September 2021 - vsnet-grb-info - ooruri.kusastro.kyoto-u.ac.jp

[vsnet-grb-info 28740] GRB 210917A: Fermi GBM Final Real-time Localization
by GCN Circulars 17 Sep '21

17 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30843 SUBJECT: GRB 210917A: Fermi GBM Final Real-time Localization DATE: 21/09/17 03:56:05 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 03:45:47 UT on 17 Sep 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210917A (trigger 653543152.223672 / 210917157). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 75.5, Dec = -36.2 (J2000 degrees, equivalent to J2000 05h 01m, -36d 12'), with a statistical uncertainty of 5.6 degrees. The angle from the Fermi LAT boresight is 90.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210917157/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210917157/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210917157/…

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[vsnet-grb-info 28739] GRB 210812A is not a compelling example of a lensed GRB
by GCN Circulars 15 Sep '21

15 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30842 SUBJECT: GRB 210812A is not a compelling example of a lensed GRB DATE: 21/09/15 23:50:45 GMT FROM: Robert Nemiroff at Michigan Tech. <nemiroff(a)mtu.edu> Oindabi Mukherjee (Michigan Tech U.) & Robert J. Nemiroff (Michigan Tech U.) report: A preliminary light curve and hardness comparison between the two main pulses of GRB 210812A has been done using Fermi GBM data to test for gravitational lensing (as suggested by Veres et al. 2021, GCN 30645). First, an amplitude-equalized light curve comparison of combined energy bands 3 through 7 in detectors 2, 7, 8, 9, 10, 11, and 12 shows a chi^2 difference of 2.796 sigma, so that there is only a 0.52% chance of the two pulses being randomly drawn from the same pulse. Additionally, a hardness analysis shows that in energy channels 4 and 5, the hardness difference between the two pulses differs at the 2.24 sigma level, with the second pulse being softer. These preliminary results suggest that although the case of GRB 210812A is interesting, it is not a compelling example of a GRB gravitational lens. A more thorough analysis is ongoing.

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[vsnet-grb-info 28738] GECAM observations of bursts from SGR J1935+2154 (2021-09-13T01 to 2021-09-15T14)
by GCN Circulars 15 Sep '21

15 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30841 SUBJECT: GECAM observations of bursts from SGR J1935+2154 (2021-09-13T01 to 2021-09-15T14) DATE: 21/09/15 14:40:52 GMT FROM: Shuo Xiao at IHEP <xiaoshuo(a)ihep.ac.cn> C. Y. Li, C. Cai, S. L. Xiong, Y. Huang, W. C. Xue, Z. W. Guo, X. B. Li, J. C. Liu, X. Y. Song, C. W. Wang, P. Wang, S. L. Xie, S. Xiao, Q. B. Yi, Y. Q. Zhang, G. Y. Zhao, X. Y. Zhao, Y. Zhao, C. Zheng, W. Chen, Y. Q. Du, D. Y. Guo, J. J. He, J. Liang, F. J. Lu, Q. Luo, X. Ma, W. X. Peng, R. Qiao, L. M. Song, J. Wang, H. Wu, P. Zhang, S. N. Zhang, X. L. Zhang, Z. Zhang, S. J. Zheng (IHEP), report on behalf of GECAM team: GECAM-B detected a series of bursts very probably from SGR J1935+2154, either by in-flight trigger or by on-ground search of the data, from 2021-09-13T01 to 2021-09-15T14 (UTC). Here is the list of these bursts: Trigger Time (UTC) 2021-09-13T14:12:39.650 2021-09-13T19:51:32.950 2021-09-14T11:10:36.250 2021-09-14T14:15:42.900 2021-09-14T23:21:58.500 2021-09-14T23:26:34.050 2021-09-15T02:35:47.350 2021-09-15T02:39:25.700 Locations of all these bursts are consistent with SGR J1935+2154. Please note that all GECAM results here are preliminary.

