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

[vsnet-grb-info 37788] GRB 250317B: Mondy AZT-33IK Optical Observations
by GCN Circulars 18 Mar '25

18 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39772 SUBJECT: GRB 250317B: Mondy AZT-33IK Optical Observations DATE: 25/03/18 15:19:56 GMT FROM: Nicolai Pankov at HSE, IKI RAS <colinsergesen(a)gmail.com> N. Pankov (HSE, IKI), E. Klunko (ISTP), A. Pozanenko (IKI) report on behalf of IKI-GRB-FuN: We performed optical observations of the field of GRB 250317B (Zhao et. al, GCN 39753; Götz et. al, GCN 39756; Melandri et. al, GCN 39763) in the R filter with the 1.5-meter AZT-33IK telescope of the Sayan Solar Observatory (Mondy). The observations started on (UT) 2025-03-17 15:41:49, i.e. about 0.58 days since trigger. The optical afterglow (Watson et. al, GCN 39754; Pérez-Fournon et. al, GCN 39757; Ghosh et. al, GCN 39759; Ferro et. al, GCN 39764; Schneider et. al, GCN 39767; Zhu et. al, GCN 39770) is clearly visible in the stacked image. The preliminary photometry is as follows: Date UT start t-T0 Exp. Filter OT Err UL(3sigma) (mid, days) (s) 2025-03-17 15:41:49 0.58173 28*120 R 20.94 0.06 23.3 The photometry is based on nearby stars from the USNO-B1.0 catalog (R2 magnitudes) and has not been corrected for the Galactic extinction. Using a simple power law fit to the observed data in the r and R filters, we estimate the light curve decay index to be about -1.5. View this GCN Circular online at https://gcn.nasa.gov/circulars/39772. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37787] GRB 250317C: AstroSat CZTI detection
by GCN Circulars 18 Mar '25

18 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39771 SUBJECT: GRB 250317C: AstroSat CZTI detection DATE: 25/03/18 15:13:24 GMT FROM: Gaurav Waratkar at IIT Bombay <gauravwaratkar(a)iitb.ac.in> S. Salunke (IUCAA), 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 250317C which was also detected by GECAM-C (Wang et al., GCN Circ. 39768). The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2025-03-17 17:31:23.50 UTC. The measured peak count rate associated with the burst is 87 (+34, -21) counts/s above the background in the combined data of three quadrants (out of four), with a total of 356 (+153, -114) counts. The local mean background count rate was 278 (+3, -5) counts/s. Using cumulative rates, we measure a T90 of 8.1 (+1.62, -3.35) s. The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2025-03-17 17:31:25.21 UTC. The measured peak count rate associated with the burst is 225 (+62, -64) counts/s above the background in the combined data of all quadrants, with a total of 770 (+299, -346) counts. The local mean background count rate was 1266 (+9, -9) counts/s. We measure a T90 of 8.29 (+1.8, -4.7) 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/39771. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37786] GRB 250317B: NOT optical observations suggest an optical plateau phase
by GCN Circulars 18 Mar '25

18 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39770 SUBJECT: GRB 250317B: NOT optical observations suggest an optical plateau phase DATE: 25/03/18 13:35:17 GMT FROM: Antonio Martin-Carrillo at UCD,Space Science Group <antonio.martin-carrillo(a)ucd.ie> Z. P. Zhu (NAOC), D. B. Malesani (DAWN/NBI and Radboud Univ.), B. Schneider (LAM), A. Martin-Carrillo (UCD), A. Henderson de la Fuente (NOT), report on behalf of a larger collaboration: We observed the field of the GRB 250317B (Zhao et al., GCN 39753) using the ALFOSC camera mounted on the Nordic Optical Telescope (NOT). We obtained 2 exposures of 300 s each in the SDSS-r band starting at 22:43:24 UT on 2025-03-17 (20.56 hr after the trigger). The optical counterpart reported by Watson et al. (GCN 39754), Palmerio et al. (GCN 39755), Pérez-Fournon et al. (GCN 39757), Ghosh et al. (GCN 39759), Ferro et al. (GCN 39764) and Schneider et al. (GCN 39767) is well detected in the stacked image, with a preliminary magnitude of r = 21.7 +/- 0.1 mag (AB). The photometric calibration was performed using nearby stars from the Pan-STARRS catalog and the magnitude is not corrected for Galactic extinction. We note that the measured magnitude is consistent with those reported by Schneider et al. (GCN 39767), obtained ~1 hr before our observation, and Thoene et al. (GCN 39769), obtained about 0.6 hr after our observation, suggesting a possible optical plateau or rebrightening episode. Further observations are planned and encouraged to monitor the evolution of the optical afterglow. View this GCN Circular online at https://gcn.nasa.gov/circulars/39770. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37785] GRB 250317B: GTC/OSIRIS+ spectroscopic redshift z=3.44
by GCN Circulars 18 Mar '25

