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

[vsnet-grb-info 38630] Fermi GRB 250531A: Global MASTER-Net observations report
by GCN Circulars 31 May '25

31 May '25

TITLE: GCN CIRCULAR NUMBER: 40594 SUBJECT: Fermi GRB 250531A: Global MASTER-Net observations report DATE: 25/05/31 19:31:27 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.… [View More]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-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB 250531A ( Fermi GBM team, GCN 40593) errorbox 1696 sec after notice time and 1758 sec after trigger time at 2025-05-31 18:31:43 UT, with upper limit up to 19.5 mag. The observations began at zenith distance = 40 deg. The sun altitude is -35.3 deg. The galactic latitude b = 60 deg., longitude l = 256 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2887934 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 1789 | 2025-05-31 18:31:43 | MASTER-SAAO | (11h 22m 12.13s , +04d 56m 45.8s) | C | 60 | 19.5 | 1789 | 2025-05-31 18:31:43 | MASTER- | (11h 20m 21.93s , +05d 14m 38.0s) | C | 60 | 18.2 | 2577 | 2025-05-31 18:44:51 | MASTER-SAAO | (11h 30m 08.86s , +04d 56m 11.0s) | C | 60 | 19.3 | 2577 | 2025-05-31 18:44:51 | MASTER- | (11h 28m 19.20s , +05d 14m 00.4s) | C | 60 | 18.0 | 3202 | 2025-05-31 18:55:16 | MASTER-SAAO | (11h 22m 07.05s , +04d 58m 37.2s) | C | 60 | 19.5 | 3202 | 2025-05-31 18:55:16 | MASTER- | (11h 20m 17.21s , +05d 16m 27.2s) | C | 60 | 18.1 | 3797 | 2025-05-31 19:05:11 | MASTER-SAAO | (11h 30m 09.65s , +04d 57m 47.3s) | C | 60 | 19.3 | 3797 | 2025-05-31 19:05:11 | MASTER- | (11h 28m 19.98s , +05d 15m 38.0s) | C | 60 | 18.1 | 4208 | 2025-05-31 19:12:03 | MASTER-SAAO | (11h 22m 12.67s , +04d 57m 20.7s) | C | 60 | 19.4 | 4208 | 2025-05-31 19:12:03 | MASTER- | (11h 20m 22.82s , +05d 15m 08.3s) | C | 60 | 18.1 | 4404 | 2025-05-31 19:15:18 | MASTER-SAAO | (11h 30m 12.61s , +04d 57m 31.8s) | C | 60 | 19.3 | 4404 | 2025-05-31 19:15:18 | MASTER- | (11h 28m 22.60s , +05d 15m 21.9s) | C | 60 | 18.1 | 4501 | 2025-05-31 19:16:55 | MASTER-SAAO | (11h 20m 30.68s , +03d 04m 26.2s) | C | 60 | 19.4 | 4501 | 2025-05-31 19:16:55 | MASTER- | (11h 18m 41.05s , +03d 22m 16.5s) | C | 60 | 18.2 | 4594 | 2025-05-31 19:18:28 | MASTER-SAAO | (11h 28m 31.94s , +03d 05m 15.3s) | C | 60 | 19.4 | 4594 | 2025-05-31 19:18:28 | MASTER- | (11h 26m 42.18s , +03d 23m 06.9s) | C | 60 | 18.2 | 4688 | 2025-05-31 19:20:02 | MASTER-SAAO | (11h 24m 27.91s , +06d 51m 33.1s) | C | 60 | 19.4 | 4688 | 2025-05-31 19:20:02 | MASTER- | (11h 22m 37.83s , +07d 09m 23.1s) | C | 60 | 17.9 | 4783 | 2025-05-31 19:21:37 | MASTER-SAAO | (11h 32m 38.83s , +06d 51m 42.0s) | C | 60 | 19.2 | 4783 | 2025-05-31 19:21:37 | MASTER- | (11h 30m 48.71s , +07d 09m 32.8s) | C | 60 | 17.9 | 4877 | 2025-05-31 19:23:11 | MASTER-SAAO | (11h 22m 08.08s , +04d 59m 13.6s) | C | 60 | 19.5 | 4877 | 2025-05-31 19:23:11 | MASTER- | (11h 20m 18.35s , +05d 17m 04.3s) | C | 60 | 18.4 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. View this GCN Circular online at https://gcn.nasa.gov/circulars/40594. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L… [View Less]