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[vsnet-grb-info 28737] GRB 210909A: Detection by GRBAlpha
by GCN Circulars 15 Sep '21

15 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30840 SUBJECT: GRB 210909A: Detection by GRBAlpha DATE: 21/09/15 10:35:12 GMT FROM: Masanori Ohno at Hiroshima U <ohno(a)astro.hiroshima-u.ac.jp> J. Ripa (Masaryk U.), M. Ohno (Eotvos U./Konkoly Observatory/Hiroshima U.), H. Takahashi (Hiroshima U.), A. Pal, L. Meszaros, B. Csak (Konkoly Observatory), N. Werner, M. Topinka, F. Munz, F. Hroch (Masaryk U.), T. Urbanec, M. Kasal, A. Povalac (Brno U. of Technology), J. Hudec, J. Kapus, M. Frajt (Spacemanic s.r.o), R. Laszlo, M. Koleda (Needronix s.r.o), M. Smelko, P. Hanak, P. Lipovsky (Technical U. of Kosice), G. Galgoczi (Wigner Research Center/Eotvos U.), Yuusuke Uchida, Helen Poon, H. Matake, N. Uchida (Hiroshima U.), T. Bozoki (Eotvos U.), G. Dalya (Eotvos U.), T. Enoto (Kyoto U.), Zs. Frei (Eotvos U.), G. Friss (Eotvos U.), Y. Fukazawa, K. Hirose (Hiroshima U.), S. Hisadomi (Nagoya U.), Y. Ichinohe (Rikkyo U.), K. Kapas (Eotvos U.), L. L. Kiss (Konkoly Observatory), T. Mizuno (Hiroshima U.), K. Nakazawa (Nagoya U.), H. Odaka (Univ of Tokyo), J. Takatsy (Eotvos U.), K. Torigoe (Hiroshima U.) -- the GRBAlpha collaboration. The short duration GRB 210909A (Fermi-GBM detection; GCN Circ. 30786) was detected by the GRBAlpha 1U CubeSat (Pal et al. Proc. SPIE 2020). The light curve shows a short spike structure within the 4 s time bin. The detection had significance of the SNR = 8.8. The light curve obtained by GRBAlpha is available here: https://grbalpha.konkoly.hu/static/share/GRB210909A_GCN.pdf GRBAlpha is a demonstration mission for a future CubeSats constellation (Werner et al. Proc. SPIE 2018). The detector of GRBAlpha consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from ~50 keV to ~1000 keV. GRBAlpha was launched on 2021 March 22 from Baikonur. After its commissioning phase, the scientific observations are now under way. To increase the duty cycle and the downlink rate, the upgrade of the on-board data acquisition software stack is in progress. The ground segment is also supported by the radio amateur community and it takes advantage of the SatNOGS network for increased data downlink volume.

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[vsnet-grb-info 28736] GRB 210912A: Swift-BAT refined analysis
by GCN Circulars 13 Sep '21

13 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30839 SUBJECT: GRB 210912A: Swift-BAT refined analysis DATE: 21/09/13 23:34:08 GMT FROM: Sibasish Laha at GSFC <sibasish.laha(a)nasa.gov> M. Stamatikos (OSU), S. D. Barthelmy (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), (i.e. the Swift-BAT team): Using the data set from T-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 210912A (trigger #1072990) (Troja et al., GCN Circ. 30820). The BAT ground-calculated position is RA, Dec = 129.874, 79.216 deg which is RA(J2000) = 08h 39m 29.7s Dec(J2000) = +79d 12' 59.3" with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment). The partial coding was 100%. The BAT light curve showed a complex structure with a duration of about ~30 sec. T90 (15-350 keV) is 28.35 +- 14.34 sec (estimated error including systematics). The time-averaged spectrum from T-23 to T+25 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.61 +- 0.13. The fluence in the 15-150 keV band is 1.1 +- 0.1 x 10^-06 erg/cm2. The 1-sec peak photon flux measured from T+0.23 sec in the 15-150 keV band is 1.7 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence level. The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/1072990/BA/

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[vsnet-grb-info 28735] Konus-Wind observation of the recent SGR 1935+2154 activity
by GCN Circulars 13 Sep '21

