//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 24716 SUBJECT: LIGO/Virgo S190602aq: Upper limits from IceCube neutrino searches DATE: 19/06/02 18:31:55 GMT FROM: Raamis Hussain at IceCube IceCube Collaboration (http://icecube.wisc.edu/) reports: Searches [1,2] for track-like muon neutrino events detected by IceCube consistent with the sky localization of gravitational-wave candidate S190602aq in a time range of 1000 seconds [3] centered on the alert event time (2019-06-02 17:51:07.089 UTC to 2019-06-02 18:07:47.089 UTC) have been performed. During this time period IceCube was collecting good quality data. No significant track-like events are found in spatial coincidence of S190602aq calculated from the map circulated in the 1-Preliminary notice. IceCube's sensitivity assuming an E^-2 spectrum (E^2 dN/dE)to neutrino point sources within the locations spanned by the 90% spatial containment of S190602aq ranges from 0.029 to 0.732 GeV cm^-2 in a 1000 second time window. 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] Bartos et al. arXiv:1810.11467 (2018) and Countryman et al.arXiv:1901.05486 (2019) [2] Braun et al., Astroparticle Physics 29, 299 (2008) [3] Baret et al., Astroparticle Physics 35, 1 (2011) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 24717 SUBJECT: LIGO/Virgo S190602aq: Identification of a GW compact binary merger candidate DATE: 19/06/02 18:36:06 GMT FROM: Peter Shawhan at U of Maryland/LSC The LIGO Scientific Collaboration and the Virgo Collaboration report: We identified the compact binary merger candidate S190602aq during real-time processing of data from LIGO Hanford Observatory (H1), LIGO Livingston Observatory (L1), and Virgo Observatory (V1) at 2019-06-02 17:59:27.089 UTC (GPS time: 1243533585.089). The candidate was found by the PyCBC Live [1], CWB [2], SPIIR [3], GstLAL [4], and MBTAOnline [5] analysis pipelines. S190602aq is an event of interest because its false alarm rate, as estimated by the online analysis, is 1.9e-09 Hz, or about one in 16 years. The event's properties can be found at this URL: https://gracedb.ligo.org/superevents/S190602aq The classification of the GW signal, in order of descending probability, is BBH (>99%), Terrestrial (<1%), BNS (<1%), NSBH (<1%), or MassGap (<1%). Assuming the candidate is astrophysical in origin, there is strong evidence against the lighter compact object having a mass < 3 solar masses (HasNS: <1%). Using the masses and spins inferred from the signal, there is strong evidence against matter outside the final compact object (HasRemnant: <1%). One skymap is available at this time and can be retrieved from the GraceDB event page: * bayestar.fits.gz, an updated localization generated by BAYESTAR [6], distributed via GCN notice about 6 minutes after the candidate For the bayestar.fits.gz skymap, the 90% credible region is 1172 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 797 +/- 238 Mpc (a posteriori mean +/- standard deviation). For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo Public Alerts User Guide . [1] Nitz et al. PRD 98, 024050 (2018) [2] Klimenko et al. PRD 93, 042004 (2016) [3] Qi Chu, PhD Thesis, The University of Western Australia (2017) [4] Messick et al. PRD 95, 042001 (2017) [5] Adams et al. CQG 33, 175012 (2016) [6] Singer & Price PRD 93, 024013 (2016) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 24718 SUBJECT: LIGO/Virgo S190602aq: No counterpart candidates in HAWC observations DATE: 19/06/02 18:37:52 GMT FROM: Israel Martinez-Castellanos at UMD/HAWC The HAWC Collaboration (https://www.hawc-observatory.org) reports: The HAWC Collaboration performed a follow-up of the gravitational wave trigger S190602aq. At the time of the trigger the HAWC local zenith was oriented towards (RA, Dec) = (63.2 deg, 18.9 deg). 