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[vsnet-grb-info 38629] GRB 250531A: Fermi GBM Final Real-time Localization
by GCN Circulars 31 May '25

31 May '25

TITLE: GCN CIRCULAR NUMBER: 40593 SUBJECT: GRB 250531A: Fermi GBM Final Real-time Localization DATE: 25/05/31 18:12:52 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 18:02:24 UT on 31 May 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250531A (trigger 770407349.523472 / 250531752). The on-ground calculated location, using the Fermi GBM trigger data, is RA =… [View More]

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[vsnet-grb-info 38628] EP#01709177494: Swift-XRT counterpart detection of known source
by GCN Circulars 31 May '25

31 May '25

TITLE: GCN CIRCULAR NUMBER: 40592 SUBJECT: EP#01709177494: Swift-XRT counterpart detection of known source DATE: 25/05/31 17:47:34 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> P.A. Evans (U. Leicester), J.A. Kennea (PSU), E. Ambrosi (INAF-IASFPA) , A.P. Beardmore (U. Leicester), M.G. Bernardini (INAF-OAB), R. Brivio (INAF-OAB), D.N. Burrows (PSU), S. Campana (INAF-OAB), M. Capalbi (INAF-IASFPA), A. D'Ai (INAF-IASFPA), P. D'Avanzo (INAF-OAB), V. D'Elia (SSDC &… [View More]amp; INAF-OAR), S. Dichiara (PSU), M. Ferro (INAF-OAB), A. Melandri (INAF-OAR), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), M. Perri (SSDC & INAF-OAR), C. Salvaggio (INAF-OAB), T. Sbarrato (INAF-OAB), B. Sbarufatti (INAF-OAB), M.A. Williams (PSU) report on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of the Einstein Probe/WXT-detected source EP#01709177494, collecting 2.0 ks of Photon Counting (PC) mode data between T0+388 s and T0+6.2 ks after the trigger. A candidate counterpart has been found. The details of this source are: Source 1 (SWIFT J170930.3-263917): ================================== RA (J2000.0): 257.3766 = 17h 09m 30.38s Dec (J2000.0): -26.6548 = -26d 39' 17.3" Error: 3.5 (arcsec, radius, 90% confidence). Detect flag: GOOD Distance: 20 arcsec from the Einstein Probe/WXT position. Mean rate: 11.35 +/- 0.22 ct s^-1 Mean flux: (4.665 +/- 0.088)e-10 erg cm^-2 s^-1 Peak rate: 18.7 +/- 3.1 ct s^-1 Peak flux: (7.7 +/- 1.3)e-10 erg cm^-2 s^-1 ECF: 4.11e-11 erg cm^-2 ct^-1, assuming NH=4.40e+21 cm^-2, gamma=1.98; determined from a spectral fit. This matches a catalogued X-ray source LSXPS J170930.1-263918 in the LSXPS catalogue. Details: Separation: 3.2" from the XRT source Cat Rate: 1.2e+00 +/- 9.0e-03 ct s^-1 Cat Flux: 4.7e-11 +/- 3.7e-13 erg cm^-2 s^-1 (0.3-10 keV) so the source is 5.7-sigma above the catalogued flux. There is no evidence for fading. A SIMBAD object `RX J1709.5-2639' is 8.3" away. There is 1 2MASS object within the source's 3-sigma error radius. All fluxes are 0.3-10 keV, observed. For all flux conversions and comparisons with catalogues and upper limits from other missions, we assumed a power-law spectrum with NH=3x10^20 cm^-2 and photon index (Gamma)=1.7 unless otherwise stated. The results of the XRT-team automatic analysis of the XRT observations, including a position-specific upper limit calculator, are available at https://www.swift.ac.uk/EP. This circular is an officicial product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/40592. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L… [View Less]

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[vsnet-grb-info 38627] EP#01709177494: Swift-XRT counterpart detection of known source
by GCN Circulars 31 May '25