13 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30838 SUBJECT: Konus-Wind observation of the recent SGR 1935+2154 activity DATE: 21/09/13 17:56:37 GMT FROM: Anna Ridnaia at Ioffe Institute <ridnaia(a)mail.ioffe.ru> A. Ridnaia, S. Golenetskii, D. Frederiks, M. Ulanov, D. Svinkin, A. Tsvetkova, A. Lysenko, and T. Cline on behalf of the Konus-Wind team, report: Since the last KW GCN on the ongoing SGR 1935+2154 activity (Ridnaia et al., GCN 30803) the instrument triggered on four bright bursts from the source. The following is a list of the Konus-Wind triggers with preliminary estimates of the burst fluences and peak fluxes. ------------------------------------------------------------------ # Date T0(KW) s UT Fl* PF** ------------------------------------------------------------------ 1 20210911 54406.825 s UT(15:06:46.825) 5.38 +/-0.15 22.6 +/-1.6 2 20210911 61274.025 s UT(17:01:14.025) 7.84 +/-0.21 18.5 +/-1.4 3 20210912 24677.185 s UT(06:51:17.185) 4.96 +/-0.14 26.6 +/-1.7 4 20210912 28904.121 s UT(08:01:44.121) 1.25 +/-0.02 17.0 +/-1.4 ------------------------------------------------------------------ * - Fluence (20-500 keV) in units of 1e-6 erg/cm2 ** - Peak Flux (20-500 keV) on 16-ms time scale in units of 1e-6 erg/cm2/s The time-averaged spectra of the bursts are well fit in the 20 - 200 keV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with the following parameters: ------------------------------------------------------------------ # T100 Tbeg-Tend alpha Ep(keV) chi2/dof ------------------------------------------------------------------ 1 0.392 0 - 0.256 0.47(-0.32,+0.33) 42(-2,+2) 30/20 2 1.243 0 - 8.448 0.40(-0.37,+0.39) 37(-2,+1) 36/28 3 0.452 0 - 0.256 0.20(-0.35,+0.37) 38(-2,+2) 17/19 4 1.600 0 - 8.448 -0.10(-0.21,+0.22) 35(-1,+1) 43/29 ------------------------------------------------------------------ The emission in all bursts is seen up to ~200 keV. The Konus-Wind light curves of the bursts are available at http://www.ioffe.ru/LEA/SGRs/210911_T54406/ http://www.ioffe.ru/LEA/SGRs/210911_T61274/ http://www.ioffe.ru/LEA/SGRs/210912_T24677/ http://www.ioffe.ru/LEA/SGRs/210912_T28904/ All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.

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[vsnet-grb-info 28734] GRB 210912A: Tautenburg observations
by GCN Circulars 13 Sep '21

13 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30837 SUBJECT: GRB 210912A: Tautenburg observations DATE: 21/09/13 16:25:04 GMT FROM: Ana Nicuesa at TLS Tautenburg <ana(a)tls-tautenburg.de> A. Nicuesa Guelbenzu, S. Klose, S. Melnikov, B. Stecklum, C. Hoegner (all TLS Tautenburg) report: We observed the field of GRB 210912A (Troja et al., GCN 30820) with the Tautenburg 1.34m Schmidt telescope equipped with the TAUKAM 6kx6k CCD camera and the Sloan r-band filter. Observations were performed on September 12, at a midtime of 19.33 UT, 22.17 UT, and 02:36 UT (Sep 13). The optical transient (Hu et al., GCN 30823; Pankov et al., GCN 30825; Kuin & Troja, GCN 30832; Kann et al. GCN 30833) is detected with the following preliminary AB magnitudes: r_1 = 21.95 +- 0.19, r_2 = 22.17 +- 0.19, r_3 = 22.53 +- 0.19. Magnitudes are calibrated against the Pan-STARRS catalogue. A comparison with the previous observations suggests that around 0.6 days the decay index of the light curve has increased from a rather modest value of alpha = 0.4 to alpha about 1. Further observations are required in order to provide a more precise decay index.

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[vsnet-grb-info 28733] GECAM observations of bursts from SGR J1935+2154 (2021-09-12T05 to 2021-09-13T01)
by GCN Circulars 13 Sep '21

13 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30836 SUBJECT: GECAM observations of bursts from SGR J1935+2154 (2021-09-12T05 to 2021-09-13T01) DATE: 21/09/13 15:03:09 GMT FROM: Ce Cai at IHEP <caice(a)ihep.ac.cn> C. Cai, S. L. Xiong, Y. Huang, W. C. Xue, Z. W. Guo, C. Y. Li, X. B. Li, J. C. Liu, X. Y. Song, C. W. Wang, P. Wang, S. L. Xie, S. Xiao, Q. B. Yi, Y. Q. Zhang, G. Y. Zhao, X. Y. Zhao, Yi Zhao, C. Zheng, W. Chen, Y. Q. Du, D. Y. Guo, J. J. He, J. Liang, F. J. Lu, Q. Luo, X. Ma, W. X. Peng, R. Qiao, L. M. Song, J. Wang, H. Wu, P. Zhang, S. N. Zhang, X. L. Zhang, Z. Zhang, S. J. Zheng (IHEP), report on behalf of GECAM team: GECAM-B detected a series of bursts very probably from SGR J1935+2154, either by in-flight trigger or by on-ground search of the data, from 2021-09-12T05 to 2021-09-13T01. Here is the list of these bursts: Trigger Time (UTC) 2021-09-12T05:44:17.050 2021-09-12T16:26:08.150 2021-09-12T16:52:07.950 2021-09-12T22:16:36.200 2021-09-13T00:27:25.200 Locations of all these bursts are consistent with SGR J1935+2154. Please note that all GECAM results here are preliminary.