57% of the GW candidate sky location probability fell within our observable field of view (0-45 deg zenith angle). We performed a search for a short timescale emission using 6 sliding time windows (dt = 0.3s, 1s, 3s, 10s, 30s and 100s), shifted forward in time by 20% of their width. We searched the 95% probability containment area in a timescale-dependent time period, from t0-5dt to t0+10dt, where t0 is the time of the GW trigger. No significant gamma-ray detection above the background was observed. The sensitivity of this analysis is greatly dependent on zenith angle, ranging from 14.4 deg to 45 deg for the area searched in this analysis. The 5sigma detection sensitivity to a 1s (100s) burst in the 80-800GeV energy range goes from 1.6e-6 erg/cm^2 to 1.1e-4 erg/cm^2 (8.6e-6 erg/cm^2 to 5.0e-4 erg/cm^2), depending on the zenith angle. HAWC is a TeV gamma ray water Cherenkov array located in the state of Puebla, Mexico. It is sensitive to the energy range ~0.1-100TeV, and monitors 2/3 of the sky every day with an instantaneous field-of-view of ~2 sr. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 24719 SUBJECT: LIGO/Virgo S190602aq: No neutrino counterpart candidates in ANTARES search DATE: 19/06/02 19:11:26 GMT FROM: Damien Dornic at CPPM,France M. Ageron (CPPM/CNRS), B. Baret (APC/CNRS), A. Coleiro (APC/Universite Paris Diderot), M. Colomer (APC/Universite Paris Diderot)), D. Dornic (CPPM/CNRS), A. Kouchner (APC/Universite Paris Diderot), T. Pradier (IPHC/Universite de Strasbourg) report on behalf of the ANTARES Collaboration: Using on-line data from the ANTARES detector, we have performed a follow-up analysis of the recently reported LIGO/Virgo S190602aq event using the 90% contour of the bayestar probability map provided by the GW interferometers (GCN#24717). The ANTARES visibility at the time of the alert, together with the 50% and 90% contours of the probability map are shown at https://www.cppm.in2p3.fr/~dornic/events_runo3/S190602aq.png. Considering the location probability provided by the LIGO/Virgo collaborations, there is a 84% chance that the GW emitter was in the ANTARES **upgoing** field of view at the time of the alert. No up-going muon neutrino candidate events were recorded in the ANTARES sky during a +/- 500s time-window centered on the time (2019-06-02 17:59:27 UT) and in the 90% contour of the S190602aq event. The expected number of atmospheric background events in the region visible by ANTARES is 6.8e-5 in the +/- 500s time window. An extended search during +/- 1 hour gives no up-going muon neutrino coincidence. The expected number of atmospheric background events in the region visible by ANTARES is 4.9e-4 in this larger time window. ANTARES is the largest undersea neutrino detector, installed in the Mediterranean Sea, and it is primarily sensitive to neutrinos in the TeV-PeV energy range. At 10 TeV, the median angular resolution for muon neutrinos is about 0.5 degrees. In the range 1-100 TeV ANTARES has a competitive sensitivity to this position in the sky. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 24720 SUBJECT: LIGO/Virgo S190602aq: Coverage and upper limits from MAXI/GSC observations DATE: 19/06/02 20:41:14 GMT FROM: Satoshi Sugita at Aoyama Gakuin U. M. Sugizaki, N. Kawai (Tokyo Tech), H. Negoro (Nihon U.), S. Sugita, M. Serino (AGU), M. Nakajima, W. Maruyama, M. Aoki, K. Kobayashi (Nihon U.), S. Nakahira, T. Mihara, T. Tamagawa, M. Matsuoka (RIKEN), T. Sakamoto, H. Nishida, A. Yoshida (AGU), Y. Tsuboi, W. Iwakiri, R. Sasaki, H. Kawai, T. Sato (Chuo U.), M. Shidatsu (Ehime U.), M. Oeda, K. Shiraishi (Tokyo Tech), S. Ueno, H. Tomida, M. Ishikawa, Y. Sugawara, N. Isobe, R. Shimomukai, M. Tominaga (JAXA), Y. Ueda, A. Tanimoto, S. Yamada, S. Ogawa, K. Setoguchi, T. Yoshitake (Kyoto U.), H. Tsunemi, T. Yoneyama, K. Asakura, S. Ide (Osaka U.), M. Yamauchi, S. Iwahori, Y. Kurihara, K. Kurogi, K. Miike (Miyazaki U.), T. Kawamuro (NAOJ), K. Yamaoka (Nagoya U.), Y. Kawakubo (LSU) report on behalf of the MAXI team: We examined MAXI/GSC all-sky X-ray images (2-20 keV) after the LVC trigger S190602aq at 2019-06-02 17:59:27.089 UTC (GCN 24717). At the trigger time of S190602aq, the high-voltage of MAXI/GSC was off, and it was turned on at T0+871 sec (+14.5 min). The first one-orbit (92 min) scan observation with GSC after the event covered 100% of the 90% credible region of the bayestar skymap from 19:02:18 to 19:22:28 UTC (T0+3771 to T0+4981 sec). No significant new source was found in the region in the one-orbit scan observation. A typical 1-sigma averaged upper limit obtained in one scan observation is 20 mCrab at 2-20 keV. If you require information about X-ray flux by MAXI/GSC at specific coordinates, please contact the submitter of this circular by email. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 24721 SUBJECT: LIGO/Virgo S190602aq Global MASTER-Net observations report DATE: 19/06/02 20:49:21 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 (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-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 LIGO/Virgo S190602aq errorbox 7805 sec after trigger time at 2019-06-02 20:09:32 UT, with upper limit up to 19.7 mag. The observations began at zenit distance = 135 deg. The sun altitude is -56.0 deg. The galactic latitude b = -60 deg., longitude l = 98 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/ligo_1.php?id=10444 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 7896 | 2019-06-02 20:09:32 | MASTER-SAAO | ( 11h 41m 04.89s , -53d 49m 46.57s) | C | 180 | 19.5 | 8113 | 2019-06-02 20:13:10 | MASTER-SAAO | ( 11h 35m 20.93s , -51d 49m 43.66s) | C | 180 | 19.7 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 24722 SUBJECT: LIGO/Virgo S190602aq: No counterpart candidate in AGILE-MCAL observations DATE: 19/06/02 21:22:56 GMT FROM: Claudio Casentini at INAF-IAPS C.Casentini (INAF/IAPS), F.Verrecchia (SSDC, and INAF/OAR), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), M.Cardillo, G.Piano, A.Ursi (INAF/IAPS), F.Lucarelli, C. Pittori (SSDC, and INAF/OAR), A. Bulgarelli, V. Fioretti, N. Parmiggiani (INAF/OAS-Bologna), M. Pilia (INAF/OA-Cagliari), F. Longo (Univ. Trieste, and INFN Trieste) report on behalf of the AGILE Team: In response to the LIGO/Virgo GW event S190602aq at T0 = 2019-06-02 17:59:27.089 (UT), a preliminary analysis of the AGILE minicalorimeter (MCAL) triggered data found no event candidate within a time interval covering +/- 15 sec from the LIGO/Virgo T0. Three-sigma upper limits (ULs) are obtained for a 1 s integration time at different celestial positions within the accessible 90% c.l. localization region (LR) of S190602aq (about 100% of the LR), from a minimum of 1.6E-06 erg cm^-2 to a maximum of 9.4E-06 erg cm^-2 (assuming as spectral model a single power law with photon index 1.5). The LR is exposed at off-axis angles greater than 100 deg. The AGILE-MCAL detector is a CsI detector with a 4 pi FoV, sensitive in the energy range 0.4-100 MeV. Additional analysis of AGILE data is in progress. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 24723 SUBJECT: LIGO/Virgo S190602aq: Upper limits from AGILE-GRID observations DATE: 19/06/02 23:37:01 GMT FROM: Francesco Verrecchia at ASDC F. Verrecchia (SSDC, and INAF-OAR), C. Casentini (INAF/IAPS), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), F. Lucarelli, C. Pittori (SSDC, and INAF-OAR), M. Cardillo, G. Piano A. Ursi (INAF/IAPS), A. Bulgarelli, V. Fioretti, N. Parmiggiani (INAF/OAS-Bologna), M. Pilia (INAF/OA-Cagliari), F. Longo (Univ. Trieste, and INFN Trieste), report on behalf of the AGILE Team: In response to the LIGO/Virgo GW event S190602aq at T0 = 2019-06-02 17:59:27.089 UTC (GCN #24717) a preliminary analysis of the AGILE exposure