April 2024 - vsnet-grb-info - ooruri.kusastro.kyoto-u.ac.jp

[vsnet-grb-info 34069] GRB 240415B: Swift-XRT observations
by GCN Circulars 22 Apr '24

22 Apr '24

TITLE: GCN CIRCULAR NUMBER: 36226 SUBJECT: GRB 240415B: Swift-XRT observations DATE: 24/04/22 07:23:17 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), E. Ambrosi (INAF-IASFPA) , M. Capalbi (INAF-IASFPA), M. Perri (SSDC & INAF-OAR), D.N. Burrows (PSU) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of the Swift/BAT-detected burst GRB 240415B, collecting 3.4 ks of Photon Counting (PC) mode data between T0+86.1 ks and T0+115.2 ks. Four uncatalogued X-ray sources have been detected consistent with being within 493 arcsec of the Swift/BAT position, however none of them is above the RASS limit or shows definitive signs of fading. Therefore, at the present time we cannot identify which, if any, is the afterglow. Details of these sources are given below: Source 2: RA (J2000.0): 132.2001 = 08:48:48.03 Dec (J2000.0): -27.0714 = -27:04:17.2 Error: 6.4 arcsec (radius, 90% conf.) Count-rate: (9.5 [+10.4, -8.3])e-4 ct s^-1 Distance: 374 arcsec from Swift/BAT position. Source 3: RA (J2000.0): 132.3176 = 08:49:16.23 Dec (J2000.0): -27.1553 = -27:09:19.0 Error: 6.6 arcsec (radius, 90% conf.) Count-rate: (2.6 [+1.6, -1.3])e-3 ct s^-1 Distance: 306 arcsec from Swift/BAT position. Flux: (1.32 [+0.83, -0.68])e-12 erg cm^-2 s^-1 (observed, 0.3-10 keV) Source 6: RA (J2000.0): 132.3018 = 08:49:12.44 Dec (J2000.0): -27.1242 = -27:07:27.0 Error: 5.5 arcsec (radius, 90% conf.) Count-rate: (3.4 [+1.6, -1.3])e-3 ct s^-1 Distance: 200 arcsec from Swift/BAT position. Flux: (4.6 [+2.2, -1.8])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV) Source 7: RA (J2000.0): 132.4111 = 08:49:38.66 Dec (J2000.0): -27.0674 = -27:04:02.8 Error: 5.6 arcsec (radius, 90% conf.) Count-rate: (3.6 [+1.8, -1.5])e-3 ct s^-1 Distance: 301 arcsec from Swift/BAT position. Flux: (8.8 [+4.5, -3.6])e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV) Three uncatalogued sources were also detected too far from the GRB position to be likely afterglow candidates. 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/ToO_GRBs/00021684. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/36226. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 34068] GRB 240415A: Swift-XRT refined Analysis
by GCN Circulars 22 Apr '24

22 Apr '24

TITLE: GCN CIRCULAR NUMBER: 36225 SUBJECT: GRB 240415A: Swift-XRT refined Analysis DATE: 24/04/22 07:22:59 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: We have analysed 5.4 ks of XRT data for GRB 240415A, from 3.3 ks to 26.8 ks after the BAT trigger. The data comprise 281 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=0.97 (+/-0.09). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.18 (+/-0.16). The best-fitting absorption column is 2.2 (+/-0.5) x 10^21 cm^-2, in excess of the Galactic value of 2.5 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 3.3 x 10^-11 (4.9 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 2.2 (+/-0.5) x 10^21 cm^-2 Galactic foreground: 2.5 x 10^20 cm^-2 Excess significance: 6.4 sigma Photon index: 2.18 (+/-0.16) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01221874. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/36225. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 34067] Fermi GRB 240422A: Global MASTER-Net observations report
by GCN Circulars 22 Apr '24

