//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26655 SUBJECT: IceCube-200107A: IceCube observation of a high-energy neutrino candidate event DATE: 20/01/07 17:36:04 GMT FROM: Robert Stein at DESY The IceCube Collaboration (http://icecube.wisc.edu/) reports: On 20/01/07 at 09:42:18.36 UT IceCube detected a high-energy starting event [1]. Though it did not pass the Gold or Bronze starting track classification, a new neural network classifier identified the event as a starting track. Visual inspection is consistent with this classification. High-energy starting events have a rate of ~12 per year, out of which ~2 per year are starting tracks. Because the event was not identified as either Gold or Bronze, we do not currently report a false alert rate or signalness. However, given the topology and light deposition of this event, we identify it as a potential astrophysical neutrino of interest to the community. The IceCube detector was in a normal operating state at the time of detection. Sophisticated reconstruction algorithms have been applied offline, with the direction refined to: Date: 20/01/07 Time: 09:42:18.36 UT RA: 148.18 (+ 2.20 - 1.83 deg 90% PSF containment) J2000 Dec: 35.46 (+ 1.10 - 1.22 deg 90% PSF containment) J2000 We encourage follow-up by ground and space-based instruments to help identify a possible astrophysical source for the candidate neutrino. There are two Fermi 4FGL sources located within the 90% localization region. The nearest gamma-ray source is 4FGL J0955.1+3551 at RA: 148.78 deg, Dec: 35.86 deg (0.63 deg away from the best-fit event position). Another source, 4FGL J0957.8+3423, is located at RA: 149.47 deg, Dec: 34.40 (1.50 deg away from the best-fit event position). 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@icecube.wisc.edu [1] The IceCube Collaboration, Phys. Rev. Lett. 113, 101101 (2014) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26656 SUBJECT: IceCube-200107A: Upper limits from Fermi-GBM Observations DATE: 20/01/07 18:28:26 GMT FROM: Peter Veres at UAH P. Veres (UAH) reports on behalf of the Fermi-GBM team: For the IceCube high-energy neutrino candidate event IceCube-200107A (GCN 26655), at the event time Fermi-GBM was observing the reported neutrino location at: RA: 148.18 (+ 2.20 - 1.83 deg 90% PSF containment) J2000 Dec: 35.46 (+ 1.10 - 1.22 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-200107A. 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 Normal Hard ------------------------------------------- 0.128 s: 6.7 15 25 1.024 s: 2.1 4.3 7.2 8.192 s: 0.79 1.2 1.8 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26666 SUBJECT: IceCube-200107A: No counterpart candidates in INTEGRAL SPI-ACS prompt observation DATE: 20/01/08 11:28:39 GMT FROM: Alexis Coleiro at APC/U. Paris Diderot Alexis Coleiro (APC, France), Carlo Ferrigno (ISDC/UniGE, Switzerland), V. Savchenko (ISDC/UniGE, Switzerland), J. Rodi (IAPS-Roma, Italy), S. Mereghetti (INAF IASF-Milano, Italy) on behalf of the INTEGRAL multi-messenger collaboration: https://www.astro.unige.ch/cdci/integral-multimessenger-collaboration Using INTEGRAL/SPI-ACS realtime data (following [1]) we have performed a search for a prompt gamma-ray counterpart of IceCube-200107A (GCN 26655). At the time of the event (2020-01-07 09:42:18 UTC, hereafter T0), INTEGRAL was operating in nominal mode. The peak of the event localization probability was at an angle of 78 deg with respect to the spacecraft pointing axis. This orientation implies strongly suppressed (24% of optimal) response of ISGRI, strongly suppressed (40% of optimal) response of IBIS/Veto, and near-optimal (70% of optimal) response of SPI-ACS. The background within +/-300 seconds around the event was somewhat unstable (excess variance 1.8). We have performed a search for any impulsive events in INTEGRAL SPI- ACS (as described in [2]) data (IBIS data are not considered since they are only partially available in the search region due to the instrument starting the observations after the perigee shortly before the IceCube trigger). We do not detect any significant counterparts and estimate a 3-sigma upper limit on the 75-2000 keV fluence of 2.8e-07 erg/cm^2 (within the 50% probability containment region of the source localization) for a burst lasting less than 1 s with a characteristic short GRB spectrum (an exponentially cut off power law with alpha=-0.5 and Ep=600 keV) occurring at any time in the interval within 300 s around T0. For a typical long GRB spectrum (Band function with alpha=-1, beta=-2.5, and Ep=300 keV), the derived peak flux upper limit is ~2.4e-07 (1.2e-07) erg/cm^2/s at 1 s (8 s) time scale in 75-2000 keV energy range. We report for completeness and in order of FAP, all excesses