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

[vsnet-grb-info 38016] GRB 250331C: Swift-XRT refined Analysis
by GCN Circulars 01 Apr '25

01 Apr '25

TITLE: GCN CIRCULAR NUMBER: 39997 SUBJECT: GRB 250331C: Swift-XRT refined Analysis DATE: 25/04/01 07:45:44 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> M. A. Williams (PSU), S. Dichiara (PSU), J.A. Kennea (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), M.G. Bernardini (INAF-OAB), E. Ambrosi (INAF-IASFPA) , M. Capalbi (INAF-IASFPA) and P.A. Evans report on behalf of the Swift-XRT team: We have analysed 3.9 ks of XRT data for GRB 250331C, from 137 s to 62.7 ks after the BAT trigger. The data comprise 95 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The light curve can be modelled with a power-law decay with a decay index of alpha=2.81 (+0.11, -0.10). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 2.11 (+0.11, -0.08). The best-fitting absorption column is consistent with the Galactic value of 6.5 x 10^21 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 1.65 (+0.32, -0.30) and a best-fitting absorption column of 9.0 (+3.4, -2.5) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 5.9 x 10^-11 (8.6 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 9.0 (+3.4, -2.5) x 10^21 cm^-2 Galactic foreground: 6.5 x 10^21 cm^-2 Excess significance: <1.6 sigma Photon index: 1.65 (+0.32, -0.30) If the light curve continues to decay with a power-law decay index of 2.81, the count rate at T+24 hours will be 3.2 x 10^-7 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.9 x 10^-17 (2.8 x 10^-17) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01299967. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/39997. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38015] GRB 250331B: Swift-XRT refined Analysis
by GCN Circulars 01 Apr '25

01 Apr '25

TITLE: GCN CIRCULAR NUMBER: 39996 SUBJECT: GRB 250331B: Swift-XRT refined Analysis DATE: 25/04/01 07:45:13 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> P. D'Avanzo (INAF-OAB), D.N. Burrows (PSU), M. A. Williams (PSU), S. Dichiara (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), M.G. Bernardini (INAF-OAB), E. Ambrosi (INAF-IASFPA) and P.A. Evans report on behalf of the Swift-XRT team: We have analysed 5.5 ks of XRT data for GRB 250331B, from 321 s to 35.1 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The light curve can be modelled with a power-law decay with a decay index of alpha=1.11 (+0.17, -0.14). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.2 (+0.9, -0.8). The best-fitting absorption column is 2.1 (+1.5, -1.1) x 10^22 cm^-2, in excess of the Galactic value of 6.6 x 10^21 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 5.7 x 10^-11 (1.6 x 10^-10) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 2.1 (+1.5, -1.1) x 10^22 cm^-2 Galactic foreground: 6.6 x 10^21 cm^-2 Excess significance: 2.2 sigma Photon index: 2.2 (+0.9, -0.8) If the light curve continues to decay with a power-law decay index of 1.11, the count rate at T+24 hours will be 7.9 x 10^-4 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.5 x 10^-14 (1.2 x 10^-13) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01299965. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/39996. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38014] GRB 250331B: Swift-XRT refined Analysis
by GCN Circulars 01 Apr '25

01 Apr '25

TITLE: GCN CIRCULAR NUMBER: 39995 SUBJECT: GRB 250331B: Swift-XRT refined Analysis DATE: 25/04/01 07:45:10 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> T. Sbarrato (INAF-OAB), P. D'Avanzo (INAF-OAB), J.A. Kennea (PSU), D.N. Burrows (PSU), M. A. Williams (PSU), A.P. Beardmore (U. Leicester), J.P. Osborne (U. Leicester), M.G. Bernardini (INAF-OAB) and P.A. Evans report on behalf of the Swift-XRT team: We have analysed 5.5 ks of XRT data for GRB 250331B, from 321 s to 35.1 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The light curve can be modelled with a power-law decay with a decay index of alpha=1.11 (+0.17, -0.14). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.2 (+0.9, -0.8). The best-fitting absorption column is 2.1 (+1.5, -1.1) x 10^22 cm^-2, in excess of the Galactic value of 6.6 x 10^21 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 5.7 x 10^-11 (1.6 x 10^-10) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 2.1 (+1.5, -1.1) x 10^22 cm^-2 Galactic foreground: 6.6 x 10^21 cm^-2 Excess significance: 2.2 sigma Photon index: 2.2 (+0.9, -0.8) If the light curve continues to decay with a power-law decay index of 1.11, the count rate at T+24 hours will be 7.9 x 10^-4 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.5 x 10^-14 (1.2 x 10^-13) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01299965. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/39995. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38013] GRB 250322B possible detection by the AstroSat Satellite
by GCN Circulars 01 Apr '25