22 Apr '24

TITLE: GCN CIRCULAR NUMBER: 36224 SUBJECT: Fermi GRB 240422A: Global MASTER-Net observations report DATE: 24/04/22 05:31:57 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V. Lipunov, V.Kornilov, E. Gorbovskoy, K. Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, V.Senik, D. Vlasenko, G.Antipov, D.Zimnukhov, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D. Cheryasov, Ya.Kechin, Yu.Tselik, A. Sosnovskij (Lomonosov Moscow State University, SAI, Physics Department), R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix Aguilar OAFA), R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias), D. Buckley (South African Astronomical Observatory), O.A. Gress, N.M. Budnev, O.Ershova (Irkutsk State University, API), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), V. Yurkov, A. Gabovich (Blagoveschensk Educational State University) 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 240422A ( Fermi GBM team, GCN 36222) errorbox 2591 sec after notice time and 2626 sec after trigger time at 2024-04-22 03:24:46 UT, with upper limit up to 19.3 mag. The observations began at zenith distance = 45 deg. The sun altitude is -21.7 deg. The galactic latitude b = -16 deg., longitude l = 324 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2430987 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 2657 | 2024-04-22 03:24:46 | MASTER-SAAO | (18h 35m 02.79s , -76d 43m 27.3s) | C | 60 | 19.1 | 3878 | 2024-04-22 03:45:07 | MASTER-SAAO | (18h 35m 34.85s , -76d 42m 39.4s) | C | 60 | 18.0 | 4038 | 2024-04-22 03:47:47 | MASTER-SAAO | (16h 59m 17.39s , -67d 19m 40.0s) | C | 60 | 18.8 | 4038 | 2024-04-22 03:47:47 | MASTER-SAAO | (16h 54m 35.38s , -67d 06m 21.1s) | C | 60 | 19.1 | 4118 | 2024-04-22 03:49:07 | MASTER-SAAO | (16h 57m 08.53s , -68d 58m 52.2s) | C | 60 | 19.3 | 4118 | 2024-04-22 03:49:07 | MASTER-SAAO | (17h 02m 14.07s , -69d 12m 12.4s) | C | 60 | 19.1 | 4198 | 2024-04-22 03:50:27 | MASTER-SAAO | (16h 53m 26.59s , -65d 11m 30.9s) | C | 60 | 19.1 | 4198 | 2024-04-22 03:50:27 | MASTER-SAAO | (16h 57m 48.08s , -65d 24m 47.4s) | C | 60 | 18.9 | 4277 | 2024-04-22 03:51:46 | MASTER-SAAO | (17h 33m 33.47s , -67d 07m 02.3s) | C | 60 | 19.4 | 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/36224. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 34066] GRB 240421B: AstroSat CZTI detection
by GCN Circulars 22 Apr '24

22 Apr '24

TITLE: GCN CIRCULAR NUMBER: 36223 SUBJECT: GRB 240421B: AstroSat CZTI detection DATE: 24/04/22 04:47:37 GMT FROM: Gaurav Waratkar at IIT Bombay <gauravwaratkar(a)iitb.ac.in> G. Waratkar (IITB), J. Joshi (IUCAA), 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 240421B which was also detected by Swift-BAT (Williams et al., GCN Circ. 36208) and Fermi-GBM (Fletcher et al., GCN Circ. 36218). 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 2024-04-21 09:42:54.5 UTC. The measured peak count rate associated with the burst is 368 (+44, -52) counts/s above the background in the combined data of all quadrants, with a total of 843 (+148, -223) counts. The local mean background count rate was 474 (+5, -4) counts/s. Using cumulative rates, we measure a T90 of 6.3 (+3.2, -2.7) s. It 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 2024-04-21 09:42:53.8 UTC. The measured peak count rate is 745 (+82, -87) counts/s above the background in the combined Veto data of all quadrants, with a total of 1802 (+268, -278) counts. The local mean background count rate was 1740 (+7, -8) counts/s. We measure a T90 of 5.6 (+1.6, -1.7) 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/36223. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 34065] GRB 240422A: Fermi GBM Final Real-time Localization
by GCN Circulars 22 Apr '24

22 Apr '24

TITLE: GCN CIRCULAR NUMBER: 36222 SUBJECT: GRB 240422A: Fermi GBM Final Real-time Localization DATE: 24/04/22 02:51:32 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 02:40:59 UT on 22 Apr 2024, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 240422A (trigger 735446464.467214 / 240422112). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 255.6, Dec = -67.4 (J2000 degrees, equivalent to J2000 17h 02m, -67d 24'), with a statistical uncertainty of 9.9 degrees. The angle from the Fermi LAT boresight is 23.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240422112/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240422112/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240422112/… View this GCN Circular online at https://gcn.nasa.gov/circulars/36222. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 34064] GRB240421B: Zadko Observations
by GCN Circulars 22 Apr '24

