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

[vsnet-grb-info 28770] Retraction of Fermi GBM GRB 210923A: the trigger is not a GRB
by GCN Circulars 23 Sep '21

23 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30873 SUBJECT: Retraction of Fermi GBM GRB 210923A: the trigger is not a GRB DATE: 21/09/23 22:03:59 GMT FROM: Joe Mangan at UCD <joseph.mangan(a)ucdconnect.ie> J.Mangan (UCD), S.Lesage (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: The Fermi Gamma-ray Burst Monitor (GBM) trigger 654090581/210923493 at 11:49:36.820 UT on 23 September 2021, tentatively classified as a GRB (GCN 30865), is in fact not due to a GRB. This trigger is likely due to a terrestrial electron beam (TEB).

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[vsnet-grb-info 28769] IceCube-210922A: Upper limits from a search for additional neutrino events in IceCube
by GCN Circulars 23 Sep '21

23 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30872 SUBJECT: IceCube-210922A: Upper limits from a search for additional neutrino events in IceCube DATE: 21/09/23 19:44:12 GMT FROM: Alex Pizzuto at ICECUBE/U of Wisconsin <pizzuto(a)wisc.edu> The IceCube Collaboration (http://icecube.wisc.edu/) reports: IceCube has performed a search for additional track-like muon neutrino events arriving from the direction of IceCube-210922A (https://gcn.gsfc.nasa.gov/gcn3/30862.gcn3) in a time range of 2 days centered on the alert event time (2021-09-21 18:17:20.95 UTC to 2021-09-23 18:17:20.95 UTC) during which IceCube was collecting good quality data. Excluding the event that prompted the alert, zero additional track-like events are found in spatial coincidence with the 90% containment region of IceCube-210922A. We accordingly derive a time-integrated muon-neutrino flux upper limit at the alert position of E^2 dN/dE = 3.5 x 10^-5 TeV cm^-2 at 90% CL, under the assumption of an E^-2 power law. 90% of events IceCube would detect from a source at this declination with an E^-2 spectrum are approximately between 2 TeV and 5 PeV. A subsequent search was performed to include the month of data prior to the alert event (2021-08-23 18:17:20.95 UTC to 2021-09-23 18:17:20.95 UTC). In this case, we report a p-value of 1.0, consistent with no significant excess of track-like events, and a corresponding time-integrated muon-neutrino flux upper limit assuming an E^-2 spectrum (E^2 dN/dE) of 4.1 x 10^-5 TeV cm^-2 at the 90% CL. The IceCube Neutrino Observatory is a cubic-kilometer neutrino detector operating at the geographic South Pole, Antarctica. The IceCube realtime alert point of contact can be reached at roc(a)icecube.wisc.edu<mailto:roc@icecube.wisc.edu>.

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[vsnet-grb-info 28768] IceCube-210922A: Upper limits from Fermi-GBM Observations
by GCN Circulars 23 Sep '21

23 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30871 SUBJECT: IceCube-210922A: Upper limits from Fermi-GBM Observations DATE: 21/09/23 15:47:11 GMT FROM: Christian Malacaria at NASA-MSFC/USRA <cmalacaria(a)usra.edu> C. Malacaria (USRA) reports on behalf of the Fermi-GBM team: For the IceCube high-energy neutrino candidate event IceCube-210811A (GCN 30862), at the event time Fermi-GBM was observing the reported neutrino location at: RA: 60.73 (+0.96, -0.66 deg 90% PSF containment) J2000 Dec: -4.18 (+0.42, -0.55 deg 90% PSF containment) J2000 There was no Fermi-GBM onboard trigger around the event time of the neutrino candidate. An automated, blind search for short gamma-ray bursts below the onboard triggering threshold in Fermi-GBM also identified no counterpart candidates. The GBM targeted search, the most sensitive, coherent search for GRB-like signals, was run from +/-30 s around the neutrino candidate time. From this search, no significant signal was found related to IceCube-210922A. We set upper limits on impulsive gamma-ray emission. Using the representative soft, normal, and hard GRB-like templates described in arXiv:1612.02395, we set the following 3 sigma flux upper limits over 10-1000 keV (in units of 10^-7 erg/s/cm^2): Timescale soft norm hard -------------------------------------- 0.128 s: 6.4 11. 14. 1.024 s: 2.1 3.4 4.6 8.192 s: 0.6 0.9 1.4 These results are preliminary.