at T0 showed that the S190602aq 90% c.l. localization region (LR) was not exposed by the Gamma-Ray Imaging Detector (GRID). The closest exposure in time occurred at T0+100s covering about 100% of the LR at off-axis angles between 20 and 70 deg. We performed an analysis of the GRID data in the energy range 50 MeV - 10 GeV over a single time interval after T0, when good exposure of the S190602aq 90% c.l. LR was available. The following preliminary GRID 3-sigma upper limit (UL) values are obtained over a large area of the exposed LR: (T0+100s; T0+200s): from 3.0e-08 to 4.7e-07 erg cm^-2 s^-1 An image of the AGILE-GRID 100s exposure near T0 is available at the site https://tools.ssdc.asi.it/ImgView/Agile/S190602aq_T0+100s_d100s_FM_UL-E50la17 These measurements were obtained with AGILE observing a large portion of the sky in spinning mode. Additional analysis of AGILE data is in progress. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 24724 SUBJECT: LIGO/Virgo S190602aq: Upper limits from Fermi-GBM Observations DATE: 19/06/03 00:35:20 GMT FROM: Colleen A. Wilson at NASA/MSFC/NSSTC C.A. Wilson-Hodge and C. M. Hui (NASA/MSFC) report on behalf of the Fermi-GBM Team and the GBM-LIGO/Virgo group For S190602aq and using the initial bayestar.fits skymap, Fermi-GBM was observing 67.3% of the localization probability at event time. There was no Fermi-GBM onboard trigger around the event time of the LIGO/Virgo/ detection of GW trigger S190602aq (GCN 24717). 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 merger time, and also identified no counterpart candidates. Part of the LVC localization region is behind the Earth for Fermi, located at RA = 148.4 and Dec = -10.9 with a radius of 67.5 degrees. We therefore 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 ------------------------------------ 0.1 s:      4.3 7.5 17.0 1.0 s:      1.1 3.4 8.2 10  s:    0.27 0.63 1.7 Assuming the median luminosity distance of 797 Mpc from the GW detection, we estimate the following intrinsic luminosity upper limits over the 1 keV-10 MeV energy range (in units of 10^49 erg/s): Timescale  Soft Normal   Hard ------------------------------------ 0.1 s:     5.0          8.0 30.0     1.0 s:     1.3          3.6 14.5     10  s:   0.3 0.7 3.0  //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 24725 SUBJECT: LIGO/Virgo S190602aq: No counterpart candidates in the Swift/BAT Observations DATE: 19/06/03 01:35:33 GMT FROM: Amy Lien at GSFC A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (NASA/GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), A. A. Breeveld (MSSL-UCL), A. P. Beardmore (U. Leicester), D. N. Burrows (PSU), S. Campana (INAF-OAB), S. B. Cenko (NASA/GSFC), G. Cusumano (INAF-IASF PA), A. D'Ai (INAF-IASFPA), P. D'Avanzo (INAF-OAB), V. D'Elia(ASDC), S. Emery (UCL-MSSL), P. A. Evans (U. Leicester), P. Giommi (ASI), C. Gronwall (PSU), D. Hartmann (Clemson U.), J. A. Kennea (PSU), H. A. Krimm (NSF), N. P. M. Kuin (UCL-MSSL), F. E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB), J. A. Nousek (PSU), S. R. Oates (Uni. of Warwick), P. T. O'Brien (U. Leicester), J. P. Osborne (U. Leicester), C. Pagani (U. Leicester), K. L. Page (U.Leicester), M. Perri (ASDC), J. L. Racusin (NASA/GSFC), B. Sbarufatti (INAF-OAB/PSU), M. H. Siegel (PSU), G. Tagliaferri (INAF-OAB), A. Tohuvavohu (PSU), E. Troja (NASA/GSFC/UMCP) report on behalf of the Swift team: We report the search results in the BAT data within T0 +/- 100 s of the LVC event S190602aq (LIGO/VIRGO Collaboration GCN Circ. 24717), where T0 is the LVC trigger time (2019-06-02T17:59:27.089 UTC). The center of the BAT field of view (FOV) at T0 is RA = 212.203 deg, DEC = -45.287 deg, and the ROLL angle is 240.648 deg. The BAT FOV (>10% partial coding) covers 0.72% of the integrated LVC localization probability, and 0.67% of the galaxy convolved