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

[vsnet-grb-info 38372] GRB 250504A: Swift detection of a burst
by GCN Circulars 04 May '25

04 May '25

TITLE: GCN CIRCULAR NUMBER: 40343 SUBJECT: GRB 250504A: Swift detection of a burst DATE: 25/05/04 23:44:16 GMT FROM: David Palmer at LANL <palmer(a)lanl.gov> M. J. Moss (GSFC), C. Gronwall (PSU), R. Gupta (NASA GSFC), J. A. Kennea (PSU), D. M. Palmer (LANL) and M. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift Observatory Team: At 23:25:57 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 250504A (trigger=1310284). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 269.612, -40.349 which is RA(J2000) = 17h 58m 27s Dec(J2000) = -40d 20' 57" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a complex structure with a duration of about 60 sec. The peak count rate was ~4000 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 23:27:15.3 UT, 77.9 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source with an enhanced position: RA, Dec 269.61691, -40.36642 which is equivalent to: RA(J2000) = 17h 58m 28.06s Dec(J2000) = -40d 21' 59.1" with an uncertainty of 1.9 arcseconds (radius, 90% containment). This location is 64 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at https://www.swift.ac.uk/sper. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 2.12 x 10^21 cm^-2 (Willingale et al. 2013). UVOT took a finding chart exposure of 250 seconds with the U filter starting 137 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of the XRT error circle. Because of the density of catalogued stars, further analysis is required to report an upper limit for any afterglow in the sub-image. The 8'x8' region for the list of sources generated on-board covers 0.00% of the XRT error circle. No correction has been made for the expected extinction corresponding to E(B-V) of 0.191. Burst Advocate for this burst is M. J. Moss (mikejmoss3 AT gmail.com). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/) View this GCN Circular online at https://gcn.nasa.gov/circulars/40343. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 38371] GRB 250504A: Fermi GBM Final Real-time Localization
by GCN Circulars 04 May '25

04 May '25

TITLE: GCN CIRCULAR NUMBER: 40342 SUBJECT: GRB 250504A: Fermi GBM Final Real-time Localization DATE: 25/05/04 23:36:31 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 23:25:54 UT on 4 May 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250504A (trigger 768093959.78286 / 250504976). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 265.4, Dec = -40.9 (J2000 degrees, equivalent to J2000 17h 41m, -40d 53'), with a statistical uncertainty of 2.1 degrees. The angle from the Fermi LAT boresight is 113.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250504976/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250504976/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250504976/… View this GCN Circular online at https://gcn.nasa.gov/circulars/40342. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[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…

1 0

[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…

1 0

[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…

1 0

[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…

1 0

[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…

1 0

[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…

1 0

[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…

1 0

[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…

1 0

2025

2024

2023

2022

2021

vsnet-grb-info