//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 27649 SUBJECT: IceCube Alert 200425.98: Global MASTER-Net observations report DATE: 20/04/26 00:13:21 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs 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), H.Levato (Instituto de Ciencias Astronomicas, de la Tierra y del Espacio ICATE), 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-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 IceCube Alert 200425.98 (trigger No 16038252,06h 42m 20.64s , +52d 38m 52.8s, R=0.95) errorbox 12 sec after notice time and 1171 sec after trigger time at 2020-04-25 23:46:17 UT, with upper limit up to 18.3 mag. The observations began at zenith distance = 81 deg. The sun altitude is -23.0 deg. MASTER-IAC robotic telescope located in Spain (IAC Teide Observatory) was pointed to the IceCube Alert 200425.98 errorbox 26 sec after notice time and 1185 sec after trigger time at 2020-04-25 23:46:32 UT, with upper limit up to 18.5 mag. The observations began at zenith distance = 71 deg. The sun altitude is -44.8 deg. The galactic latitude b = 20 deg., longitude l = 163 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1344471 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 1261 | 2020-04-25 23:46:17 | MASTER-Kislovodsk | (06h 42m 22.49s , +52d 57m 03.7s) | P| | 180 | 17.0 | 1261 | 2020-04-25 23:46:17 | MASTER-Kislovodsk | (06h 41m 56.14s , +52d 28m 56.6s) | P- | 180 | 16.9 | 1276 | 2020-04-25 23:46:32 | MASTER-IAC | (06h 40m 51.60s , +52d 37m 09.8s) | P| | 180 | 17.7 | 1456 | 2020-04-25 23:46:32 | MASTER-IAC | (06h 40m 51.60s , +52d 37m 09.8s) | P| | 540 | 18.5 | Coadd 1276 | 2020-04-25 23:46:32 | MASTER-IAC | (06h 39m 42.85s , +52d 41m 34.2s) | P- | 180 | 17.5 | 1456 | 2020-04-25 23:46:32 | MASTER-IAC | (06h 39m 42.85s , +52d 41m 34.2s) | P- | 540 | 18.4 | Coadd 1462 | 2020-04-25 23:49:38 | MASTER-Kislovodsk | (06h 42m 19.93s , +52d 58m 21.8s) | P| | 180 | 17.5 | 1462 | 2020-04-25 23:49:38 | MASTER-Kislovodsk | (06h 41m 53.58s , +52d 30m 15.3s) | P- | 180 | 17.5 | 1642 | 2020-04-25 23:49:38 | MASTER-Kislovodsk | (06h 41m 53.57s , +52d 30m 15.3s) | P- | 540 | 18.3 | Coadd 1512 | 2020-04-25 23:50:28 | MASTER-IAC | (06h 40m 57.74s , +52d 37m 04.9s) | P| | 180 | 18.0 | 1512 | 2020-04-25 23:50:28 | MASTER-IAC | (06h 39m 48.90s , +52d 41m 29.6s) | P- | 180 | 17.7 | 1663 | 2020-04-25 23:52:59 | MASTER-Kislovodsk | (06h 42m 20.41s , +52d 56m 42.2s) | P| | 180 | 17.6 | 1663 | 2020-04-25 23:52:59 | MASTER-Kislovodsk | (06h 41m 53.97s , +52d 28m 35.9s) | P- | 180 | 17.5 | 1754 | 2020-04-25 23:54:30 | MASTER-IAC | (06h 40m 53.95s , +52d 38m 50.7s) | P| | 180 | 18.1 | 1754 | 2020-04-25 23:54:30 | MASTER-IAC | (06h 39m 45.11s , +52d 43m 15.2s) | P- | 180 | 17.9 | 1864 | 2020-04-25 23:56:20 | MASTER-Kislovodsk | (06h 42m 23.82s , +52d 58m 06.8s) | P| | 180 | 17.7 | 1864 | 2020-04-25 23:56:20 | MASTER-Kislovodsk | (06h 41m 57.21s , +52d 29m 60.0s) | P- | 180 | 17.7 | 1995 | 2020-04-25 23:58:30 | MASTER-IAC | (06h 40m 54.07s , +52d 37m 27.0s) | P| | 180 | 18.1 | 1995 | 2020-04-25 23:58:30 | MASTER-IAC | (06h 39m 45.15s , +52d 41m 51.0s) | P- | 180 | 17.9 | The observation and reduction will continue. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 27651 SUBJECT: IceCube-200425A - IceCube observation of a high-energy neutrino candidate event DATE: 20/04/26 03:03:15 GMT FROM: Marcos Santander at U. Alabama/IceCube The IceCube Collaboration (http://icecube.wisc.edu/) reports: On 25 April, 2020 at 23:26:46.35 UT IceCube detected a track-like event with a moderate probability of being of astrophysical origin. The event was selected by the ICECUBE_Astrotrack_Bronze alert stream. The threshold astrophysical neutrino purity for Bronze alerts is 30%. This alert has an estimated false alarm rate of 0.5 events per year due to atmospheric backgrounds. The IceCube detector was in a normal operating state at the time of detection. After the initial automated alert (https://gcn.gsfc.nasa.gov/notices_amon_g_b/134013_16038252.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to: Date: 25 April 2020 Time: 23:26:46.35 UT RA: 100.10 (+4.67/-3.14 deg 90% PSF containment) J2000 Dec: 53.57 (+2.45/-1.60 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 no Fermi 4FGL or 3FHL catalog sources in the 90% uncertainty region. The nearest gamma-ray source in either catalog is 4FGL J0631.0+5626 at RA: 97.75 deg, Dec: 56.45 deg (3.18 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 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 27652 SUBJECT: IceCube-200425A: No counterpart candidates in INTEGRAL SPI-ACS prompt observation DATE: 20/04/26 07:43:15 GMT FROM: Diego Gotz at CEA D. Gotz (CEA-AIM, France), A. Lutovinov (IKI, Russia), V. Savchenko, C. Ferrigno (ISDC/UniGE, Switzerland), J. Rodi (IAPS-Roma, Italy) A. Coleiro (APC, France) 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-200425A (GCN 27651). At the time of the event (2020-04-25 23:26:46 UTC, hereafter T0), INTEGRAL was operating in nominal mode. The peak of the event localization probability was at an angle of 123 deg with respect to the spacecraft pointing axis. This orientation implies strongly suppressed (5.3% of optimal) response of ISGRI, strongly suppressed (36% of optimal) response of IBIS/Veto, and somewhat suppressed (61% of optimal) response of SPI-ACS. The background within +/-300 seconds around the event was very stable (excess variance 1.1). We have performed a search for any impulsive events in INTEGRAL SPI-ACS data (as described in [2]). 