01 Apr '25

TITLE: GCN CIRCULAR NUMBER: 39994 SUBJECT: GRB 250322B possible detection by the AstroSat Satellite DATE: 25/04/01 05:55:08 GMT FROM: Tilak Katoch at TIFR <tilak(a)tifr.res.in> Tilak Katoch, H. M. Antia and Parag Shah from TIFR, Mumbai, India report for the LAXPC onboard AstroSat. AstroSat LAXPC data analysis revealed the presence of a strong long duration multiple peaks complex GRB 250322B. The GRB burst profile shows that it was triggered at T0 = 20h 08m 05s UT on 22 Mar 2025, when the satellite was in a normal operating mode and well before and after the SAA region. This multiple peak complex burst profile has been recorded by both LAXPC instruments (LAXPC10 and LAXPC20) in their respective lightcurves. The burst profile observed in these lightcurves lasted for T90 ~ 97 sec. The strongest peak measured has a count rate 526 +/- 28 count/sec in LAXPC10 above the background and 1110 +/- 36 count/sec in LAXPC20 at T0+12 sec. A precursor peak is observed by both LAXPC10 and LAXPC20 at T0-50 sec. LAXPC20 has a nominal energy range of 3-100 keV, but due to the lower gain in LAXPC10, the energy range is approximately 15-400 keV. The background subtracted lightcurves of the LAXPC instruments with 1 sec time bin is available at the website: https://www.tifr.res.in/~astrosat_laxpc/grb250322b.jpg LAXPC was built by TIFR in collaboration with the Indian Space Research Organisation. The Indian Space Research Organisation funded, managed and facilitated the project. View this GCN Circular online at https://gcn.nasa.gov/circulars/39994. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38012] GRB 250330B: SVOM/GRM observation of a short burst
by GCN Circulars 01 Apr '25

01 Apr '25

TITLE: GCN CIRCULAR NUMBER: 39993 SUBJECT: GRB 250330B: SVOM/GRM observation of a short burst DATE: 25/04/01 04:33:43 GMT FROM: Yue Wang <m18509381757(a)163.com> SVOM/GRM team: Yue Wang, Chen-Wei Wang, Jia-Cong Liu, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP) SVOM/ECLAIRs team: O. Godet, Jean-Luc Atteia (IRAP), Frédéric Piron (LUPM), Stéphane Schanne (CEA) Report on behalf of the SVOM team: SVOM/GRM was triggered in-flight by GRB 250330B (SVOM trigger reference: sb25033007) at 2025-03-30T21:52:22.100 (T0). This burst was also detected by Fermi/GBM (Fermi GBM Team, GCN 39951). With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of single main pulse with a T90 of 0.48 +0.32/-0.11 s in the 15-5000 keV band. In addition, ECLAlRs was taking data and did not trigger, since the position of this burst, as determined by Fermi/GBM (GCN 39951, RA: 114.1 deg, DEC: 13.3 deg, Error: 3.1 deg), is located at about 96.2 degrees from the SVOM optical axis, and outside the ECLAIRs field of view. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb250330B.png The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. GRM is developed by the Institute of High Energy Physics (IHEP) of CAS. The SVOM/GRM point of contact for this burst is: Yue Wang (IHEP) (yuewang(a)ihep.ac.cn) View this GCN Circular online at https://gcn.nasa.gov/circulars/39993. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38011] LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Epoch 2)
by GCN Circulars 01 Apr '25