18 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39769 SUBJECT: GRB 250317B: GTC/OSIRIS+ spectroscopic redshift z=3.44 DATE: 25/03/18 12:43:40 GMT FROM: Christina Thöne at ASU-CAS <christina.thoene(a)gmail.com> C. C. Thoene (AbAO), A. de Ugarte Postigo (LAM), D. B. Malesani (DAWN/NBI and Radboud Univ.), J. F. Agui Fernandez (CAHA), N. A. Rakotondrainibe (LAM), A. Martin-Carrillo (UCD), N. R. Tanvir (Univ. Leicester), L. Izzo (INAF/OACn and DARK/NBI), J. P. U. Fynbo (DAWN/NBI), S. Geier (GTC), G. Lombardi (GTC), Antonio García (GTC), Daniel González (GTC), and Antonio Cabrera-Lavers (GTC) report: We obtained spectroscopy of the afterglow of the SVOM-detected GRB 250317B (Zhao et al. GCN 39752, Watson et al. GCN 39754, Götz et al. GCN 39756, Pérez-Fournon et al. GCN 39757, Melandri et al. GCN 39763, Ferro et al. GCN 39764, Schneider et al. GCN 39767). Our observations consisted of 4x1200s exposures with grism R1000B, covering the range between 3600 and 7880 AA with a resolving power of around 600 at a mean epoch 2025-03-18T00:16:22 UT (22.07 hr after the burst). In the acquisition image, obtained 21.328 hr after the burst, the afterglow is detected at a magnitude of r_AB=21.72 +/- 0.05, indicating a slight rebrightening with respect to the OHP observation (Schneider et al. GCN 39767) obtained 1.6 hr earlier. Further monitoring of this behaviour is encouraged. The spectrum shows continuum above 4000 AA, with features consistent with at least two low-column density Lyman systems at redshifts of z=3.442 and 3.447 (or a dynamic separation of 1500 km/s), likely corresponding to the same galaxy or system. There are tentative detections of SiII, SiII*, OI, SiIV, CIV, FeII and AlII a those same redshifts, which we identify as corresponding to the GRB. Additionally, we identify two intervening absorbers, one at z=3.196 with absorptions in several Lyman lines, SII and SiII, and a second one at z=1.029 showing the MgII doublet. View this GCN Circular online at https://gcn.nasa.gov/circulars/39769. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37784] GRB 250317C: GECAM-B detection
by GCN Circulars 18 Mar '25

18 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39768 SUBJECT: GRB 250317C: GECAM-B detection DATE: 25/03/18 11:31:10 GMT FROM: Yue Wang <m18509381757(a)163.com> Yue Wang, Shao-Lin Xiong, Chen-Wei Wang report on behalf of the GECAM team: GECAM-B was triggered both in-flight and on-ground by a long burst, GRB 250317C, at 2025-03-17T17:31:21.700 UTC (T0). According to the event-by-event data, the GECAM-B light curve shows a main pulse with a with a T90 of 23.0 +3.0/-4.0 s in the 40-6000 keV band. The GECAM-B light curve could be found here: https://www.bursthub.cn//admin/static/gecamgrb250317C.png Using the automatic on-ground localization pipeline, GECAM-B localized this burst to the following position (J2000): Ra: 320.42 deg Dec: -16.07 deg Err: 8.59 deg (1-sigma, statistical only) We note that these results are preliminary. Refined analysis will be reported later. Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor(GECAM) mission originally consists of two microsatellites (GECAM-A and GECAM-B) launched in Dec. 2020. As the third member of GECAM constellation, GECAM-C was launched onboard SATech-01 experimental satellite in July 2022. GECAM mission is funded by the Chinese Academy of Sciences (CAS). View this GCN Circular online at https://gcn.nasa.gov/circulars/39768. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37783] GRB 250317B: OHP/T193 optical observations
by GCN Circulars 17 Mar '25