22 Apr '24

TITLE: GCN CIRCULAR NUMBER: 36221 SUBJECT: GRB240421B: Zadko Observations DATE: 24/04/22 02:30:22 GMT FROM: Bruce Gendre at UWA <bruce.gendre(a)gmail.com> B. Gendre, E. Moore, F. Panther, D. Coward, J. A. Moore (OzGrav-UWA), and A. Klotz (IRAP-CNRS-OMP), report: We imaged the field of GRB 240421B detected by SWIFT (trigger 1223470) with the Zadko robotic telescope (D=100cm) located at the observatory - Gingin, Australia. The observations started 7.97h after the GRB trigger. The elevation of the field increased from 25 degrees above horizon and weather conditions were good. The date of trigger : t0 = 2024-04-21T09:42:54.050 The first image is 60.0s exposure in tracking mode: t0+28754.8s to t0+28814.8s : R > 16.2 We co-added a series of exposures: t0+28754.8s to t0+29599.3s : R > 17.7 Magnitudes were estimated with the nearby USNO-B1 stars and are not corrected for galactic dust extinction. N.B. Galactic coordinates are lon= 26.7039 lat=-21.4736 and the galactic extinction in R band is 0.7 magnitudes estimated from D. Schlegel et al. 1998ApJ...500..525S. This message may be cited. View this GCN Circular online at https://gcn.nasa.gov/circulars/36221. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 34063] Fermi GRB 240421B: Global MASTER-Net observations report
by GCN Circulars 22 Apr '24

22 Apr '24

TITLE: GCN CIRCULAR NUMBER: 36220 SUBJECT: Fermi GRB 240421B: Global MASTER-Net observations report DATE: 24/04/22 02:15:40 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V. Lipunov, V.Kornilov, E. Gorbovskoy, K. Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, V.Senik, D. Vlasenko, G.Antipov, D.Zimnukhov, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D. Cheryasov, Ya.Kechin, Yu.Tselik, A. Sosnovskij (Lomonosov Moscow State University, SAI, Physics Department), R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix Aguilar OAFA), R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias), D. Buckley (South African Astronomical Observatory), O.A. Gress, N.M. Budnev, O.Ershova (Irkutsk State University, API), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), V. Yurkov, A. Gabovich (Blagoveschensk Educational State University) MASTER-Tavrida robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, SAI Crimea astronomical station) started inspect of the Fermi GRB 240421B ( C. Fletcher (USRA) and C. Meegan (UAH) report on behalf of et al., GCN 36218) errorbox 19358 sec after notice time and 56607 sec after trigger time at 2024-04-22 01:26:08 UT, with upper limit up to 17.1 mag. Observations started at twilight. The observations began at zenith distance = 67 deg. The sun altitude is -14.1 deg. The galactic latitude b = -22 deg., longitude l = 22 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2430649 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 56637 | 2024-04-22 01:26:08 | MASTER-Tavrida | (19h 37m 21.45s , -18d 16m 09.9s) | C | 60 | 16.4 | 56785 | 2024-04-22 01:28:36 | MASTER-Tavrida | (19h 53m 26.05s , -18d 16m 57.8s) | C | 60 | 14.1 | 56858 | 2024-04-22 01:29:50 | MASTER-Tavrida | (19h 49m 21.85s , -22d 05m 18.0s) | C | 60 | 14.2 | 57563 | 2024-04-22 01:41:35 | MASTER-Tavrida | (19h 50m 44.40s , -20d 11m 20.7s) | C | 60 | 15.8 | 57636 | 2024-04-22 01:42:47 | MASTER-Tavrida | (19h 59m 17.11s , -20d 10m 02.0s) | C | 60 | 16.6 | 57709 | 2024-04-22 01:44:00 | MASTER-Tavrida | (19h 37m 21.08s , -18d 16m 19.0s) | C | 60 | 17.1 | 57782 | 2024-04-22 01:45:13 | MASTER-Tavrida | (19h 45m 45.17s , -18d 15m 26.6s) | C | 60 | 17.0 | 57926 | 2024-04-22 01:47:38 | MASTER-Tavrida | (19h 43m 02.18s , -20d 11m 33.0s) | C | 60 | 16.8 | 57999 | 2024-04-22 01:48:50 | MASTER-Tavrida | (19h 53m 25.96s , -18d 17m 25.9s) | C | 60 | 16.7 | 58144 | 2024-04-22 01:51:16 | MASTER-Tavrida | (19h 49m 20.84s , -22d 05m 40.1s) | C | 60 | 14.5 | 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/36220. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 34062] Swift GRB 240421B: Global MASTER-Net observations report
by GCN Circulars 22 Apr '24