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[vsnet-grb-info 28767] IceCube-210922A: No Candidate Counterparts from the Zwicky Transient Facility
by GCN Circulars 23 Sep '21

23 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30870 SUBJECT: IceCube-210922A: No Candidate Counterparts from the Zwicky Transient Facility DATE: 21/09/23 15:43:08 GMT FROM: Sven Weimann at Ruhr University Bochum <swei(a)astro.rub.de> Sven Weimann (Ruhr University Bochum), Simeon Reusch, Jannis Necker, Robert Stein (DESY) and Anna Franckowiak (DESY/Ruhr University Bochum), On behalf of the Zwicky Transient Facility (ZTF) and Global Relay of Observatories Watching Transients Happen (GROWTH) collaborations: We observed the localization region of the neutrino event IceCube-210922A (Lincetto et. al, GCN 30862) with the Palomar 48-inch telescope, equipped with the 47 square degree ZTF camera (Bellm et al. 2019, Graham et al. 2019). We started observations in the g- and r-band beginning at 2021-09-23 10:25 UTC, approximately 16.1 hours after event time. We covered 79% (1.2 sq deg) of the reported localization region. This estimate accounts for chip gaps. Each exposure was 300s with a typical depth of 21.0 mag. The images were processed in real-time through the ZTF reduction and image subtraction pipelines at IPAC to search for potential counterparts (Masci et al. 2019). AMPEL (Nordin et al. 2019, Stein et al. 2021) was used to search the alerts database for candidates. We reject stellar sources (Tachibana and Miller 2018) and moving objects, and apply machine learning algorithms (Mahabal et al. 2019). No candidate counterparts were detected. ZTF and GROWTH are worldwide collaborations comprising Caltech, USA; IPAC, USA; WIS, Israel; OKC, Sweden; JSI/UMd, USA; DESY, Germany; TANGO, Taiwan; UW Milwaukee, USA; LANL, USA; TCD, Ireland; IN2P3, France. GROWTH acknowledges generous support of the NSF under PIRE Grant No 1545949. Alert distribution service provided by DIRAC@UW (Patterson et al. 2019). Alert database searches are done by AMPEL (Nordin et al. 2019). Alert filtering is performed with the AMPEL Follow-up Pipeline (Stein et al. 2021).

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[vsnet-grb-info 28766] GECAM observations of a series of bursts from SGR J1935+2154 (2021-09-15T14 to 2021-09-23T14)
by GCN Circulars 23 Sep '21

23 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30869 SUBJECT: GECAM observations of a series of bursts from SGR J1935+2154 (2021-09-15T14 to 2021-09-23T14) DATE: 21/09/23 14:19:30 GMT FROM: Chenwei Wang at IHEP <cwwang(a)ihep.ac.cn> C. W. Wang, S. L. Xiong, Y. Huang, C. Cai, C. Y. Li, X. B. Li, J. C. Liu, X. Y. Song, P. Wang, S. L. Xie, S. Xiao, Z. W. Guo, W. C. Xue, 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 2021-09-15T14 to 2021-09-23T14(UTC). Here is the list of these bursts: Trigger Time (UTC) 2021-09-15T15:32:56.050 2021-09-17T12:52:37.800 2021-09-17T13:58:25.100 2021-09-18T22:58:52.150 2021-09-22T02:39:10.200 2021-09-22T20:12:16.500 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 28765] GRB 210919A: DECam Upper Limits
by GCN Circulars 23 Sep '21

23 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30868 SUBJECT: GRB 210919A: DECam Upper Limits DATE: 21/09/23 14:09:18 GMT FROM: Justin Pierel at STScI <jpierel(a)stsci.edu> J. Pierel (STScI), J. Cooke (Swinburne U.), A. Rest (STScI), R. Foley (UCSC), and R. Ridden-Harper (U. Canterbury) report: We observed the field of GRB210919A (Tohuvavohu et al. GCN 30846) using the Dark Energy Camera (DECam) instrument on the 4m Victor M. Blanco Telescope at CTIO. We obtained 5x250s exposures in the i and z-band from 08:20-09:05 UTC on 2021-09-21. No source is detected inside the enhanced Swfit-XRT uncertainty radius (Goad et al., GCN 30850), to 3-sigma limits of: i>24.1 mag and z>23.6 mag.

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[vsnet-grb-info 28764] Fermi-LAT Gamma-ray Observations of IceCube-210922A
by GCN Circulars 23 Sep '21

