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[vsnet-grb-info 42467] Fermi trigger No 798275385: Global MASTER-Net observations report
by GCN Circulars 19 Apr '26

19 Apr '26

TITLE: GCN CIRCULAR NUMBER: 44345 SUBJECT: Fermi trigger No 798275385: Global MASTER-Net observations report DATE: 26/04/19 07:16:07 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-OAFA robotic telescope [1] located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB260419.30 (trigger No 798275385,20h 50m 14.40s , -47d 41m 24.0s, R=4.3) errorbox 42 sec after notice time and 75 sec after trigger time at 2026-04-19 07:10:56 UT, with upper limit up to 19.4 mag. The observations began at zenith distance = 52 deg. The sun altitude is -48.6 deg. The galactic latitude b = -40 deg., longitude l = 352 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3259527 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 86 | 2026-04-19 07:10:56 | MASTER-OAFA | (20h 49m 30.10s , -47d 58m 25.7s) | C | 20 | 19.4 | 112 | 2026-04-19 07:11:22 | MASTER-OAFA | (20h 49m 30.11s , -47d 58m 24.7s) | C | 20 | 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/44345. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42466] EP260417a: GROWTH-India Telescope optical upper limit
by GCN Circulars 18 Apr '26

18 Apr '26

TITLE: GCN CIRCULAR NUMBER: 44344 SUBJECT: EP260417a: GROWTH-India Telescope optical upper limit DATE: 26/04/18 23:25:30 GMT FROM: V. Swain at IIT Bombay <vishwajeet.s(a)iitb.ac.in> A. Khade (IITB), A. Kumar (IITB), V. Vijaykumar (IITB), T. Mohan (IITB), V. Swain (IITB), D. Eappachen (IIA), S. Patil (IITB), A.P. Saikia (IITB), V. Bhalerao (IITB), G.C. Anupama (IIA), S. Barway (IIA) and R. Norbu (IAO) report on behalf of the GIT team: We observed the field of EP260417a detected by Einstein Probe (Wang et al., GCN 44325), with 0.7m GROWTH-India Telescope (GIT). We started the observation at 2026-04-18 21:01:23 (UTC), i.e., 1.86 days after the trigger, and obtained multiple exposures in the r' filter. No optical counterpart is detected at the position reported by He et al. (GCN 44326) in our stacked image. The photometric upper limit is as follows: | MJD (mid) | Filter | tmid-t0 (hours) | Exposure Time (sec) | Upper limit (AB) | | ------------ | ------ | -------------- | ------------------- | ---------------- | | 61148.885 | r' | 44.85 | 4x360 | 20.64 | The measurement is calibrated against PanSTARRS DR1 (Chambers et al., 2016) and not corrected for Galactic extinction. Our upper limit is consistent with the reported optical measurements by He et al. (GCN 44326) and Lipunov et al. (GCN 44338). The GROWTH India Telescope (GIT; Kumar et al. 2022) is a 70-cm telescope with a 0.7-degree field of view, set up by the Indian Institute of Astrophysics (IIA) and the Indian Institute of Technology Bombay (IITB) with funding from DST-SERB and IUSSTF. It is located at the Indian Astronomical Observatory (Hanle), operated by IIA. We acknowledge funding by the IITB alumni batch of 1994, which partially supports the operations of the telescope. Telescope technical details are available at https://sites.google.com/view/growthindia/. View this GCN Circular online at https://gcn.nasa.gov/circulars/44344. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42465] Fermi GRB 260417B: Global MASTER-Net observations report
by GCN Circulars 18 Apr '26

