 1.4 (-0.1/+0.2) ×10^(-11) erg/s/cm^2. The uncertainties are at the 90% confidence level for the above parameters. Further FXT follow-up observations have been arranged. 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/43751. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41859] EP260214b: LCO optical counterpart detection
by GCN Circulars 15 Feb '26

15 Feb '26

TITLE: GCN CIRCULAR NUMBER: 43750 SUBJECT: EP260214b: LCO optical counterpart detection DATE: 26/02/15 11:37:27 GMT FROM: Ismael Perez-Fournon at Instituto de Astrofisica de Canarias <ipf(a)iac.es> I. Pérez-Fournon (IAC and ULL), F. Poidevin (IAC and ULL), D. Cano-Morales, A.E. Hernández-Díaz, I. Correa-Plasencia, E. Lekaroz-Urriza, M. Quintana-Ansaldo (all ULL), A. López-Oramas (IAC and ULL), and D. Aguado (IAC and ULL) Following the detection of the fast X-ray transient EP260214b (Yang et al., GCN #43744), we observed the field with one of the two Las Cumbres Observatory (LCO) 1-m telescopes located at the LCO node at McDonald Observatory, Texas. The observation consisted of a single exposure of 500 sec in the SDSS r' filter, that started on 2026-02-15 at 09:24:15 UT, about 11.34 hours after the EP trigger. The optical counterpart detected by He et al. (GCN #43745) and Watson et al. (GCN #43747) at a resdhift z = 1.208 (Le Floch et al., GCN #43749) is clearly detected in our image with an AB magnitude of r' = 21.28 +/- 0.09, calibrated against PanSTARRS-1 DR2 stars and not corrected for Galactic extinction. This work makes use of observations from the Las Cumbres Observatory global telescope network (LCO program IAC2026A-011, SGLF and Superluminous Supernovae surveys). This work made use of the Astro-COLIBRI platform (P. Reichherzer et al. 2021, ApJS, 256, 5). View this GCN Circular online at https://gcn.nasa.gov/circulars/43750. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41858] EP260214b: VLT/X-shooter spectroscopic redshift z = 1.208
by GCN Circulars 15 Feb '26

15 Feb '26

TITLE: GCN CIRCULAR NUMBER: 43749 SUBJECT: EP260214b: VLT/X-shooter spectroscopic redshift z = 1.208 DATE: 26/02/15 10:06:03 GMT FROM: Aishwarya L Thakur at INAF-IAPS, Rome <aishth(a)outlook.com> E. Le Floch (CEA/Irfu), J. An (NAOC), A. Saccardi (CEA/Irfu), A. L. Thakur (INAF-IAPS), D. Xu (NAOC), L. Cotter (UCD), D. Malesani (DAWN/NBI and Radboud), N. R. Tanvir (U. Leicester) report on behalf of the Stargate collaboration We observed the optical counterpart (He et al. GCN 43745; Watson et al. GCN 43747) of EP260214b (Yang et al. GCN 43744) using the ESO/VLT UT3 (Melipal) equipped with the X-shooter spectrograph. Our spectra cover the wavelength range 3000-21000 Å and consist of 4 exposures of 600 s each. Observations started on 2026 February 15 at 06:24:46 UT (at 8.35 hr post-trigger). In a preliminary reduction of the spectra, we detect continuum over the entire wavelength range. From the detection of multiple absorption lines, which we interpret as the Al II, Fe II, Mg II, we infer a redshift of z = 1.208. Additionally, at a consistent redshift (z = 1.207) we note the presence of several emission lines due to the [O II] doublet, Ne III, the [O III] doublet, and the Balmer lines from the GRB host galaxy. We acknowledge the excellent support of the ESO observing staff in Paranal, in particular Celia Desgrange, Mar Carretero Castrillo, Diego Parraguez and Fuyan Bian. The analysis of this spectrum was carried out with the help of the zHunter tool (https://doi.org/10.5281/zenodo.15189495) View this GCN Circular online at https://gcn.nasa.gov/circulars/43749. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41857] GRB 260211A: SVOM/VT optical counterpart
by GCN Circulars 15 Feb '26