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 ~2.5e-07 (7.8e-08) 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: 7 likely background excesses: T-T0 | scale | S/N | flux ( x 1e-06 erg/cm2/s) | FAP 69.3 | 7 | 3.2 | 1.17 +/- 0.379 +/- 0.437 | 0.149 13.7 | 1 | 3.1 | 0.302 +/- 0.101 +/- 0.113 | 0.226 -2.22 | 0.15 | 3.1 | 0.772 +/- 0.261 +/- 0.289 | 0.272 -18.9 | 0.3 | 3.4 | 0.612 +/- 0.184 +/- 0.229 | 0.517 -264 | 2.5 | 3.5 | 2.13 +/- 0.635 +/- 0.799 | 0.708 -295 | 6.5 | 3.1 | 1.19 +/- 0.393 +/- 0.447 | 0.755 7.48 | 0.05 | 3.4 | 1.5 +/- 0.458 +/- 0.562 | 0.936 Note that FAP estimates (especially at timescales above 2s) may be possibly 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 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 27654 SUBJECT: Fermi-LAT Gamma-ray Observations of IceCube-200425A DATE: 20/04/27 14:15:46 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 IC200425A neutrino event (GCN 27651) 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 2020-04-25 23:26:46.35 UT (T0) with J2000 position RA = 100.10 (+4.67, -3.14) deg, Decl. = 53.57 (+2.45, -1.60) deg 90% PSF containment. No cataloged >100 MeV gamma-ray sources are located within the 90% IC200425A localization error. 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 IC200425A 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 < 4.6e-10 ph cm^-2 s^-1 for ~11-years (2008-08-04 / 2020-04-25 UTC), < 4.2e-9 (< 3.9e-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 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: 27655 SUBJECT: IceCube-200425A: Upper limits from Fermi-GBM Observations DATE: 20/04/27 16:31:54 GMT FROM: Cori Fletcher at USRA C. Fletcher (USRA) reports on behalf of the Fermi-GBM team: For the IceCube high-energy neutrino candidate event IceCube-200425A (GCN 27651), at the event time Fermi-GBM was observing the reported neutrino location at: RA: 100.10 (+4.67/-3.14 deg 90% PSF containment) J2000 Dec: 53.57 (+2.45/-1.60 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 identified a low reliability event 8.93 minutes before IceCube-200425A (https://gcn.gsfc.nasa.gov/notices_gbm_sub/609549478.fermi). However due to the temporal offset and low reliability, we do not consider these two events associated. 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-200425A. 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: 7.3 14. 37. 1.024 s: 2.6 3.9 10. 8.192 s: 0.8 1.8 3.5 These results are preliminary. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 27656 SUBJECT: IceCube-200425A: Upper limits from a search for additional neutrino events in IceCube DATE: 20/04/27 17:18:46 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-200425A (https://gcn.gsfc.nasa.gov/gcn3/27651.gcn3) in a time range of 2 days centered on the alert event time (2020-04-24 23:26:46.340 UTC to 2020-04-26 23:26:46.340 UTC) during which IceCube was collecting good quality data. Excluding the event that prompted the alert, four additional track-like events are found in spatial coincidence with the 90% containment region of IceCube-200425A. We find that these data are consistent with atmospheric background expectations, with a p-value of 0.077. We accordingly derive a time-integrated muon-neutrino flux upper limit at the alert position of E^2 dN/ dE = 7.5 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 1 TeV and 200 TeV. A subsequent search was performed to include the month of data prior to the alert event (2020-03-26 23:26:46.340 UTC to 2020-04-26 23:26:46.340 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 1.5 x 10^-4 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. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 27658 SUBJECT: IceCube-200425A: No significant detection in HAWC DATE: 20/04/27 20:43:58 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 2020/04/25 23:26:46 UTC, the IceCube collaboration reported a track-like very-high-energy event that has a high probability of being an astrophysical neutrino, IceCube-YYMMDDA. Location is at RA: 100.10 (+4.67/-3.14 deg 90% PSF containment) J2000 Dec: 53.57 (+2.45/-1.60 deg 90% PSF containment) J2000 (GCN circular 27651). 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. The highest significance, 2.57 sigma (-0.15 sigma post-trials), is at RA 101.11 deg, Dec +55.25 deg (±0.243 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 = 7.8e-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 2020/04/25 01:10:47 UTC and ended 2020/04/26 01:32:24 UTC. The most significant location, with 1.92 sigma (-2.28 sigma post-trials), is at RA 96.94 deg, Dec +54.15 deg (±0.633 deg 68% containment) J2000. We set a time-integrated 95% CL upper limit at the position of maximum significance of: E^2 dN/dE = 6.8e-12 (E/TeV)^-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.