18 Apr '26

TITLE: GCN CIRCULAR NUMBER: 44343 SUBJECT: Fermi GRB 260417B: Global MASTER-Net observations report DATE: 26/04/18 23:15:27 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-OAFA robotic telescope [1] located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB 260417B ( Fermi GBM team, GCN 44331) errorbox 66043 sec after notice time and 66079 sec after trigger time at 2026-04-18 10:05:14 UT, with upper limit up to 18.4 mag. Observations started at twilight. The observations began at zenith distance = 31 deg. The sun altitude is -11.6 deg. MASTER-SAAO robotic telescope located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB 260417B errorbox 1 days 23747 sec after notice time and 1 days 23783 sec after trigger time at 2026-04-18 22:20:18 UT, with upper limit up to 18.7 mag. The observations began at zenith distance = 48 deg. The sun altitude is -68.6 deg. The galactic latitude b = 1 deg., longitude l = 1 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3256668 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 23203 | 2026-04-17 22:10:08 | MASTER- | (17h 10m 25.00s , -22d 17m 31.5s) | C | 60 | 14.7 | 23280 | 2026-04-17 22:11:25 | MASTER- | (17h 25m 38.80s , -19d 39m 45.5s) | C | 60 | 13.2 | 23367 | 2026-04-17 22:12:52 | MASTER- | (17h 28m 29.57s , -18d 22m 14.8s) | C | 60 | 14.2 | 23445 | 2026-04-17 22:14:10 | MASTER- | (17h 09m 03.19s , -23d 33m 52.4s) | C | 60 | 14.9 | 24134 | 2026-04-17 22:25:39 | MASTER- | (17h 08m 12.30s , -24d 53m 35.2s) | C | 60 | 16.3 | 24217 | 2026-04-17 22:27:02 | MASTER- | (16h 56m 13.19s , -26d 09m 52.5s) | C | 60 | 15.3 | 66109 | 2026-04-18 10:05:14 | MASTER-OAFA | (17h 05m 41.45s , -21d 18m 08.8s) | C | 60 | 18.4 | 66184 | 2026-04-18 10:06:29 | MASTER-OAFA | (17h 14m 24.55s , -21d 19m 32.1s) | C | 60 | 18.0 | 66259 | 2026-04-18 10:07:44 | MASTER-OAFA | (17h 05m 42.90s , -21d 20m 07.9s) | C | 60 | 18.3 | 66335 | 2026-04-18 10:09:00 | MASTER-OAFA | (17h 14m 23.15s , -21d 20m 27.1s) | C | 60 | 18.0 | 66410 | 2026-04-18 10:10:14 | MASTER-OAFA | (17h 05m 44.83s , -21d 18m 07.3s) | C | 60 | 18.1 | 66561 | 2026-04-18 10:12:46 | MASTER-OAFA | (16h 54m 04.36s , -25d 06m 35.0s) | C | 60 | 17.9 | 110213 | 2026-04-18 22:20:18 | MASTER-SAAO | (17h 03m 25.97s , -21d 49m 48.4s) | C | 60 | 18.6 | 110399 | 2026-04-18 22:23:24 | MASTER-SAAO | (17h 17m 53.69s , -21d 35m 09.4s) | C | 60 | 18.1 | 110399 | 2026-04-18 22:23:24 | MASTER-SAAO | (17h 19m 53.70s , -21d 51m 16.9s) | C | 60 | 18.3 | 110492 | 2026-04-18 22:24:57 | MASTER-SAAO | (16h 59m 36.82s , -27d 32m 32.8s) | C | 60 | 17.5 | 110492 | 2026-04-18 22:24:57 | MASTER-SAAO | (16h 57m 30.65s , -27d 16m 26.2s) | C | 60 | 17.7 | 110586 | 2026-04-18 22:26:30 | MASTER-SAAO | (16h 59m 00.63s , -23d 27m 32.8s) | C | 60 | 18.7 | 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/44343. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42464] EP260417b: GROWTH-India Telescope optical upper limit
by GCN Circulars 18 Apr '26