15 Feb '26

TITLE: GCN CIRCULAR NUMBER: 43748 SUBJECT: GRB 260211A: SVOM/VT optical counterpart DATE: 26/02/15 06:50:08 GMT FROM: Huali Li at at NAOC, SVOM <lhl(a)nao.cas.cn> H. L. Li, Y. N. Ma, C. Wu, Z. H. Yao, Y. L. Qiu, L. P. Xin, X. H. Han, J. Wang, Y. Xu, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, L. Lan, J. R. Xu, J. S. Deng, J. Y. Wei (NAOC), J. Palmerio (CEA/Irfu), R. C. Chen (NJU), A. Li (BNU), W. K. Zheng (UCB) report on behalf of the SVOM/VT team. SVOM/VT performed further ToO observations to GRB260211A detected by SVOM/Eclairs (sb26021102, Gotz et al., GCN 43705) and Fermi GBM (Hamburg et al., GCN 43713). The observation started at 2026-02-14T11:37:39 UTC, i.e., 2.676 days post trigger in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. The source 1 reported in Li et al. (GCN 43720) with coordinations R.A., Dec. (2000)= 86.978758, -0.450528 degrees was fading from 22.5+/-0.3 mag at 2.35 hours to 23.5 +/-0.3 mag at 2.79 days in VT_R channel. The temporal slope is roughly -0.27. Given that the VT source 1 was fading and located within the error box of EP-FXT EPF_J054755.7-002705 (Liang et al., GCN 43721), we propose it is the optical counterpart of the burst. Our photometry was not corrected for Galactic extinction. The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. VT was jointly developed by Xi'an Institute of Optics and Precision Mechanics (XIOPM), CAS and National astronomical observatories (NAOC), CAS. View this GCN Circular online at https://gcn.nasa.gov/circulars/43748. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41856] EP260214b: COLIBRÍ optical observations
by GCN Circulars 15 Feb '26

15 Feb '26

TITLE: GCN CIRCULAR NUMBER: 43747 SUBJECT: EP260214b: COLIBRÍ optical observations DATE: 26/02/15 06:40:56 GMT FROM: Alan Watson at UNAM <alan(a)astro.unam.mx> Alan M. Watson (UNAM), Damien Dornic (CPPM), Rosa L. Becerra (UNAM), Noémie Globus (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Edilberto Aguilar-Ruiz (UNAM), Jean-Luc Atteia (IRAP), Camila Angulo (UNAM), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Nathaniel R. Butler (ASU), Jean-Grégoire Ducoin (CPPM), Francis Fortin (IRAP), Leonardo García García (UNAM), Ramandeep Gill (UNAM), Asuka Kuwata (UNAM), Nikos Mandarakas (LAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Fredd Sánchez Álvarez (UNAM), Benjamin Schneider (LAM), and Antonio de Ugarte Postigo (LAM) report: We imaged the field of EP260214b (Yang et al., GCN Circ. 43744) using the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope. We observed from 2026-02-15 05:49 to 06:12 UTC (from 7.76 to 8.13 hours after the trigger) and obtained 3, 7, 2, and 12 minutes of exposure, respectively, in the g, r, i, and z filters. The data were reduced, calibrated, and analyzed with the COLIBRÍ ASU pipeline. The photometry was calibrated using nearby stars from the PanSTARRS DR1 catalog, is in the AB system, and is not corrected for Galactic extinction. We detect the optical counterpart reported by He et al. (GCN Circ. 43745), at preliminary magnitudes of: g = 21.30 +/- 0.09, r = 21.11 +/- 0.07, i = 21.08 +/- 0.14, and z = 21.29 +/- 0.18. Comparing our r-band magnitude to the one reported by He et al. (GCN Circ. 43745) at about 2.2 hours, the source has faded only slowly with a temporal power law index of about alpha ≈ -0.15, which suggests the presence of a plateau. We also notice that the optical counterpart has blue colors, which are consistent with a nearby event and also consistent with the high X-ray flux reported by Yang et al. (GCN Circ. 43744). Further observations and analysis are ongoing. We encourage spectroscopic observations of this source to confirm its redshift. We thank the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir and the COLIBRÍ and DDRAGO engineering teams. COLIBRÍ is an astronomical observatory developed and operated jointly by France (AMU, CNES and CNRS) and Mexico (UNAM and SECIHTI). It is located at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir, Baja California, Mexico. View this GCN Circular online at https://gcn.nasa.gov/circulars/43747. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41855] EP260214a: SVOM/VT optical upper limits
by GCN Circulars 15 Feb '26

15 Feb '26

TITLE: GCN CIRCULAR NUMBER: 43746 SUBJECT: EP260214a: SVOM/VT optical upper limits DATE: 26/02/15 06:31:32 GMT FROM: Huali Li at at NAOC, SVOM <lhl(a)nao.cas.cn> H. L. Li, Y. N. Ma, L. P. Xin, Y. L. Qiu, C. Wu, Z. H. Yao, X. H. Han, Y. Xu, J. Wang, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, L. Lan, J. R. Xu, J. S. Deng, J. Y. Wei (NAOC), J. Palmerio (CEA) report on behalf of the SVOM/VT team. SVOM/VT performed a Target of Opportunity observation of EP260214a detected by Einstein Probe (Li et al., GCN 43742). The observation started on 2026-02-14T23:12:55 UTC, 2.58 hours after the trigger, in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. No uncatalogued sources were detected in stacked images within the error box of EP-FXT (Li et al., GCN 43742). The 3 sigma limit magnitudes are derived as follows: Mid time | Band | Exposure Time | 3 sigma limit magnitude 3.60 hours VT_B 56*50 sec > 23.6 mag 3.60 hours VT_R 50*50 sec > 23.3 mag Our photometry was in AB magnitude and was not corrected for Galactic extinction. The nondetection is consistent with the result from MASTER (Lipunov et al., GCN 43743). The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. VT was jointly developed by Xi'an Institute of Optics and Precision Mechanics (XIOPM), CAS and National astronomical observatories (NAOC), CAS. View this GCN Circular online at https://gcn.nasa.gov/circulars/43746. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41854] EP260214b: NOT optical counterpart detection
by GCN Circulars 15 Feb '26