17 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39767 SUBJECT: GRB 250317B: OHP/T193 optical observations DATE: 25/03/17 23:30:24 GMT FROM: Benjamin Schneider at MIT <bschn(a)mit.edu> B. Schneider (LAM), C. Adami (LAM/Pytheas/AMU), E. Le Floc'h (CEA/Irfu), A. Ugarte Postigo (LAM), M. Dennefeld (IAP/CNRS/Sorbonne U.) and D. Turpin (CEA/Irfu) report on behalf of a larger collaboration: We observed the field of the GRB 250317B (Zhao et al., GCN 39753) using the T193cm telescope at the Observatoire de Haute-Provence (France) equipped with the MISTRAL spectro-imager. We obtained 9 exposures (8x360 s and 1x300 s) in the r-band starting at 21:56:41 UT on 2025-03-17 (19.74 hours after the trigger). In the stacked image, we clearly detected the optical counterpart reported by Watson et al., GCN 39754; Palmerio et al., GCN 39755; Pérez-Fournon et al., GCN 39757; Ghosh et al., GCN 39759 and Ferro et al., GCN 39764. The preliminary magnitude derived for that source is: r = 21.87 +/- 0.08 mag (AB) The photometric calibration was performed using nearby stars from the PanSTARRS catalog and the magnitudes are not corrected for Galactic extinction. We acknowledge the excellent support from the Observatoire de Haute-Provence and in particular Jean Balcaen et Andres Carmona for the MISTRAL observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/39767. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37782] Fermi trigger No 763933627: Global MASTER-Net observations report
by GCN Circulars 17 Mar '25

17 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39766 SUBJECT: Fermi trigger No 763933627: Global MASTER-Net observations report DATE: 25/03/17 23:02:10 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, N.Tiurina, P.Balanutsa, , D.Vlasenko, I.Panchenko, A.Kuznetsov, G.Antipov, A.Sankovich, A.Sosnovskij, Yu.Tselik, M.Gulyaev, 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. 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 GRB250317.82 (trigger No 763933627,04h 54m 02.40s , -35d 41m 24.0s, R=1.38) errorbox 18 sec after notice time and 9688 sec after trigger time at 2025-03-17 22:28:31 UT, with upper limit up to 18.0 mag. The observations began at zenith distance = 79 deg. The sun altitude is -56.6 deg. The galactic latitude b = -38 deg., longitude l = 238 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2814784 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 9718 | 2025-03-17 22:28:31 | MASTER-SAAO | (04h 53m 49.54s , -35d 43m 51.2s) | C | 60 | 17.4 | 9778 | 2025-03-17 22:28:31 | MASTER-SAAO | (04h 53m 49.54s , -35d 43m 51.2s) | C | 180 | 18.0 | Coadd 9798 | 2025-03-17 22:29:50 | MASTER-SAAO | (04h 53m 50.06s , -35d 43m 48.1s) | C | 60 | 17.5 | 9877 | 2025-03-17 22:31:09 | MASTER-SAAO | (04h 53m 50.57s , -35d 43m 45.2s) | C | 60 | 17.4 | 9956 | 2025-03-17 22:32:28 | MASTER-SAAO | (04h 53m 51.09s , -35d 43m 42.4s) | C | 60 | 17.4 | 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/39766. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37781] GRB250312A: Swift/UVOT Upper Limits
by GCN Circulars 17 Mar '25