01 Apr '25

TITLE: GCN CIRCULAR NUMBER: 39992 SUBJECT: LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Epoch 2) DATE: 25/04/01 01:35:09 GMT FROM: Isaac McMahon at University of Zürich <isaac.mcmahon(a)ligo.org> S. MacBride (UZH), I. McMahon (UZH), M. Soares-Santos (UZH), K. Herner (Fermilab), S. Kaur (UZH), reporting on behalf of the Dark Energy Survey Gravitational Wave (DESGW) Team: At 01:46 UTC, March 30th, the Dark Energy Camera (DECam) began the second epoch of observations in response to the LVK alert issued for the candidate gravitational-wave event S250328ae (GCN 39898). We observed eight fields centered on the following ICRS coordinates: | RA | DEC | | ---------- | ---------- | | 145.286221 | 10.615360 | | 145.996500 | 12.108130 | | 143.786221 | 10.715360 | | 144.496500 | 12.208130 | | 144.069167 | 9.115670 | | 143.344621 | 7.609550 | | 145.900667 | 13.593470 | | 142.620092 | 6.103430 | These pointings are identical to the first epoch observations from March 29th, 2025 (GCN 39934). All fields were observed in DECam r, i, and z filters with 90-second exposures. The limiting magnitude achieved is ~22.8 in r-band, ~22.5 in i-band, and ~21.9 in z-band. We process the images with our difference imaging pipeline (Herner et al. 2020) using DES and public DECam images as templates. We employ the autoscan machine learning code (Goldstein et al 2015) to reject subtraction artifacts, requiring an autoscan score of at least 0.7 on both nights of observations. We also match our candidates against the ALLWISE, Milliquas, Quaia, and LQAC-6 AGN catalogs (Secrest et al 2015, Flesch 2023, Storey-Fisher et al 2024, Souchay et al 2024) within the LVK localization volume. After candidate selection, we report 25 high confidence candidates listed below. After vetting and identification, 15 candidates are classified as nuclear candidates (likely active galactic nuclei) and 10 candidates as possible supernovae. No candidates from the second epoch of observations match known AGNs within 1 arcsecond. 12 of the 20 candidates in the first epoch are listed here, while the candidates which do not appear did not have a confident detection in the second epoch. We also do not recover any of the X-ray source candidates reported by Swift XRT (GCN 39972) within their reported error bounds. | TYPE | ID | ATNAME | RA | DEC | MAG_R | MAG_R_ERR | MAG_I | MAG_I_ERR | MAG_Z | MAG_Z_ERR | | -------- | ------- | --------- | ---------- | ---------- | ----- | ---- | ----- | ---- | ----- | ---- | | SN_LIKE | 2290036 | AT2025gek | 145.199481 | 10.828527 | 20.77 | 0.04 | 20.62 | 0.03 | 20.69 | 0.1 | | SN_LIKE | 2290467 | AT2020woa | 144.388798 | 10.255536 | 19.87 | 0.02 | N/A | N/A | 20.1 | 0.04 | | SN_LIKE | 2292782 | AT2025geo | 144.928578 | 10.349243 | 20.92 | 0.04 | 21.07 | 0.04 | N/A | N/A | | SN_LIKE | 2290001 | AT2025avp | 144.806008 | 10.632223 | 20.36 | 0.02 | 20.19 | 0.02 | 20.22 | 0.06 | | SN_LIKE | 2290334 | AT2025geq | 145.235616 | 12.469694 | 20.22 | 0.02 | 20.57 | 0.03 | 21.11 | 0.11 | | AGN_LIKE | 2290623 | AT2025gen | 144.112464 | 11.641817 | 21.4 | 0.04 | 21.3 | 0.08 | 21.37 | 0.12 | | AGN_LIKE | 2291223 | N/A | 146.389563 | 13.131801 | 20.56 | 0.02 | 20.64 | 0.04 | 20.52 | 0.05 | | SN_LIKE | 2291473 | AT2025gem | 144.706509 | 11.560317 | 20.92 | 0.03 | N/A | N/A | 21.22 | 0.1 | | SN_LIKE | 2293190 | AT2025cvb | 144.191297 | 10.828462 | 20.86 | 0.03 | 20.87 | 0.03 | N/A | N/A | | SN_LIKE | 2290143 | AT2025ggv | 146.033906 | 11.088812 | 21.26 | 0.05 | 21.46 | 0.07 | 21.47 | 0.13 | | AGN_LIKE | 2292003 | N/A | 144.007084 | 9.336975 | 21.18 | 0.03 | 21.16 | 0.05 | 21.6 | 0.11 | | SN_LIKE | 2292854 | AT2025ggw | 142.67125 | 6.637349 | N/A | N/A | 20.75 | 0.04 | 20.72 | 0.06 | | AGN_LIKE | 2290453 | N/A | 146.299999 | 13.629839 | 21.7 | 0.06 | 21.89 | 0.11 | 22.14 | 0.19 | | AGN_LIKE | 2292040 | AT2025ges | 144.438216 | 9.885617 | 21.72 | 0.07 | 21.75 | 0.11 | 21.93 | 0.17 | | AGN_LIKE | 2290059 | N/A | 144.679961 | 10.018211 | N/A | N/A | 20.26 | 0.03 | 21.11 | 0.12 | | AGN_LIKE | 2290970 | AT2025ger | 142.543835 | 6.090899 | 21.71 | 0.05 | 21.43 | 0.06 | 21.28 | 0.09 | | AGN_LIKE | 2294074 | AT2025gew | 144.291829 | 8.349302 | 22.23 | 0.1 | 21.85 | 0.11 | 22.28 | 0.15 | | AGN_LIKE | 2292786 | N/A | 144.037664 | 10.810454 | 22.27 | 0.08 | 22.12 | 0.11 | 22.89 | 0.25 | | AGN_LIKE | 2293517 | AT2025geu | 145.956024 | 12.381673 | 21.73 | 0.08 | 21.65 | 0.07 | 21.51 | 0.14 | | AGN_LIKE | 2295862 | N/A | 145.361115 | 12.521385 | 22.44 | 0.11 | 23.33 | 0.36 | 23.47 | 0.46 | | AGN_LIKE | 2290563 | N/A | 145.149074 | 11.756403 | 23.41 | 0.33 | 22.11 | 0.11 | 22.3 | 0.24 | | AGN_LIKE | 2290298 | N/A | 144.167668 | 10.985136 | 21.59 | 0.05 | 21.99 | 0.12 | 21.1 | 0.1 | | SN_LIKE | 2289995 | AT2025ggx | 144.57373 | 10.274445 | 22.62 | 0.19 | 22.31 | 0.14 | 21.7 | 0.22 | | AGN_LIKE | 2291169 | N/A | 145.423743 | 11.834742 | 22.57 | 0.14 | 23.44 | 0.34 | 22.8 | 0.46 | | AGN_LIKE | 2293519 | N/A | 143.751725 | 9.714206 | 22.75 | 0.15 | 22.23 | 0.14 | 21.63 | 0.12 | We encourage followup of the 25 candidates identified herein. The DECam Search & Discovery Program for Optical Signatures of Gravitational Wave Events (DESGW) is carried out by the Dark Energy Survey (DES) collaboration in partnership with wide-ranging groups in the community. DESGW uses data obtained with the Dark Energy Camera (DECam), which was constructed by the DES collaboration with support from the Department of Energy and member institutions, and utilizes data as distributed by the Science Data Archive at NOIRLAB. NOIRLAB is operated by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation. We thank the Cerro Tololo observatory staff for their support in acquiring these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/39992. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38010] Fermi GRB 250331E: Global MASTER-Net observations report
by GCN Circulars 01 Apr '25

