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

[vsnet-grb-info 38370] Swift GRB250504.98: Global MASTER-Net observations report
by GCN Circulars 04 May '25

04 May '25

TITLE: GCN CIRCULAR NUMBER: 40341 SUBJECT: Swift GRB250504.98: Global MASTER-Net observations report DATE: 25/05/04 23:35:52 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-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) was pointed to the Swift GRB250504.98 (trigger No 1310284,17h 58m 26.88s , -40d 20m 56.4s, R=0.05) errorbox 14 sec after notice time and 40 sec after trigger time at 2025-05-04 23:26:38 UT, with upper limit up to 16.7 mag. The observations began at zenith distance = 29 deg. The sun altitude is -70.3 deg. The galactic latitude b = -9 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=2860822 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 46 | MASTER-SAAO | C | 10 | 16.7 | 75 | MASTER-SAAO | C | 10 | 16.7 | 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/40341. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38369] GRB 250502A: Swift/UVOT Follow up
by GCN Circulars 04 May '25

04 May '25

TITLE: GCN CIRCULAR NUMBER: 40340 SUBJECT: GRB 250502A: Swift/UVOT Follow up DATE: 25/05/04 20:03:01 GMT FROM: Paul Kuin at MSSL <npkuin(a)gmail.com> Paul Kuin (MSSL/UCL) reports on behalf of the Swift/UVOT team: The Swift/UVOT began observations of the field of SVOM detected GRB 250502A 72ks after the SVOM ECLAIR trigger (Wang et al., GCN Circ. 40313). A source consistent with the position reported by Ny Avo Rakotondraine et al. (GCN Circ. 40315) has been detected in the initial UVOT exposures. The detections using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: Filter T_start T_stop Exp(s) Mag (Vega) Wh 78ks 95ks 880 21.5+/- 0.35 u 72ks 106ks 3664 >21.3 (3-sigma UL) View this GCN Circular online at https://gcn.nasa.gov/circulars/40340. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38368] GRB 250502A: Mondy and Tien-Shan Optical Observations
by GCN Circulars 04 May '25

04 May '25

TITLE: GCN CIRCULAR NUMBER: 40339 SUBJECT: GRB 250502A: Mondy and Tien-Shan Optical Observations DATE: 25/05/04 11:59:20 GMT FROM: Nicolai Pankov at HSE, IKI RAS <colinsergesen(a)gmail.com> N. Pankov (HSE, IKI), E. Klunko (ISTP), I. Reva (FAI), A. Pozanenko (IKI) report on behalf of IKI-GRB-FuN: We performed follow-up observations of the optical counterpart (Rakotondrainibe et. al, GCN 40315) to GRB 250502A (Wang et al., GCN 40313) using the 1.5-meter AZT-33IK telescope of the Sayan Solar Observatory (Mondy), and the 1-meter Zeiss-1000 telescope of the Tien-Shan Astronomical Observatory (TSHAO). The optical source was observed also by (An et. al, GCN 40319; Li et. al, GCN 40320; Ghosh et. al, GCN 40322; Ugarte Postigo et. al, GCN 40328; Pérez-Fournon et. al, GCN 40330; Odeh et. al, GCN 40331; Bochenek & Perley, GCN 40333; Corcoran et. al, GCN 40334; Leonini et. al, GCN 40337; Zheng et. al, GCN 40338). The redshift z = 2.163 was determined by Ugarte Postigo et. al, GCN 40328. The X-Ray counterpart was detected by XRT (Dichiara et. al, GCN 40336). Our observations began on 02.05.2025 (UT) 15:48 at Mondy Observatory and 2025-05-03 18:25:43 at Tien-Shan Observatory. We detect the optical counterpart in the stacked image in the first observation. The preliminary photometry is as follows: Date UTstart Exptime t-T0 Filter OT Err UL (s) (mid, days) (3sigma) 2025-05-02 15:48:58 30*120 0.31425 R 19.74 0.10 22.5 2025-05-03 18:25:43 20*120 1.41617 R n/d n/d 21.0 The photometry is based on nearby USNO-B1.0 stars and has not been corrected for the Galactic extinction. Reference stars RA Dec R2 206.5862 -10.7663 14.69 206.4706 -10.7622 16.20 206.5453 -10.7644 17.95 View this GCN Circular online at https://gcn.nasa.gov/circulars/40339. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38367] GRB 250502A: KAIT optical observations
by GCN Circulars 04 May '25