18 Apr '26

TITLE: GCN CIRCULAR NUMBER: 44342 SUBJECT: EP260417b: GROWTH-India Telescope optical upper limit DATE: 26/04/18 22:00:13 GMT FROM: V. Swain at IIT Bombay <vishwajeet.s(a)iitb.ac.in> V. Vijaykumar (IITB), T. Mohan (IITB), V. Swain (IITB), D. Eappachen (IIA), S. Patil (IITB), A.P. Saikia (IITB), V. Bhalerao (IITB), G.C. Anupama (IIA), S. Barway (IIA) and R. Norbu (IAO) report on behalf of the GIT team: We observed the field of EP260417b detected by Einstein Probe (Ni et al., GCN 44323), with 0.7m GROWTH-India Telescope (GIT). We started the observation at 2026-04-18 19:04:51 (UTC), i.e., 1.74 days after the trigger, and obtained a single exposure in the r' filter. We did not detect any transient in our image within the uncertainty region of source position reported by EP. The photometric upper limit is as follows: | MJD (mid) | Filter | tmid-t0 (hours) | Exposure Time (sec) | Upper limit (AB) | | ------------ | ------ | -------------- | ------------------- | ---------------- | | 61149.797 | r' | 41.78 | 420 | 19.3 | The measurement is calibrated against PanSTARRS DR1 (Chambers et al., 2016) and not corrected for Galactic extinction. The GROWTH India Telescope (GIT; Kumar et al. 2022) is a 70-cm telescope with a 0.7-degree field of view, set up by the Indian Institute of Astrophysics (IIA) and the Indian Institute of Technology Bombay (IITB) with funding from DST-SERB and IUSSTF. It is located at the Indian Astronomical Observatory (Hanle), operated by IIA. We acknowledge funding by the IITB alumni batch of 1994, which partially supports the operations of the telescope. Telescope technical details are available at https://sites.google.com/view/growthindia/. View this GCN Circular online at https://gcn.nasa.gov/circulars/44342. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42463] EP260416a: Ondrejov D50 optical detection
by GCN Circulars 18 Apr '26

18 Apr '26

TITLE: GCN CIRCULAR NUMBER: 44341 SUBJECT: EP260416a: Ondrejov D50 optical detection DATE: 26/04/18 19:52:07 GMT FROM: Martin Jelinek at Astro.Inst-AVCR,Ondrejov <martin.jelinek(a)asu.cas.cz> M. Jelinek, J. Strobl, F. Novotny, A. Malenakova and R. Hudec (ASU CAS Ondrejov, CZ) report: We observed the field of EP260416a (Hu et al., GCN 44307) with the 50 cm robotic telescope (D50) of the Astronomical Institute Ondrejov, near Prague, Czech Republic. We obtained a series of 120 s Sloan-r band exposures starting at 20:09 UT on 2026 April 17, i.e. 38.66 h after the initial trigger, and combined 68 frames with a mean exposure time of 40.03 h after the trigger. The optical counterpart (Ducoin et al., GCN 44310; Li et al., GCN 44315; Hua et al., GCN 44318; Lee et al., GCN 44319; Zheng et al., GCN 44321; Martin-Carrillo et al., GCN 44328; Li et al., GCN 44334) is detected in the combined image. The preliminary AB magnitude of the object is r = 21.08 +/- 0.23, calibrated against the ATLAS catalog and not corrected for Galactic extinction. Our measurement is consistent with the continued fading of the afterglow. View this GCN Circular online at https://gcn.nasa.gov/circulars/44341. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42462] GRB 260418B: Fermi GBM Final Real-time Localization
by GCN Circulars 18 Apr '26

18 Apr '26

TITLE: GCN CIRCULAR NUMBER: 44340 SUBJECT: GRB 260418B: Fermi GBM Final Real-time Localization DATE: 26/04/18 16:30:58 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply(a)GIOC.nsstc.nasa.gov> The Fermi GBM team reports the detection of a likely LONG GRB At 16:20:21 UT on 18 Apr 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260418B (trigger 798222026.725586 / 260418681). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 34.7, Dec = -40.5 (J2000 degrees, equivalent to J2000 02h 18m, -40d 30'), with a statistical uncertainty of 4.0 degrees. The angle from the Fermi LAT boresight is 47.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260418681/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260418681/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260418681/… View this GCN Circular online at https://gcn.nasa.gov/circulars/44340. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42461] EP260416a: VLT/FORS2 spectroscopic redshift confirmation
by GCN Circulars 18 Apr '26