01 Apr '25

TITLE: GCN CIRCULAR NUMBER: 39991 SUBJECT: Fermi GRB 250331E: Global MASTER-Net observations report DATE: 25/04/01 01:16:06 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 GRB 250331E ( Fermi GBM team, GCN 39988) errorbox 4 sec after trigger time at 2025-03-31 22:46:37 UT, with upper limit up to 19.3 mag. The observations began at zenith distance = 12 deg. The sun altitude is -62.4 deg. The galactic latitude b = 35 deg., longitude l = 308 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2829592 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 35 | 2025-03-31 22:46:37 | MASTER-SAAO | (12h 57m 48.00s , -20d 04m 42.7s) | C | 60 | 19.0 | 114 | 2025-03-31 22:47:56 | MASTER-SAAO | (13h 06m 14.94s , -20d 06m 25.5s) | C | 60 | 19.1 | 1229 | 2025-03-31 23:06:32 | MASTER-SAAO | (13h 25m 08.68s , -32d 04m 39.4s) | C | 60 | 19.0 | 1388 | 2025-03-31 23:09:10 | MASTER-SAAO | (13h 34m 31.38s , -32d 07m 08.5s) | C | 60 | 19.2 | 2434 | 2025-03-31 23:26:37 | MASTER-SAAO | (13h 25m 13.32s , -32d 05m 29.0s) | C | 60 | 19.2 | 2593 | 2025-03-31 23:29:15 | MASTER-SAAO | (14h 07m 32.41s , -36d 55m 59.7s) | C | 60 | 19.3 | 3468 | 2025-03-31 23:43:50 | MASTER-SAAO | (14h 07m 42.96s , -36d 54m 45.6s) | C | 60 | 19.1 | 4282 | 2025-03-31 23:57:24 | MASTER-SAAO | (14h 07m 44.51s , -36d 53m 28.5s) | C | 60 | 19.1 | 5764 | 2025-04-01 00:22:06 | MASTER-SAAO | (14h 07m 53.30s , -36d 53m 01.5s) | C | 60 | 19.1 | 6499 | 2025-04-01 00:34:21 | MASTER-SAAO | (14h 07m 57.57s , -36d 54m 12.1s) | C | 60 | 19.2 | 7157 | 2025-04-01 00:45:19 | MASTER-SAAO | (14h 07m 59.18s , -36d 53m 44.9s) | C | 60 | 19.1 | 7236 | 2025-04-01 00:46:38 | MASTER-SAAO | (13h 35m 38.73s , -27d 21m 54.8s) | C | 60 | 19.1 | 7315 | 2025-04-01 00:47:58 | MASTER-SAAO | (13h 44m 37.58s , -27d 21m 15.5s) | C | 60 | 19.3 | 7474 | 2025-04-01 00:50:36 | MASTER-SAAO | (13h 22m 32.82s , -25d 27m 53.6s) | C | 60 | 19.3 | 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/39991. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38009] Fermi GRB 250331D: Global MASTER-Net observations report
by GCN Circulars 01 Apr '25

01 Apr '25

TITLE: GCN CIRCULAR NUMBER: 39990 SUBJECT: Fermi GRB 250331D: Global MASTER-Net observations report DATE: 25/04/01 00:03:05 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-Kislovodsk robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB 250331D ( Fermi GBM team, GCN 39961) errorbox 62486 sec after notice time and 62523 sec after trigger time at 2025-03-31 23:11:20 UT, with upper limit up to 17.9 mag. The observations began at zenith distance = 71 deg. The sun altitude is -35.8 deg. The galactic latitude b = -7 deg., longitude l = 128 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2829033 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 62554 | 2025-03-31 23:11:20 | MASTER-Kislovodsk | (02h 54m 34.96s , +65d 33m 33.8s) | C | 60 | 17.7 | 63431 | 2025-03-31 23:25:58 | MASTER-Kislovodsk | (02h 54m 36.68s , +65d 33m 23.8s) | C | 60 | 17.9 | 64508 | 2025-03-31 23:43:54 | MASTER-Kislovodsk | (02h 53m 45.13s , +65d 44m 21.5s) | C | 60 | 17.7 | 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/39990. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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