04 May '25

TITLE: GCN CIRCULAR NUMBER: 40338 SUBJECT: GRB 250502A: KAIT optical observations DATE: 25/05/04 08:20:51 GMT FROM: Weikang Zheng at UC Berkeley <weikang(a)berkeley.edu> WeiKang Zheng (UCB), Xuhui Han (NAOC), Pinpin Zhang (NAOC) and Alexei V. Filippenko (UCB) report on behalf of the KAIT GRB team: The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at Lick Observatory, observed the field of SVOM GRB 250502A (Wang et al., GCN 40313) starting at 08:58, May 02 UT, about 12 minutes after the burst. Observations were performed in 3 x 3 tiling mode, a set of clear (roughly R) filter images were obtained. We detected the optical afterglow (Rakotondrainibe et al., GCN 40315; An et al., GCN 40319; Li et al., GCN 40320; Gosh et al., GCN 40322; de Ugarte Postigo et al., GCN 40328; Perez-Fournon et al., GCN 40330; Odeh & Guessoum, GCN 40331; Bochenek & Perley, GCN 40333; Corcoran et al., GCN 40334 and Leonini et al., GCN 40337), which decayed from 17.4 +/- 0.1 mag (Vega) at 963s to 18.7 +/- 0.2 mag at 7.6ks after the burst. View this GCN Circular online at https://gcn.nasa.gov/circulars/40338. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38366] GRB 250502A: Montarrenti Observatory optical detection
by GCN Circulars 03 May '25

03 May '25

TITLE: GCN CIRCULAR NUMBER: 40337 SUBJECT: GRB 250502A: Montarrenti Observatory optical detection DATE: 25/05/03 21:54:31 GMT FROM: Simone Leonini at Montarrenti Observatory (Siena, Italy) <s.leonini(a)iol.it> S. Leonini, M. Conti, P. Rosi, L.M. Tinjaca Ramirez (Montarrenti Observatory, Siena, Italy, part of UAI/SSV-GRB section), M.G. Dainotti (National Astronomical Observatory of Japan), Y. Niino (Tokyo University, Institute of Astronomy) and K. Kalinowski (Aarhus University, Department of Physics and Astronomy) report: we observed the field of GRB 250502A detected by SVOM/ECLAIRs (Wang et al., GCN 40313) with the automated and remoted 0.53m Ritchey-Chretien telescope at Montarrenti Observatory (Siena, Italy, IAU code C88). The observations were started at 2025-05-02 20:42:17 UT (approximately 12 hours after burst) stacking a set of Rc-band CCD images. Observations were performed under thin cloud cover in the second part of the night. The optical afterglow (Rakotondrainibe et al., GCN 40315; An et al., GCN 40319; Li et al., GCN 40320; Gosh et al., GCN 40322; de Ugarte Postigo et al. with a redshift of z = 2.163, GCN 40328 ; Perez-Fournon et al., GCN 40330; Odeh & Guessoum, GCN 40331; Bochenek & Perley, GCN 40333; Corcoran et al., GCN 40334 and Dichiara et al., GCN 40336) was barely detected (S/N =2.1) at the following position: RA (J2000.0) 13h 46m 05.60s +/-0.23 Decl. (J2000.0) -10° 45' 31.70" +/-0.16 Preliminary photometry was obtained using nearby PanSTARRS stars as follows: Observation Mid-Time T-T0 (hr) Exposure Filter Mag. Err. 2025-05-02 21:31:19 UT 12.75 140x40s Rc 20.70 +/- 0.15 Magnitude was calibrated with the nearby PanSTARRS stars converted using Lupton (2005) equations. No correction for galactic dust extinction was applied. View this GCN Circular online at https://gcn.nasa.gov/circulars/40337. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38365] GRB 250502A: Swift-XRT afterglow detection
by GCN Circulars 03 May '25