18 Apr '26

TITLE: GCN CIRCULAR NUMBER: 44339 SUBJECT: EP260416a: VLT/FORS2 spectroscopic redshift confirmation DATE: 26/04/18 12:32:28 GMT FROM: Laura Cotter at University College Dublin <laura.cotter(a)ucdconnect.ie> J. An (NAOC), A. Saccardi (CEA/Irfu), L. Cotter (UCD), D. Xu (NAOC), D. B. Malesani (DAWN/NBI and Radboud), A. L. Thakur (INAF-IAPS) report on behalf of the Stargate collaboration: We observed the optical counterpart (Ducoin et al., GCN 44310; Li et al., GCN 44315; Hua et al., GCN 44318; Lee et al., GCN 44319; Zheng et al., GCN 44321; Martin-Carrillo et al., GCN 44328; Li et al,. GCN 44334) of EP260416a (Hu et al., GCNs 44307, 44324) using the ESO VLT UT1 (Antu) equipped with the FORS2 spectrograph. Our observation started on 2026 April 18 at 03:04:13 UT (1.90 days after the EP trigger). A series of 3 spectra of 900 s each were obtained with the 300V grism, covering the wavelength range 3500-8600 AA. From a 60 s acquisition image (1.89 days after trigger), we measure a magnitude R = 20.99 +/- 0.06 (Vega), calibrated against nearby stars from the Pan-STARRS catalog using the Lupton (2005) transformations, and not corrected for Galactic extinction. In a preliminary reduction of the spectra, we detect a continuum over the entire wavelength range. At the blue edge of the spectrum, even though the S/N is low, we identify a broad trough at around 3540 AA, likely due to H I. We also detect multiple absorption features including O I, C II, Si IV, C IV, Si II, Fe II, Al II, Al III, at a common redshift of z = 1.910, which we thus suggest to be the redshift of EP260416a. The lack of any further hydrogen absorption at higher redshift implies that the z = 1.910 system is indeed local to the GRB. Our results confirm the tentative redshift measurement reported by He et al. (GCN 44336). We acknowledge expert support from the ESO observing staff in Paranal, particularly Hannah Osborne and Diego Parraguez. 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/44339. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42460] EP260417a: Global MASTER-Net observations report
by GCN Circulars 18 Apr '26