22 Apr '24

TITLE: GCN CIRCULAR NUMBER: 36219 SUBJECT: Swift GRB 240421B: Global MASTER-Net observations report DATE: 24/04/22 00:24:46 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V. Lipunov, V.Kornilov, E. Gorbovskoy, K. Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, V.Senik, D. Vlasenko, G.Antipov, D.Zimnukhov, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D. Cheryasov, Ya.Kechin, Yu.Tselik, A. Sosnovskij (Lomonosov Moscow State University, SAI, Physics Department), R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix Aguilar OAFA), R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias), D. Buckley (South African Astronomical Observatory), O.A. Gress, N.M. Budnev, O.Ershova (Irkutsk State University, API), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), V. Yurkov, A. Gabovich (Blagoveschensk Educational State University) 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) was pointed to the Swift GRB 240421B ( M. A. Williams et al., GCN 36208) errorbox 52346 sec after notice time and 52368 sec after trigger time at 2024-04-22 00:15:42 UT, with upper limit up to 16.5 mag. The observations began at zenith distance = 70 deg. The sun altitude is -20.3 deg. The galactic latitude b = -22 deg., longitude l = 27 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2430219 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 52459 | MASTER-Kislovodsk | C | 180 | 15.8 | 52459 | MASTER-Kislovodsk | C | 180 | 16.5 | 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/36219. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 34061] GRB 240421B: Fermi GBM Observation
by GCN Circulars 21 Apr '24

21 Apr '24

TITLE: GCN CIRCULAR NUMBER: 36218 SUBJECT: GRB 240421B: Fermi GBM Observation DATE: 24/04/21 23:05:42 GMT FROM: Cori Fletcher at USRA <cfletcher(a)usra.edu> C. Fletcher (USRA) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 09:42:41.91 UT on 21 April 2024, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 240421B (trigger 735385366/240421405). which was also detected by Swift BAT (M. A. Williams et al. 2024, GCN 36208). The Fermi GBM on-ground location is consistent with the Swift BAT position. The angle from the Fermi LAT boresight is 29 degrees. The GBM light curve consists of multiple peaks with a duration (T90) of about 12.3 s (50-300 keV). The time-averaged spectrum from T0+0.003 to T0+18.4 s is best fit by a Band function with Epeak = 141 +/- 8 keV, alpha = -0.91 +/- 0.04, and beta = -2.31 +/- 0.09. The event fluence (10-1000 keV) in this time interval is (1.28 +/- 0.02)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+12 s in the 10-1000 keV band is 31.9 +/- 0.5 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog: https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html For Fermi GBM data and info, please visit the official Fermi GBM Support Page: https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/" View this GCN Circular online at https://gcn.nasa.gov/circulars/36218. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 34060] GRB 240421B: Swift-XRT refined Analysis
by GCN Circulars 21 Apr '24

21 Apr '24

TITLE: GCN CIRCULAR NUMBER: 36217 SUBJECT: GRB 240421B: Swift-XRT refined Analysis DATE: 24/04/21 22:50:00 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> J.P. Osborne (U. Leicester), B. Sbarufatti (INAF-OAB), C. Salvaggio (INAF-OAB), M. Ferro (INAF-OAB), S. Dichiara (PSU), J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester) and P.A. Evans report on behalf of the Swift-XRT team: We have analysed 6.6 ks of XRT data for GRB 240421B, from 110 s to 36.0 ks after the BAT trigger. The data comprise 42 s in Windowed Timing (WT) mode (the first 9 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. The light curve can be modelled with an initial power-law decay with an index of alpha=0.50 (+/-0.07), followed by a break at T+2500 s to an alpha of 1.20 (+/-0.10). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.87 (+/-0.13). The best-fitting absorption column is 6.5 (+1.0, -0.9) x 10^21 cm^-2, in excess of the Galactic value of 1.2 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 4.6 x 10^-11 (7.3 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 6.5 (+1.0, -0.9) x 10^21 cm^-2 Galactic foreground: 1.2 x 10^21 cm^-2 Excess significance: 9.6 sigma Photon index: 1.87 (+/-0.13) If the light curve continues to decay with a power-law decay index of 1.20, the count rate at T+24 hours will be 0.023 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.1 x 10^-12 (1.7 x 10^-12) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01223470. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/36217. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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