17 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39765 SUBJECT: GRB250312A: Swift/UVOT Upper Limits DATE: 25/03/17 20:21:01 GMT FROM: Mike Siegel at PSU/Swift MOC <mhs18(a)psu.edu> M. H.Siegel (PSU) and A. Melandri (INAF-OAR) on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 250312A 464s after the BAT trigger (Melandri et al., GCN Circ. 39686). No optical afterglow consistent with the enhanced XRT position (Evans et al., GCN Circ. 39693) is detected in the initial UVOT exposures.Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white (fc) 464 1563 165 >20.47 white 743 1563 223 >20.50 b 718 1539 38 >18.84 b 6529 33943 1081 >20.52 u 6324 23538 403 >19.80 uvw1 21814 22713 885 >19.99 uvm2 10515 16904 1012 >19.85 uvw2 6939 28312 1082 >20.24 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.015 in the direction of the burst (Schlegel et al. 1998). View this GCN Circular online at https://gcn.nasa.gov/circulars/39765. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37780] GRB 250317B: REM optical/NIR observations
by GCN Circulars 17 Mar '25

17 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39764 SUBJECT: GRB 250317B: REM optical/NIR observations DATE: 25/03/17 15:27:41 GMT FROM: Matteo Ferro at INAF-OAB <matteo.ferro(a)inaf.it> M. Ferro, R. Brivio, S. Covino, P. D'Avanzo, D. Fugazza (INAF-OAB) report on behalf of the REM team: We observed the field of the SVOM GRB 250317B (Zhao et al., GCN 39752 & GCN 39753; Götz et al. GCN 39756) with the REM 60 cm robotic telescope located at the ESO observatory of La Silla (Chile). The observations were carried in the g, r, i, z, J, H, and K bands, started on 2025 March 17 at 03:44:41 UT (i.e. 1.54 hr after the burst), and lasted for about 3 hours. From preliminary inspection, we detected the NIR counterpart at the position of the reported optical afterglow (Watson et al., GCN circ. 39754; Palmerio et al., GCN circ. 39755; Pérez-Fournon et al., GCN 39757; Ghosh et al., GCN 39759), with the following magnitude: H = 15.5+-0.3 (Vega; calibrated against the 2MASS catalogue), at a mid-time of 1.62 hours after the trigger. The afterglow is not detected in our r-band observations down to the following 3sigma limit: r > 18.0 (AB; calibrated against the Pan-STARRS catalogue), at a mid-time of 3.05 hours after the trigger. View this GCN Circular online at https://gcn.nasa.gov/circulars/39764. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37779] GRB 250317B: Swift-XRT observations
by GCN Circulars 17 Mar '25

17 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39763 SUBJECT: GRB 250317B: Swift-XRT observations DATE: 25/03/17 15:05:53 GMT FROM: Andrea Melandri at INAF-OAR <andrea.melandri(a)inaf.it> A. Melandri (INAF-OAR), V. D'Elia (SSDC & INAF-OAR), E. Ambrosi, A. D'Ai (INAF-IASFPA) , J.A. Kennea (PSU) 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 GRB 250317B (Zhao et al., GCN circ. 39752 and GCN circ. 39753) and SVOM/MXT (Götz et al., GCN circ. 39756), collecting 1.7 ks of Photon Counting (PC) mode data between T0+10.0 ks and T0+12.9 ks (SVOM burst-id sb25031701). One uncatalogued X-ray source has been detected within the estimated 3-sigma SVOM/MXT error region (Götz et al., GCN circ. 39756), consistent with the optical counterpart (Watson et al., GCN 39754). The source is fading with 3.0-σ significance. Details of this source are given below: Source 1: RA (J2000.0): 211.6427 = 14:06:34.3 Dec (J2000.0): +40.0796 = +40:04:46.7 Error: 3.0 arcsec (radius, 90% conf. [Enhanced position]) Count-rate: 0.19 (±0.04) ct s-1 Flux: 3.7 (±0.4) ×10-12 erg cm-2 s-1 (observed, 0.3-10 keV) 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/SVOM/SVOM_FIELD00003/. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/39763. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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