31 May '25

TITLE: GCN CIRCULAR NUMBER: 40592 SUBJECT: EP#01709177494: Swift-XRT counterpart detection of known source DATE: 25/05/31 17:47:34 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> P.A. Evans (U. Leicester), J.A. Kennea (PSU), E. Ambrosi (INAF-IASFPA) , A.P. Beardmore (U. Leicester), M.G. Bernardini (INAF-OAB), R. Brivio (INAF-OAB), D.N. Burrows (PSU), S. Campana (INAF-OAB), M. Capalbi (INAF-IASFPA), A. D'Ai (INAF-IASFPA), P. D'Avanzo (INAF-OAB), V. D'Elia (SSDC &… [View More]amp; INAF-OAR), S. Dichiara (PSU), M. Ferro (INAF-OAB), A. Melandri (INAF-OAR), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), M. Perri (SSDC & INAF-OAR), C. Salvaggio (INAF-OAB), T. Sbarrato (INAF-OAB), B. Sbarufatti (INAF-OAB), M.A. Williams (PSU) report on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of the Einstein Probe/WXT-detected source EP#01709177494, collecting 2.0 ks of Photon Counting (PC) mode data between T0+388 s and T0+6.2 ks after the trigger. A candidate counterpart has been found. The details of this source are: Source 1 (SWIFT J170930.3-263917): ================================== RA (J2000.0): 257.3766 = 17h 09m 30.38s Dec (J2000.0): -26.6548 = -26d 39' 17.3" Error: 3.5 (arcsec, radius, 90% confidence). Detect flag: GOOD Distance: 20 arcsec from the Einstein Probe/WXT position. Mean rate: 11.35 +/- 0.22 ct s^-1 Mean flux: (4.665 +/- 0.088)e-10 erg cm^-2 s^-1 Peak rate: 18.7 +/- 3.1 ct s^-1 Peak flux: (7.7 +/- 1.3)e-10 erg cm^-2 s^-1 ECF: 4.11e-11 erg cm^-2 ct^-1, assuming NH=4.40e+21 cm^-2, gamma=1.98; determined from a spectral fit. This matches a catalogued X-ray source LSXPS J170930.1-263918 in the LSXPS catalogue. Details: Separation: 3.2" from the XRT source Cat Rate: 1.2e+00 +/- 9.0e-03 ct s^-1 Cat Flux: 4.7e-11 +/- 3.7e-13 erg cm^-2 s^-1 (0.3-10 keV) so the source is 5.7-sigma above the catalogued flux. There is no evidence for fading. A SIMBAD object `RX J1709.5-2639' is 8.3" away. There is 1 2MASS object within the source's 3-sigma error radius. All fluxes are 0.3-10 keV, observed. For all flux conversions and comparisons with catalogues and upper limits from other missions, we assumed a power-law spectrum with NH=3x10^20 cm^-2 and photon index (Gamma)=1.7 unless otherwise stated. The results of the XRT-team automatic analysis of the XRT observations, including a position-specific upper limit calculator, are available at https://www.swift.ac.uk/EP. This circular is an officicial product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/40592. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L… [View Less]

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[vsnet-grb-info 38626] GRB 250530C: BOOTES-7 optical upper limit
by GCN Circulars 31 May '25

31 May '25

TITLE: GCN CIRCULAR NUMBER: 40591 SUBJECT: GRB 250530C: BOOTES-7 optical upper limit DATE: 25/05/31 17:31:45 GMT FROM: I. Perez-Garcia at Institute of Astrophysics of Andalusia <ipg(a)iaa.es> I. Perez-Garcia, E. Fernandez-Garcia, S.-Y. Wu, M. D. Caballero-Garcia, R. Sanchez-Ramirez, S. Guziy, and A. J. Castro-Tirado (IAA-CSIC, Granada), C. Perez del Pulgar (Univ. of Malaga), L. Hernandez-Garcia (Univ. of Valparaiso), M. Gritsevich (Univ. of Helsinki), Y.-D. Hu (GXU), B.-B. Zhang … [View More]

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[vsnet-grb-info 38625] GRB 250521C/ZTF25aarhkyn/AT2025mgj: COLIBRÍ optical observations
by GCN Circulars 31 May '25