18 Apr '26

TITLE: GCN CIRCULAR NUMBER: 44338 SUBJECT: EP260417a: Global MASTER-Net observations report DATE: 26/04/18 09:45:27 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-OAFA robotic telescope [1] located in Argentina (OAFA observatory of San Juan National University) was pointed to the EP260417a ( EP Team et al., GCN 44325) errorbox 12831 sec after trigger time at 2026-04-17 03:56:53 UT, with upper limit up to 19.9 mag. The observations began at zenith distance = 45 deg. The sun altitude is -67.6 deg. MASTER-OAGH robotic telescope located in Mexico (OAGH National Institute for Astrophysics, Optics and Electronics) was pointed to the EP260417a errorbox 78480 sec after notice time and 1 days 33084 sec after trigger time at 2026-04-18 09:34:26 UT, with upper limit up to 19.2 mag. The observations began at zenith distance = 53 deg. The sun altitude is -36.9 deg. The galactic latitude b = 19 deg., longitude l = 355 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3256324 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 4312 | 2026-04-17 01:34:24 | MASTER- | (16h 25m 32.78s , -22d 27m 07.0s) | C | 60 | 16.8 | 12861 | 2026-04-17 03:56:53 | MASTER-OAFA | (16h 22m 03.10s , -23d 33m 17.7s) | C | 60 | 18.9 | 12921 | 2026-04-17 03:56:53 | MASTER-OAFA | (16h 22m 03.09s , -23d 33m 17.9s) | C | 180 | 19.7 | Coadd 13013 | 2026-04-17 03:59:24 | MASTER-OAFA | (16h 22m 05.31s , -23d 31m 13.7s) | C | 60 | 19.5 | 13243 | 2026-04-17 04:03:14 | MASTER-OAFA | (16h 22m 01.68s , -23d 31m 04.9s) | C | 60 | 19.4 | 13395 | 2026-04-17 04:05:46 | MASTER-OAFA | (16h 22m 02.65s , -23d 33m 00.6s) | C | 60 | 19.5 | 13455 | 2026-04-17 04:05:46 | MASTER-OAFA | (16h 22m 02.65s , -23d 33m 00.5s) | C | 180 | 19.9 | Coadd 15146 | 2026-04-17 04:34:57 | MASTER-OAFA | (16h 22m 04.82s , -23d 30m 29.9s) | C | 60 | 19.6 | 15221 | 2026-04-17 04:36:12 | MASTER-OAFA | (16h 22m 04.76s , -23d 32m 06.6s) | C | 60 | 19.7 | 15297 | 2026-04-17 04:37:28 | MASTER-OAFA | (16h 22m 07.64s , -23d 30m 28.6s) | C | 60 | 19.6 | 15357 | 2026-04-17 04:37:28 | MASTER-OAFA | (16h 22m 07.64s , -23d 30m 28.6s) | C | 180 | 19.9 | Coadd 15613 | 2026-04-17 04:42:44 | MASTER-OAFA | (16h 22m 02.17s , -23d 31m 58.9s) | C | 60 | 19.5 | 15688 | 2026-04-17 04:43:59 | MASTER-OAFA | (16h 22m 07.18s , -23d 31m 53.2s) | C | 60 | 19.5 | 15766 | 2026-04-17 04:45:17 | MASTER-OAFA | (16h 22m 04.70s , -23d 30m 07.5s) | C | 60 | 19.4 | 15826 | 2026-04-17 04:45:17 | MASTER-OAFA | (16h 22m 04.69s , -23d 30m 07.5s) | C | 180 | 19.9 | Coadd 17894 | 2026-04-17 05:20:45 | MASTER-OAFA | (16h 22m 01.37s , -23d 29m 11.6s) | C | 60 | 19.6 | 17967 | 2026-04-17 05:21:59 | MASTER-OAFA | (16h 22m 07.83s , -23d 30m 10.7s) | C | 60 | 19.6 | 18047 | 2026-04-17 05:23:18 | MASTER-OAFA | (16h 22m 00.60s , -23d 31m 09.3s) | C | 60 | 19.6 | 18107 | 2026-04-17 05:23:18 | MASTER-OAFA | (16h 22m 00.60s , -23d 31m 09.3s) | C | 180 | 19.5 | Coadd 18354 | 2026-04-17 05:28:26 | MASTER-OAFA | (16h 22m 07.10s , -23d 29m 32.0s) | C | 60 | 19.2 | 18433 | 2026-04-17 05:29:44 | MASTER-OAFA | (16h 22m 02.40s , -23d 30m 03.3s) | C | 60 | 18.9 | 18509 | 2026-04-17 05:31:00 | MASTER-OAFA | (16h 22m 00.62s , -23d 29m 01.8s) | C | 60 | 18.9 | 18569 | 2026-04-17 05:31:00 | MASTER-OAFA | (16h 22m 00.62s , -23d 29m 01.9s) | C | 180 | 19.4 | Coadd 21141 | 2026-04-17 06:14:52 | MASTER-OAFA | (16h 22m 06.99s , -23d 29m 57.4s) | C | 60 | 19.3 | 21216 | 2026-04-17 06:16:08 | MASTER-OAFA | (16h 22m 01.94s , -23d 30m 56.8s) | C | 60 | 19.2 | 21290 | 2026-04-17 06:17:21 | MASTER-OAFA | (16h 22m 08.44s , -23d 30m 33.6s) | C | 60 | 19.3 | 21350 | 2026-04-17 06:17:21 | MASTER-OAFA | (16h 22m 08.45s , -23d 30m 33.6s) | C | 180 | 19.6 | Coadd 21365 | 2026-04-17 06:18:36 | MASTER-OAFA | (16h 22m 04.86s , -23d 29m 08.6s) | C | 60 | 19.2 | 21439 | 2026-04-17 06:19:50 | MASTER-OAFA | (16h 22m 04.87s , -23d 30m 41.6s) | C | 60 | 18.7 | 21515 | 2026-04-17 06:21:07 | MASTER-OAFA | (16h 22m 08.53s , -23d 29m 14.9s) | C | 60 | 19.4 | 74895 | 2026-04-17 21:10:46 | MASTER- | (16h 16m 30.79s , -20d 56m 12.9s) | C | 60 | 13.1 | 110797 | 2026-04-18 07:09:09 | MASTER-OAFA | (16h 17m 04.14s , -21d 44m 07.5s) | C | 60 | 19.4 | 110874 | 2026-04-18 07:10:25 | MASTER-OAFA | (16h 25m 34.38s , -21d 45m 27.4s) | C | 60 | 19.5 | 110950 | 2026-04-18 07:11:42 | MASTER-OAFA | (16h 16m 57.59s , -21d 43m 52.3s) | C | 60 | 19.5 | 111028 | 2026-04-18 07:12:59 | MASTER-OAFA | (16h 25m 40.71s , -21d 45m 23.9s) | C | 60 | 19.5 | 111103 | 2026-04-18 07:14:15 | MASTER-OAFA | (16h 16m 57.41s , -21d 45m 48.8s) | C | 60 | 19.5 | 119575 | 2026-04-18 09:34:26 | MASTER-OAGH | (16h 20m 52.34s , -22d 05m 17.1s) | C | 180 | 19.2 | 119575 | 2026-04-18 09:34:26 | MASTER-OAGH | (16h 22m 13.44s , -22d 38m 32.3s) | C | 180 | 19.2 | 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/44338. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42459] EP260417a/GRB 260417A: refined analysis of the EP-WXT and follow-up EP-FXT observations
by GCN Circulars 18 Apr '26