15 Feb '26

TITLE: GCN CIRCULAR NUMBER: 43745 SUBJECT: EP260214b: NOT optical counterpart detection DATE: 26/02/15 05:27:38 GMT FROM: L. B. He at NAOC <helb(a)bao.ac.cn> L.B. He, Z.P. Zhu, J. An, X. Liu, S.Q. Jiang, D. Xu (NAOC), S.Y. Fu (HUST), J.P.U. Fynbo (DAWN/NBI), K. Valeckas (NOT) report on behalf of a large collaboration: We observed the field of EP260214b detected by EP/WXT (Yang et al., GCN 43744) using the 2.56-m Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. In a single of 220 s Sloan r-band exposure we detect a brightened source within the EP/FXT error circle (Yang et al., GCN 43744) at coordinates: R.A.(J2000) = 12:45:01.96 = 191.2582 Dec.(J2000) = 23:51:13.10 = 23.8536 with an uncertainty of ~0.5 arcsec. We measure r' = 20.90 +/- 0.04 at ~2.22 hrs post-trigger, calibrated with Pan-STARRS1-dr2 catalog and not corrected for Galactic extinction. The source is brighter than its underlying host galaxy by ~2.0 mag, and the galaxy has a photometric redshift z ~ 1.04 from Legacy Survey dr9. We suggest the source is the optical counterpart of EP260214b. View this GCN Circular online at https://gcn.nasa.gov/circulars/43745. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41853] EP260214b: Einstein Probe detection of a fast X-ray transient
by GCN Circulars 15 Feb '26

15 Feb '26

TITLE: GCN CIRCULAR NUMBER: 43744 SUBJECT: EP260214b: Einstein Probe detection of a fast X-ray transient DATE: 26/02/15 05:11:36 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> J. Yang (ZZU), A. Li (BNU), Y. H. Jiang (NJU) and Y. Liu (NAOC) on behalf of the Einstein Probe (EP) team: We report on the detection of a fast X-ray transient by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission, designated EP260214b. The transient triggered EP-WXT (ID: 01709258389) at 2026-02-14T22:04:12 (UTC). The WXT position of the source is R.A. = 191.260 deg, DEC = 23.857 deg (J2000) with an uncertainty of 3 arcmin in radius (90% C.L. statistical and systematic). The preliminary analysis of the WXT data shows that the event started at T0=2026-02-14T22:03:34 (UTC), and lasted for approximately 50 seconds. The average WXT 0.5-4 keV spectrum can be fitted with an absorbed power law with a fixed Galactic hydrogen column density of 1.57 × 10^20 cm^-2 and a photon index of 0.7 (+/-0.4). The derived average unabsorbed 0.5-4 keV flux is 2.1 (-0.5/+0.7) × 10^(-9) erg/s/cm^2. As the EP was performing another autonomous follow-up observation, no follow-up observation was performed automatically for this source. A follow-up observation with the Follow-up X-ray Telescope (FXT) was performed at 2026-02-15T03:59:57 (UTC), about 6 hours after T0. Within the WXT error circle, the FXT on-board alert indicated an uncatalogued X-ray source at R.A. = 191.2598 deg, DEC = 23.8533 deg (J2000) with an uncertainty of 20 arcsec in radius (90% C.L. statistical and systematic). 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/43744. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41852] EP260214a: Global MASTER-Net observations report
by GCN Circulars 15 Feb '26

15 Feb '26

TITLE: GCN CIRCULAR NUMBER: 43743 SUBJECT: EP260214a: Global MASTER-Net observations report DATE: 26/02/15 03:18:24 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 EP260214a ( EP Team et al., GCN 43742) errorbox 268 sec after notice time and 21982 sec after trigger time at 2026-02-15 02:44:26 UT, with upper limit up to 17.3 mag. Observations started at twilight. The observations began at zenith distance = 76 deg. The sun altitude is -16.0 deg. The galactic latitude b = 33 deg., longitude l = 312 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3136874 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 22012 | 2026-02-15 02:44:26 | MASTER-Kislovodsk | (13h 24m 58.40s , -28d 29m 17.5s) | C | 60 | 17.3 | 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/43743. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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