23 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30867 SUBJECT: Fermi-LAT Gamma-ray Observations of IceCube-210922A DATE: 21/09/23 13:08:37 GMT FROM: Simone Garrappa at DESY <simone.garrappa(a)desy.de> S. Garrappa (DESY-Zeuthen), S. Buson (Univ. of Wuerzburg) and R. de Menezes (Univ. of Sao Paulo, Univ. of Wuerzburg) on behalf of the Fermi-LAT collaboration: We report an analysis of observations of the vicinity of the high-energy IC210922A neutrino event (GCN 30862) with all-sky survey data from the Large Area Telescope (LAT), on board the Fermi Gamma-ray Space Telescope. The IceCube event was detected on 2021-09-22 at 18:17:20.948 UT (T0) with J2000 position RA = 60.73 (+0.96, -0.66) deg, Decl. = -4.18 (+0.42, -0.55) deg (90% PSF containment). No cataloged gamma-ray (>100 MeV) source is located within the 90% IC210922A localization region (4FGL-DR2, The Fermi-LAT collaboration 2020, ApJS, 247, 33). We searched for intermediate (days to years) timescale emission from a new gamma-ray transient source. Preliminary analysis indicates no significant (> 5 sigma) new excess emission (> 100 MeV) at the IC210922A best-fit position. Assuming a power-law spectrum (photon index = 2.0 fixed) for a point source at the IC210922A best-fit position, the >100 MeV flux upper limit (95% confidence) is < 1.4e-10 ph cm^-2 s^-1 for ~13-years (2008-08-04 to 2021-09-22 UTC), and < 7.5e-9 (< 5.5e-8) ph cm^-2 s^-1 for a 1-month (1-day) integration time before T0. Since Fermi normally operates in an all-sky scanning mode, regular monitoring of this source will continue. For these observations the Fermi-LAT contact persons are S. Garrappa (simone.garrappa at desy.de) and S. Buson (sara.buson at uni-wuerzburg.de). The Fermi-LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden.

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[vsnet-grb-info 28763] Konus-Wind detection of a burst from SGR 1935+2154 on 2021 September 22
by GCN Circulars 23 Sep '21

23 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30866 SUBJECT: Konus-Wind detection of a burst from SGR 1935+2154 on 2021 September 22 DATE: 21/09/23 12:31:24 GMT FROM: Anna Ridnaia at Ioffe Institute <ridnaia(a)mail.ioffe.ru> A. Ridnaia, D. Frederiks, S. Golenetskii, A. Lysenko, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline on behalf of the Konus-Wind team, report: A short, soft, SGR-like burst triggered Konus-Wind on 2021 September 22 at T0=72739.639 s UT (20:12:19.639). The Konus-Wind ecliptic latitude response is consistent with the SGR 1935+2154 position. So, taking in account the ongoing bursting activity of this source, burst time history, and softness of its spectrum (as observed by Konus-Wind), we suggest that this burst is likely originated from SGR 1935+2154. The burst light curve shows a single pulse started at ~T0-100 ms with a total duration of ~172 ms. The emission is seen up to ~200 keV. The Konus-Wind light curve of this burst is available at http://www.ioffe.ru/LEA/SGRs/210922_T72739/ As observed by Konus-Wind, the burst had a fluence of 1.46(-0.08,+0.08)x10^-6 erg/cm2, and a 16-ms peak flux, measured from T0+0.024 s, of 1.59(-0.16,+0.16)x10^-5 erg/cm2/s (both in the 20 - 500 keV energy range). The spectrum of the burst (measured from T0 to T0+0.064 s) is best 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 alpha = -0.13(-0.76,+0.85) and Ep = 37(-6,+4) keV (chi2 = 12/14 dof). All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.

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[vsnet-grb-info 28762] GRB 210923A: Fermi GBM Final Real-time Localization
by GCN Circulars 23 Sep '21

23 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30865 SUBJECT: GRB 210923A: Fermi GBM Final Real-time Localization DATE: 21/09/23 11:57:13 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 SHORT GRB At 11:49:36 UT on 23 Sep 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210923A (trigger 654090581.820056 / 210923493). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 90.0, Dec = -6.5 (J2000 degrees, equivalent to J2000 06h 00m, -6d 30'), with a statistical uncertainty of 10.9 degrees. The angle from the Fermi LAT boresight is 47.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210923493/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210923493/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210923493/…

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[vsnet-grb-info 28761] IceCube Alert 210922.76: Global MASTER-Net observations report
by GCN Circulars 23 Sep '21

23 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30864 SUBJECT: IceCube Alert 210922.76: Global MASTER-Net observations report DATE: 21/09/23 03:13:21 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva, D.Kuvshinov, D. Cheryasov (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. Gres, N.M. Budnev, O.Ershova (Irkutsk State University, API), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), V. Yurkov, A. Gabovich, Yu. Sergienko (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) was pointed to the IceCube Alert 210922.76 (trigger No 30987826,04h 02m 55.20s , -04d 10m 48.0s, R=0.65) errorbox 30295 sec after notice time and 30428 sec after trigger time at 2021-09-23 02:44:29 UT, with upper limit up to 17.5 mag. The observations began at zenith distance = 28 deg. The sun altitude is -22.4 deg. The galactic latitude b = -38 deg., longitude l = 195 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1729682 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 30518 | 2021-09-23 02:44:29 | MASTER-SAAO | (04h 01m 54.27s , -04d 29m 17.4s) | C | 180 | 16.4 | 30661 | 2021-09-23 02:47:51 | MASTER-SAAO | (04h 00m 48.01s , -04d 38m 16.4s) | C | 60 | 17.4 | 30744 | 2021-09-23 02:49:15 | MASTER-SAAO | (04h 08m 46.41s , -04d 39m 25.3s) | C | 60 | 17.5 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.

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