03 May '25

TITLE: GCN CIRCULAR NUMBER: 40336 SUBJECT: GRB 250502A: Swift-XRT afterglow detection DATE: 25/05/03 19:00:30 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> S. Dichiara (PSU), J.A. Kennea (PSU), D.N. Burrows (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAR), T. Sbarrato (INAF-OAB) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of the SVOM/ECLAIRs-detected burst GRB 250502A (GCN 40313). We searched for X-ray sources in 4.6 ks of Photon Counting (PC) mode data. The total exposure at the position of the afterglow (see below) is 4.6 ks, obtained between T0+72.1 ks and T0+105.5 ks. An uncatalogued X-ray source is detected consistent with the SVOM/COLIBRI error region (GCN 40315) and is believed to be the afterglow. Using 2113 s of PC mode data and 2 UVOT images, we find an enhanced XRT position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 206.52396, -10.75879 which is equivalent to: RA (J2000): 13h 46m 05.75s Dec(J2000): -10d 45' 31.6" with an uncertainty of 4.5 arcsec (radius, 90% confidence). This position is 2.3 arcsec from the SVOM/COLIBRI position. The source has a mean count rate of 1.3e-02 ct/sec; we cannot determine at the present time whether it is fading. However, given the coincidence in position with the optical counterpart (GCNs 40315, 40319, 40320, 40322, 40330, 40331, 40333, 40334) at a redshift of 2.163 (GCN 40328), we confirm this as the X-ray afterglow. A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.4 (+1.6, -0.7). The best-fitting absorption column is consistent with the Galactic value of 5.0 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.1 x 10^-11 (3.6 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 5 (+/-31) x 10^20 cm^-2 Galactic foreground: 5.0 x 10^20 cm^-2 Excess significance: <1.6 sigma Photon index: 2.4 (+1.6, -0.7) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00021827. The results of the full analysis of the XRT observations are available at https://www.swift.ac.uk/ToO_GRBs/00021827. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/40336. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38364] Fermi trigger No 767975731: Global MASTER-Net observations report
by GCN Circulars 03 May '25

03 May '25

TITLE: GCN CIRCULAR NUMBER: 40335 SUBJECT: Fermi trigger No 767975731: Global MASTER-Net observations report DATE: 25/05/03 17:18:05 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-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 GRB250503.61 (trigger No 767975731,03h 36m 12.00s , +19d 13m 58.8s, R=29.12) errorbox 8992 sec after notice time and 9028 sec after trigger time at 2025-05-03 17:05:54 UT, with upper limit up to 17.2 mag. Observations started at twilight. The observations began at zenith distance = 73 deg. The sun altitude is -14.6 deg. The galactic latitude b = -28 deg., longitude l = 169 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2859360 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 9058 | 2025-05-03 17:05:54 | MASTER-SAAO | (05h 25m 27.01s , +16d 50m 49.7s) | C | 60 | 17.2 | 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/40335. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38363] GRB 250502A: NOT optical observations
by GCN Circulars 03 May '25