18 Apr '26

TITLE: GCN CIRCULAR NUMBER: 44337 SUBJECT: EP260417a/GRB 260417A: refined analysis of the EP-WXT and follow-up EP-FXT observations DATE: 26/04/18 08:34:24 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> K. R. Ni (CCNU), Y. L. Wang (NAO, CAS; ICE, CSIC), Y. Q. Zhao (USTC; PRIC) and Z. X. Ling (NAO, CAS) on behalf of the Einstein Probe (EP) team: The X-ray transient EP260417a was detected by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission (Wang et al., GCN 44325) at 2026-04-17 00:23:02 (UTC). The average WXT 0.5-4 keV spectrum can be fitted with an absorbed power law with a fixed Galactic hydrogen column density of 1.32 × 10^21 cm^-2, and a photon index of 0.78 (+/-0.27). The derived average unabsorbed 0.5-4 keV flux is 1.57 (+0.49/-0.39) × 10^(-10) erg/s/cm^2. Follow-up observation by the Follow-up X-ray Telescope (FXT) on board EP was performed at 2026-04-17T14:24:17 (UTC), ~14 hours after the WXT detection. The exposure time of the observation is around 3 ks. The on-ground analysis of the FXT data found an uncatalogued source at R.A. = 245.3232, DEC = -22.0249 (J2000) with an uncertainty of 10 arcsec (radius, 90% C.L. statistical and systematic). The FXT light curve shows no significant variability. The average FXT 0.5-10 keV spectra can be fitted with an absorbed power-law with a free hydrogen column density of 1.54 (+/-0.4) × 10^21 cm^-2, and a photon index of 1.68 (+/-0.13). The derived average unabsorbed 0.5-10 keV flux is 7.79 (-0.76/+0.89) × 10^(-12) erg/s/cm^2. The uncertainties are at the 90% confidence level for the above parameters. We note that the X-ray position determined from EP/FXT observation is ~6.6 degrees away from that of GRB 260417A, which is RA = 252.0, Dec = -19.8 (J2000) with a statistical uncertainty of 3.4 degrees, as reported by the Fermi GBM team (GCN 44317). The detection in X-rays by WXT was ~13 minutes later than the reported GBM detection time of GRB 260417A. Therefore it is possible that GRB 260417A is the Gamma-ray counterpart of EP260417a. 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/44337. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42458] EP260416a: NOT tentative spectroscopic redshift of z =1.909
by GCN Circulars 18 Apr '26

18 Apr '26

TITLE: GCN CIRCULAR NUMBER: 44336 SUBJECT: EP260416a: NOT tentative spectroscopic redshift of z =1.909 DATE: 26/04/18 05:02:56 GMT FROM: L. B. He at NAOC <helb(a)bao.ac.cn> L.B. He, X. Liu, Z.P. Zhu, S.Q. Jiang, J. An, D. Xu (NAOC), S.Y. Fu (HUST), J. P. U. Fynbo (DAWN/NBI), L. Fuglsang (NOT) report: We observed the optical counterpart (e.g., Ducoin et al., 44310) of EP260416a (Hu et al., GCN 44307) using the Nordic Optical Telescope (NOT), equipped with the ALFOSC camera and spectrograph. Observations started at 2026-04-17T03:56:49, and 2x1800 s spectra were obtained, covering the wavelength range 3800-9000 AA. The trace has quite low signal-to-noise. The continuum is throughout the wavelength range. We identify two relatively prominent absorption lines as Mg II doublet at z = 1.909. Based on it, other weak lines as due to Fe II 2600, Fe II 2374, 2383, Al II 1671 are consistent with this redshift. We tentatively conclude that this is the redshift of EP260416a. View this GCN Circular online at https://gcn.nasa.gov/circulars/44336. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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