identified in the search region. We find 4 likely background excesses: T-T0 | scale | S/N | flux ( x 1e-06 erg/cm2/s) | FAP 12.5 | 0.45 | 3.3 | 0.432 +/- 0.122 +/- 0.117 | 0.328 -64.5 | 0.9 | 3.4 | 3.33 +/- 0.863 +/- 0.9 | 0.663 -41.5 | 0.15 | 4.3 | 0.939 +/- 0.213 +/- 0.254 | 0.681 -86.8 | 1.3 | 3.3 | 2.75 +/- 0.717 +/- 0.743 | 0.76 Note that FAP estimates (especially at timescales above 2s) may be further affected by enhanced non-stationary local background noise. This list excludes any excesses for which FAP is close to unity. All results quoted are preliminary. This circular is an official product of the INTEGRAL Multi-Messenger team. [1] Savchenko et al. 2017, A&A 603, A46 [2] Savchenko et al. 2012, A&A 541A, 122S GCN pipeline version: 88154a3 —————————————————————————— Alexis Coleiro Maître de conférences - Université Paris Diderot Laboratoire Astroparticule et Cosmologie (APC) 10 rue Alice Domon et Léonie Duquet 75205 Paris Cedex 13 (France) Tel.: +33 1 57 27 60 59 / coleiro@apc.univ-paris-diderot.fr //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26667 SUBJECT: IceCube-200107A: No candidates from the Zwicky Transient Facility DATE: 20/01/08 14:16:06 GMT FROM: Robert Stein at DESY Robert Stein and Simeon Reusch (DESY) report, 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-200107A (Stein et al., GCN 26655) with the Palomar 48-inch telescope, equipped with the 47 square degree ZTF camera (Bellm et al. 2019, Graham et al. 2019). We first started observations serendipitously in the g-band and r-band beginning at 2020-01-07T11:42:04.700 UTC, approximately 2.0 hours after event time. We covered 6.3 sq deg, corresponding to 84.2% 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) 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). We find no high-significance transient or variable candidates with our pipeline. We will continue to observe this field to search for new transients. ZTF and GROWTH are worldwide collaborations comprising Caltech, USA; IPAC, USA, WIS, Israel; OKC, Sweden; JSI/UMd, USA; U Washington, USA; DESY, Germany; MOST, Taiwan; UW Milwaukee, USA; LANL USA; Tokyo Tech, Japan; IITB, India; IIA, India; LJMU, UK; TTU, USA; SDSU, USA and USyd, Australia. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26668 SUBJECT: IceCube-200107A: No significant detection in HAWC DATE: 20/01/08 15:41:21 GMT FROM: Hugo Ayala at Pennsylvania State University Hugo Ayala (PSU) reports on behalf of the HAWC collaboration (http://www.hawc-observatory.org/collaboration): On 2020/01/07 09:42:18.36 UTC, the IceCube collaboration reported a track-like very-high-energy event that has a high probability of being an astrophysical neutrino, IceCube-200107A. Location is at RA: 148.18 (+2.20/-1.83 90% PSF containment) J2000 Dec: 35.46 (+1.10/-1.22 deg 90% PSF containment) J2000 https://gcn.gsfc.nasa.gov/gcn3/26655.gcn3 (GCN circular 26655). We performed two types of analyses for the follow-up. The first is for a steady source in archival data and the second is a search for a transient source. We assume a power-law spectrum with an index of -2.3 for both analyses. Search for a steady source in archival data: The archival data spans from November 2014 to May 2018. We searched inside the reported IceCube error region from the circular. The highest significance, 3.37 sigma (2.10 post-trials), is at RA 147.79 deg, Dec 34.68 deg (+-1.71 deg 68% containment) J2000. We set a time-integrated 95% CL upper limit on gamma rays at the maximum position of: E^2 dN/dE = 3.01439e-13 (E/TeV)^-0.3 TeV cm^-2 s^-1 Search for a transient source. Since the IceCube event fall inside the HAWC field of view, we report on the result for the current transit of the IceCube position. Data acquisition started on Data Start: 2020/01/07 06:02:39 UTC and ended 2020/01/07 12:24:01 UTC. The most significant location, with 2.16 sigma (-0.62 post-trials), is at RA 149.55 deg, Dec 34.68 deg (+-1.8 deg 68% containment) J2000. We set a time-integrated 95% CL upper limit at the position of maximum significance of: E^2 dN/dE = 4.10782e-12 (E/1TeV)^-0.3 TeV cm^-2 s^-1 HAWC is a very-high-energy gamma-ray observatory operating in Central Mexico at latitude 19 deg. north. Operating day and night with over 95% duty cycle, HAWC has an instantaneous field of view of 2 sr and surveys 2/3 of the sky every day. It is sensitive to gamma rays from 300 GeV to 100 TeV. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26669 SUBJECT: Fermi-LAT Gamma-ray Observations of IceCube-200107A DATE: 20/01/08 16:27:15 GMT FROM: Simone Garrappa at DESY S. Garrappa (DESY-Zeuthen) and S. Buson (Univ. of Wuerzburg) on behalf of the Fermi-LAT collaboration: We report an analysis of observations of the vicinity of the high-energy IC200107A neutrino event (GCN 26655) 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 2020-01-07 at 09:42:18.36 UT (T0) with J2000 position RA =148.18 (+ 2.20, - 1.83) deg, Decl. = 35.46 (+ 1.10, - 1.22) deg 90% PSF containment. Two cataloged >100 MeV gamma-ray sources (The Fermi-LAT Collaboration 2019, arXiv:1902.10045) are located within the 90% IC200107A localization error. These are the objects 4FGL J0955.1+3551 associated with the BL Lac object 1RXS J095508.2+355054 and 4FGL J0957.8+3423 associated with the blazar candidate object of uncertain type B2 0954+34. Based on a preliminary analysis of the LAT data over the timescales of 1-day and 1-month prior to T0, these objects are not significantly detected at gamma-rays. We searched for the existence of intermediate (months to years) timescale emission from a new gamma-ray transient source. Preliminary analysis indicates no significant (>5sigma) new excess emission (> 100 MeV) within the IC200107A 90% confidence localization. Assuming a power-law spectrum (photon index = 2.0 fixed) for a point source at the IceCube best-fit position, the >100 MeV flux upper limit (95% confidence) is < 1e-10 ph cm^-2 s^-1 for ~11-years (2008-08-04 / 2020-01-07 UTC), < 1e-8 (< 1e-7) 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 this source 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. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26691 SUBJECT: Swift follow-up observations of IceCube-200107A: Identification of X-ray high state for 4FGL J0955.1+3551 DATE: 20/01/09 19:51:46 GMT FROM: Derek B. Fox at Penn State F. Krauss, T. Gregoire, D.B. Fox, J. Kennea (PSU) and P. Evans (U. Leicester) report for AMON (https://amon.psu.edu/): "We have observed the positions of the two Fermi/LAT sources (Garrappa et al., GCN Circ. 26669), positionally coincident with the IceCube neutrino event IceCube-200107A (GCN Circ. 26655) with the Neil Gehrels Swift Observatory X-ray Telescope (XRT). We detect the blazar 4FGL J0955.1+3551 with an observed 2-10 keV flux of 4.7 (+/- 0.8) x 10^-12 erg cm-2 s-1 (2-10 keV). A spectrum constructed from these data can be well described by an absorbed power law with N_H = 5.3 x 10^20 cm-2 (wilm abundances, vern cross-sections), and a photon index of 1.8 (+0.23, -0.13). These data have also been reported in ATel #13394. This object has been previously observed by Swift/XRT, and its historical behavior can be seen in the 2SXPS catalogue (Evans et al., 2019): https://www.swift.ac.uk/2SXPS/2SXPS%20J095507.8%2B355100 Our recent observations are significantly brighter than the average flux in archival data: 1.78 (+0.14, -0.13) x 10-12 erg cm-2 s-1 (observed 2-10 keV flux), although the historical light curve does show that the source flux was gradually increasing in 2012 to 2013. The catalogued ROSAT flux of this source (as 1RXS J095508.2+355054) is 0.11 ct/sec which, assuming the above spectrum, corresponds to a 2-10 keV observed flux of ~1.9 x 10-12 erg cm-2 s-1; therefore we suggest that this source is currently in a high state. Further observations of this source are strongly recommended. The other source reported in GCN Circ. 26669 (4FGL J0957.8+3423) was not detected in our observations, with a 3-sigma upper limit of 0.010 ct/sec (0.3-10 keV). Assuming a standard spectrum (N_H = 3 x 10^20 cm-2, Gamma=1.7) this corresponds to a observed 2-10 keV flux upper limit of 2.7 x 10-13 erg cm-2 s-1. This source has not been previously covered by Swift/XRT observations." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26704 SUBJECT: IceCube-200107A: Upper limits from a search for additional neutrino events in IceCube DATE: 20/01/11 15:04:56 GMT FROM: Alex Pizzuto at ICECUBE/U of Wisconsin 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-200107A (https://gcn.gsfc.nasa.gov/gcn3/26655.gcn3) in a time range of 2 days centered on the alert event time (2020-01-06 09:42:18.36 UTC to 2020-01-08 09:42:18.36 UTC) during which IceCube was collecting good quality data. Excluding the event that prompted the alert, two additional track-like events are found in spatial coincidence with the 90% containment region of IceCube-200107A. We find that these data are consistent with atmospheric background expectations, with a p-value of 0.040. We accordingly derive a time-integrated muon-neutrino flux upper limit at the alert position of E^2 dN/ dE = 6.7 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 1 TeV and 500 TeV. A subsequent search was performed to include the month of data prior to the alert event (2019-12-08 09:42:18.36 UTC to 2020-01-08 09:42:18.36 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 9.8 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@icecube.wisc.edu.