03 May '25

TITLE: GCN CIRCULAR NUMBER: 40334 SUBJECT: GRB 250502A: NOT optical observations DATE: 25/05/03 12:59:00 GMT FROM: Gregory Corcoran at University College Dublin <gregory.corcoran(a)ucdconnect.ie> G. Corcoran (UCD), D. B. Malesani (DAWN/NBI and Radboud Univ.), A. Martin-Carrillo (UCD), A. de Ugarte Postigo (LAM), D. Xu (NAOC), A. Saccardi (CEA/Irfu), N. Pyykkinen (NOT and Turku), report on behalf of a larger collaboration: We observed the field of GRB 250502A detected by SVOM/ECLAIRs (Wang et al., GCN 40313), using the ALFOSC camera mounted on the Nordic Optical Telescope (NOT). We obtained exposures in the SDSS g, r, i (3x300 s each) and z (5x200 s) bands, starting at 21:41:17 UT on 2025-05-02 (12.914 hr after the SVOM/ECLAIRs trigger). The optical counterpart reported by Rakotondrainibe et al. (GCN 40315), An et al. (GCN 40319), Li et al. (GCN 40320), Ghosh et al. (GCN 40322), de Ugarte Postigo et al. (GCN 40328), Pérez-Fournon et al. (GCN 40330), Odeh & Guessoum (GCN 40331), Bochenek & Perley (GCN 40333) with a redshift of z = 2.163 (de Ugarte Postigo et al., GCN 40328) is well detected in all our frames. We measure the following preliminary magnitude (mid time 13.23 hr after the trigger): r = 20.71 +/- 0.03 (AB). The photometric calibration was performed using nearby stars from the Pan-STARRS catalog and the magnitudes are not corrected for Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/40334. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38362] GRB 250502a: Liverpool Telescope optical follow-up
by GCN Circulars 03 May '25

03 May '25

TITLE: GCN CIRCULAR NUMBER: 40333 SUBJECT: GRB 250502a: Liverpool Telescope optical follow-up DATE: 25/05/03 11:37:18 GMT FROM: A. Bochenek at Liverpool John Moores University <a.m.bochenek(a)2023.ljmu.ac.uk> A. Bochenek and D. A. Perley (LJMU) report: We observed the SVOM-detected GRB250502a (Wang et al., GCN 40313) using the IO:O optical camera on the 2m robotic Liverpool Telescope. We obtained 6x100s exposures in the SDSS r’ filter starting at 2025-05-02 23:54:39 UT, approximately 15.28 hours after the trigger. The first exposure had to be discarded, due to a tracking error. We report a detection in the stacked image at the position of the optical counterpart (Rakotondrainibe et al., GCN 40315; An et al., GCN 40319). The magnitude of the afterglow is r = 21.04 ± 0.05, which is in agreement with observations by de Ugarte Postigo et al. (GCN 40328) and Pérez-Fournon et al. (GCN 40330). The photometry was calibrated using nearby PanSTARRS secondary standards and was not corrected for extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/40333. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38361] GRB 250502B: AstroSat CZTI detection
by GCN Circulars 03 May '25

03 May '25

TITLE: GCN CIRCULAR NUMBER: 40332 SUBJECT: GRB 250502B: AstroSat CZTI detection DATE: 25/05/03 09:01:01 GMT FROM: Gaurav Waratkar at IIT Bombay <gauravwaratkar(a)iitb.ac.in> M. Tembhurnikar (IUCAA), G. Waratkar (IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration: Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a long duration GRB 250502B which was also detected by Fermi/GBM (Fermi GBM Team, GCN Circ. 40314). The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2025-05-02 10:13:59 UTC. The measured peak count rate associated with the burst is 73 (+34, -4) counts/s above the background in the combined data of two quadrants (out of four), with a total of 379 (+260, -70) counts. The local mean background count rate was 141 (+1, -4) counts/s. Using cumulative rates, we measure a T90 of 17 (+4, -12) s. The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2025-05-02 10:13:52 UTC. The measured peak count rate associated with the burst is 158 (+75, -9) counts/s above the background in the combined data of all quadrants, with a total of 1160 (+408, -455) counts. The local mean background count rate was 1232 (+6, -6) counts/s. We measure a T90 of 18 (+3, -9) s from the cumulative Veto light curve. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project. CZTI GRB detections are reported regularly on the payload site at: http://astrosat.iucaa.in/czti/?q=grb View this GCN Circular online at https://gcn.nasa.gov/circulars/40332. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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