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[vsnet-grb-info 28732] AGILE observations of two bright bursts from SGR 1935+2154
by GCN Circulars 13 Sep '21

13 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30835 SUBJECT: AGILE observations of two bright bursts from SGR 1935+2154 DATE: 21/09/13 13:06:58 GMT FROM: Alessandro Ursi at INAF/IAPS <alessandro.ursi(a)gmail.com> A. Ursi (INAF/IAPS), E. Menegoni, L. Foffano (INAF/IAPS), V. Fioretti (INAF/OAS-Bologna), C. Pittori, F. Verrecchia (SSDC, and INAF/OAR), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), A. Argan, M. Cardillo, C. Casentini, Y. Evangelista, L. Pacciani, G. Piano (INAF/IAPS), F. Lucarelli (SSDC, and INAF/OAR), A. Bulgarelli, F. Fuschino, N. Parmiggiani (INAF/OAS-Bologna), M. Marisaldi (INAF/OAS-Bologna, and Bergen University), M. Pilia, A. Trois (INAF/OA-Cagliari), I. Donnarumma (ASI), F. Longo (Univ. Trieste and INFN Trieste), A. Giuliani (INAF/IASF-Mi), report on behalf of the AGILE Team: The AGILE satellite clearly detected the two bright bursts from the SGR1935+2154, at T1 = 2021-09-10 00:45:47 s (UTC), reported by Konus-Wind (GCN #30804), Fermi GBM (GCN #30806), and GECAM (GCN #30822), and at T2 = 2021-09-12 20:16:10 s (UTC), reported by Fermi GBM (GCN #30831). The bursts are clearly visible in the AGILE scientific ratemeters of the SuperAGILE (SA; 20-60 keV) and AntiCoincidence (AC; 50-200 keV) detectors. The first event lasted about 2 s and it released a total number of 560 counts in the SA detector (above a background rate of 65 Hz), and 8730 counts in the AC detector (above a background rate of 3450 Hz). The AGILE ratemeter light curves can be found at http://www.agilescienceapp.it/notices/burst210910_AGILE_RM.png . At T1, the SGR1935+2154 was 150 deg off-axis for AGILE. The second event lasted 2 s and it released a total number of 620 counts in the SA detector (above a background rate of 100 Hz), and 8170 counts in the AC detector (above a background rate of 3500 Hz). The AGILE ratemeter light curves can be found at http://www.agilescienceapp.it/notices/burst210912_AGILE_RM.png . At T2, the SGR1935+2154 was 37 deg off-axis for AGILE. Additional analysis of AGILE data is in progress.

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[vsnet-grb-info 28731] GRB 210912A: CAHA 2.2m Detection
by GCN Circulars 13 Sep '21

13 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30834 SUBJECT: GRB 210912A: CAHA 2.2m Detection DATE: 21/09/13 09:35:41 GMT FROM: Alexander Kann at IAA-CSIC <kann(a)iaa.es> D. A. Kann (HETH/IAA-CSIC), A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), C. Thoene, M. Blazek, J. F. Agui Fernandez (all HETH/IAA-CSIC), and S. Gongora (CAHA) report: We observed GRB 210912A (Swift detection: Troja et al., GCN #30820) with CAFOS mounted on the 2.2m CAHA telescope at Calar Alto, Almeria, Spain. We obtained 7 x 60 s in the SDSS i' band under passing clouds, starting at 20:04:34 UT (9.056 hrs after the trigger; further observations at a later time were prevented by cloud cover). The afterglow (Hu et al., GCN #30823; Pankov et al., GCN #30825; Kuin & Troja, GCN #30832) is faintly detected in the stacked image. Compared to a nearby Pan-STARRS comparison star, we measure (AB mag) i' = 21.66 +/- 0.15 mag at 0.38146 d after the GRB, further confirming the decaying afterglow. This is still significantly brighter than the potential underlying host galaxy (Kann, GCN #30829).

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