31 May '25

TITLE: GCN CIRCULAR NUMBER: 40590 SUBJECT: GRB 250521C/ZTF25aarhkyn/AT2025mgj: COLIBRÍ optical observations DATE: 25/05/31 15:39:50 GMT FROM: Rosa L. Becerra at Tor Vergata, Roma <rosa.becerra(a)roma2.infn.it> Rosa L. Becerra (U Roma), Alan M. Watson (UNAM), Francis Fortin (IRAP), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Jean-Luc Atteia (IRAP), Fredd Alvarez (UNAM), Dalya Akl (AUS), Camila Angulo (UNAM), Sarah Antier (OCA), Nathaniel R. Butler (ASU) , Damien Dornic (… [View More]CPPM), Jean-Grégoire Ducoin (CPPM), Leonardo García García (UNAM), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Kin Ocelotl López (UNAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Benjamin Schneider (LAM) and Antonio de Ugarte Postigo (LAM): We imaged the field of ZTF25aarhkyn/AT2025mgj (Andreoni et al., GCN Circ. 40566) using the DDRAGO wide-field imager on the COLIBRÍ telescope. We observed from 2025-05-31 03:33 to 04:32 UTC, after 9.6 days after the trigger of GRB 250521C (Fermi GBM team, GCN 40515) and obtained 16 minutes of exposure in each of the g, r and i filters. The data were reduced and stacked using the COLIBRÍ 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 detected the candidate ZTF25aarhkyn/AT2025mgj (Andreoni et al., GCN Circ. 40566), at preliminary magnitudes of: g = 19.34 +/- 0.03 r = 19.46 +/- 0.03 i = 19.50 +/- 0.05 Compared with the NOT observations reported by Martin-Carrillo et al. (GCN Circ. 40584), we estimate a steeper temporal decay index of ~1.5. The measured colours are consistent with those typically observed in GRBs, suggesting a similar nature. Additionally, the temporal evolution may indicate that AT2025mgj is a possible off-axis GRB; however, the absence of a nearby galaxy makes this scenario unlikely. Further observations are planned in order to unravel the nature of this object. 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/40590. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L… [View Less]

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[vsnet-grb-info 38624] GRB 250530C: Swift-XRT refined Analysis
by GCN Circulars 31 May '25

31 May '25

TITLE: GCN CIRCULAR NUMBER: 40589 SUBJECT: GRB 250530C: Swift-XRT refined Analysis DATE: 25/05/31 11:31:46 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> M.A. Williams (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), M. Ferro (INAF-OAB), R. Brivio (INAF-OAB), A. D'Ai (INAF-IASFPA), S. Dichiara (PSU), J.A. Kennea (PSU) and P.A. Evans report on behalf of the Swift-XRT team: We have analysed 7.7 ks of XRT data for GRB … [View More]

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[vsnet-grb-info 38623] GRB 250530A: TNG detection of a NIR source inside the Swift/XRT error circle
by GCN Circulars 31 May '25

31 May '25

TITLE: GCN CIRCULAR NUMBER: 40588 SUBJECT: GRB 250530A: TNG detection of a NIR source inside the Swift/XRT error circle DATE: 25/05/31 09:10:56 GMT FROM: Paolo D'Avanzo at INAF - OAB <paolo.davanzo(a)inaf.it> P. D'Avanzo, (INAF-OAB), A. Melandri (INAF-OAR), L. Izzo (INAF - OACn), M. G. Bernardini (INAF-OAB & LUPM), R. Brivio, M. Ferro (INAF-OAB), M. Pedani (INAF-TNG) on behalf of the CIBO collaboration report: We observed the field of the GRB 250530A detected by SVOM (Wang … [View More]

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[vsnet-grb-info 38622] Swift GRB 250530C: Global MASTER-Net observations report
by GCN Circulars 31 May '25

31 May '25

TITLE: GCN CIRCULAR NUMBER: 40587 SUBJECT: Swift GRB 250530C: Global MASTER-Net observations report DATE: 25/05/31 04:17:20 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.… [View More]

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[vsnet-grb-info 38621] GRB 250530C: Enhanced Swift-XRT position
by GCN Circulars 31 May '25

31 May '25

TITLE: GCN CIRCULAR NUMBER: 40586 SUBJECT: GRB 250530C: Enhanced Swift-XRT position DATE: 25/05/31 00:38:35 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team. Using 2203 s of XRT Photon Counting mode data and 5 UVOT images for GRB 250530C, we find an astrometrically corrected X-ray position (using the XRT-UVOT alignment and matching UVOT field sources to the … [View More]

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