probability (Evans et al. 2016). Within T0 +/- 100 s, no significant detections (signal-to-noise ratio >~ 5 sigma) are found in the BAT raw light curves with time bins of 64 ms, 1 s, and 1.6 s. Assuming an on-axis (100% coded) short GRB with a typical spectrum in the BAT energy range (i.e., a simple power-law model with a power-law index of -1.32, Lien & Sakamoto et al. 2016), the 5-sigma upper limit in the 1-s binned light curve corresponds to a flux upper limit (15-350 keV) of ~ 8.42 x 10^-8 erg/s/cm^2. No event data are available within T0 +/- 100 s. BAT retains decreased, but significant, sensitivity to rate increases for gamma-ray events outside of its FOV. About 3.53% of the integrated LVC localization probability was outside of the BAT FOV but above the Earth's limb from Swift's location, and the corresponding flux upper limits for this region are within roughly an order of magnitude higher than those within the FOV. The results of the BAT analysis are available at https://swift.gsfc.nasa.gov/results/BATbursts/team_web/S190602aq/web/source.html //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 24726 SUBJECT: LIGO/Virgo S190602aq: No counterpart candidates in Fermi-LAT observations DATE: 19/06/03 05:18:44 GMT FROM: Magnus Axelsson at Stockholm U. M. Axelsson (KTH and Stockholm Univ.), D. Kocevski (NASA/MSFC) and F. Longo (Univ. and INFN Trieste) report on behalf of the Fermi-LAT Collaboration: We have searched data collected by the Fermi Large Area Telescope (LAT) on June 2, 2019, for possible high-energy (E > 100 MeV) gamma-ray emission in spatial/temporal coincidence with the LIGO/Virgo trigger S190602aq (GCN 24717). We define "instantaneous coverage" as the integral over the region of the LIGO probability map that is within the LAT field of view at a given a time, and "cumulative coverage" as the integral of the instantaneous coverage over time. At the time of the trigger (T0 = 2019-06-02 17:59:27.089 UTC) the entire LIGO probability region was either obscured by the Earth or outside the Fermi-LAT field of view. Coverage of the region started around T0 + 500 s, and reached ~90% cumulative coverage at approximately T0 + 8 ks. The remaining area was not observed within 10 ks after the trigger time. We performed a search for a transient counterpart within the observed region of the 90% contour of the LIGO map in a fixed time window from T0 + 500 s to T0+10 ks. No significant sources were found. We also performed a search which adapted the time interval of the analysis to the exposure of each region of the sky, and no additional excesses were found. Energy flux upper bounds for the fixed time interval between 100 MeV and 1 GeV for this search vary between 1.9e-10 and 9.1e-08 [erg/cm^2/s]. The Fermi-LAT point of contact for this event is Francesco Longo (francesco.longo@ts.infn.it). 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: 24727 SUBJECT: LIGO/Virgo S190602aq: upper limit in INTEGRAL SPI-ACS prompt observations DATE: 19/06/03 08:19:11 GMT FROM: Alexei Pozanenko at IKI, Moscow P. Minaev, A. Pozanenko, S. Grebenev, I. Chelovekov on behalf of IKI GRB FuN collaboration report: We used public data of SPI-ACS to perform a search for possible EM-counterpart of LIGO/Virgo S190602aq. Before and after trigger time of S190602aq we did not find any significant candidate (at the level more than 3 sigma) in time scales from 0.05 s up to 100 s. The angle between the center of the error box of the S190602aq localization by LIGO/Virgo and the SPI axis is 129 degrees, and the region of the LIGO probability is not occulted by the Earth. The 3 sigma upper limits in the energy range of 75 - 1000 keV are 1.2 * 10^-7 erg/cm2 (1 s time scale), and 1.2 * 10^-6 erg/cm2 (100 s time scale). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 24728 SUBJECT: LIGO/Virgo S190602aq: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation DATE: 19/06/03 08:50:54 GMT FROM: Francesca Onori at INAF/IAPS F. Onori (IAPS-Roma, Italy), 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 combination of INTEGRAL all-sky detectors (following Savchenko et al. 2017, A&A 603, A46): SPI/ACS, IBIS/Veto, and IBIS we have performed a search for a prompt gamma-ray counterpart of S190602aq (GCN 24717). At the time of the event (2019-06-02 17:59:27 UTC, hereafter T0), INTEGRAL was operating in nominal mode. The peak of the event localization probability was at an angle of 128 deg with respect to the spacecraft pointing axis. This orientation implies strongly suppressed (3.9% of optimal) response of ISGRI, somewhat suppressed (56% of optimal) response of IBIS/Veto, and strongly suppressed (29% 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 (as described in Savchenko et al. 2012, A&A 541A, 122S), IBIS, and IBIS/Veto data. We do not detect any significant counterparts and estimate a 3-sigma upper limit on the 75-2000 keV fluence of 3.8e-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 ~3.7e-07 (1.2e-07) erg/cm^2/s at 1 s (8 s) time scale in 75-2000 keV energy range. -- Dr. Francesca Onori Postdoctoral Researcher IAPS, via Fosso del Cavaliere, 100, 00133 - Rome, Italy e-mail: francesca.onori@inaf.it Tel: +39 06 45488128 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 24734 SUBJECT: LIGO/Virgo S190602aq: Upper limits from Insight-HXMT/HE observations DATE: 19/06/04 01:02:12 GMT FROM: QiBin Yi at IHEP, HXMT Q. B. Yi, S. Xiao, C. Cai, Q. Luo, C. K. Li, X. B. Li, G. Li, J. Y. Liao, S. L. Xiong, C. Z. Liu, X. F. Li, Z. W. Li, Z. Chang, A. M. Zhang, Y. F. Zhang, X. F. Lu, C. L. Zou (IHEP), Y. J. Jin, Z. Zhang (THU), T. P. Li (IHEP/THU), F. J. Lu, L. M. Song, M. Wu, Y. P. Xu, S. N. Zhang (IHEP), report on behalf of the Insight-HXMT team: Insight-HXMT was taking data normally around the reported LIGO/Virgo S190602aq event (GCN #24717), trigger time 2019-06-02T17:59:27.089 UTC. At T0, more than 54% of the LIGO localization region was covered by Insight-HXMT without occultation by the Earth. Within T0 +/- 100 s, no significant excess events (SNR > 3 sigma) are found in a search of the Insight-HXMT/HE raw light curves. Assuming the GW counterpart GRB with three typical GRB Band spectral models, two typical duration timescales (1 s, 10 s) from the center of the LIGO-Virgo location probability map (RA=80 deg, DEC=-40 deg), the 5-sigma upper-limits fluence (0.2 - 5 MeV, incident energy) are reported below: Band model 1 (alpha=-1.9, beta=-3.7, Ep=70 keV): 1 s: 5.6e-08 erg cm^-2 10 s: 1.4e-07 erg cm^-2 Band model 2 (alpha=-1.0, beta=-2.3, Ep=230 keV): 1 s: 1.1e-07 erg cm^-2 10 s: 2.6e-07 erg cm^-2 Band model 3 (alpha=-0.0, beta=-1.5, Ep=1000 keV): 1 s: 3.6e-07 erg cm^-2 10 s: 1.3e-06 erg cm^-2 All measurements above are made with the CsI detectors operating in the regular mode with the energy range of about 80-800 keV (deposited energy). Only gamma-rays with energy greater than about 200 keV can penetrate the spacecraft and leave signals in the CsI detectors installed inside of the spacecraft. Insight-HXMT is the first Chinese space X-ray telescope, which was funded jointly by the China National Space Administration (CNSA) and the Chinese Academy of Sciences (CAS). More information could be found at: http://www.hxmt.org. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 24735 SUBJECT: LIGO/Virgo S190602aq: Upper limits from CALET observations DATE: 19/06/04 03:25:42 GMT FROM: Yuta Kawakubo at Louisiana State U./CALET S. Torii (Waseda U), A. Yoshida, T. Sakamoto, V. Pal'shin, S. Sugita (AGU), Y. Kawakubo (LSU), K. Yamaoka (Nagoya U), S. Nakahira (RIKEN), Y. Asaoka, S. Ozawa (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U), N. Cannady (GSFC/UMBC), M. L. Cherry (LSU), S. Ricciarini (U of Florence), P. S. Marrocchesi (U of Siena), The CALET Gamma-ray Burst Monitor (CGBM) was operating at the trigger time of S190602aq T0 = 2019-06-02 17:59:27.089 UT (The LIGO Scientific Collaboration and Virgo Collaboration, GCN Circ. 24717). No CGBM on-board trigger occurred around the event time. Based on the LIGO-Virgo localization sky map, most of the high probability area was within the field-of-view of the CGBM SGM. The summed LIGO probabilities inside the CGBM HXM (7-3000 keV) and SGM (40 keV - 28 MeV) fields of view are 11% and 70%, respectively (and 99% credible region of the initial localization map was above the horizon). The HXM and SGM fields of view were centered at RA = 118.5 deg, Dec = 53.8 deg and RA = 127.2 deg, Dec = 45.5 deg at T0, respectively. Based on the analysis of the light curve data with 0.125 sec time resolution from T0-60 sec to T0+60 sec, we found no significant excess (signal-to-noise ratio >= 7) around the trigger time in either the HXM or the SGM data. The CALET Calorimeter (CAL) was operating in the high energy trigger mode at the trigger time of S190602aq. Using the CAL data, we have searched for gamma-ray events in the 10-100 GeV band from -60 sec to +60 sec from the GW trigger time and found no candidates. The 90% upper limit of CAL is 2.9x10^-4 erg/cm^2/s (10-100 GeV) when the summed LIGO-Virgo probability reaches 5%. The CAL FOV was centered at RA= 127.5 deg, DEC= 45.1 deg at T0. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 24736 SUBJECT: LIGO/Virgo S190602aq: AstroSat CZTI upper limits DATE: 19/06/04 05:19:48 GMT FROM: Varun Bhalerao at Indian Inst of Tech We have carried a search for X-ray candidates in Astrosat CZTI data in a 100 sec window around the trigger time of the BBH merger event S190602aq (UTC 2019-06-02 17:59:27.00, GraceDB event). CZTI is a coded aperture mask instrument that has considerable effective area for about 29% of the entire sky, but is also sensitive to brighter transients from the entire sky. At the time of merger, Astrosat's nominal pointing is (RA=295.71, DEC=-10.36), which is 134.4 deg away from the maximum probability location. In a time interval of 100 sec around the event, 51% of sky locations are visible in the satellite's frame and the rest of 49% with the inclusion of maximum probability location for the event are occulted by earth. CZTI data were de-trended to remove orbit-wise background variation. We then searched data from three of the four independent, identical quadrants to look for coincident spikes in the count rates. Searches were undertaken by binning the data in 0.1s, 1s, and 10s respectively. Statistical fluctuations in count rates were estimated by using data from 10 (+-5) neighbouring orbits. We selected confidence levels such that the probability of a false trigger in a 1000 sec window is 10^-4.We do not find any evidence for any hard X-ray transient in this window, in the CZTI energy range of 20-200 keV. We convert our count rates into flux by assuming that the source spectrum is a power law with alpha = -1.0. We use a detailed mass model of the satellite to calculate the instrument response for every htm grid point that fall in 90% LIGO localization region and calculate flux limit in that direction. We get the following upper limits for source flux in the 20-200 keV band by taking a probability weighted mean of flux limit and are reported here : 0.1 s: flux limit= 8.7 e-7 ergs/cm^2/s 1.0 s: flux limit= 3.0 e-6 ergs/cm^2/s 10.0 s: flux limit= 3.6 e-6 ergs/cm^2/s CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 24737 SUBJECT: S190602aq: MASTER OT detection DATE: 19/06/04 07:32:42 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, V.Kornilov, E.Gorbovskoy, N.Tiurina, A.Kuznetsov, I.Gorbunov, V.Vladimirov, P.Balanutsa, D.Vlasenko, D.Zimnukhov, F.Balakin,A. Chasovnikov, V.Topolev, V.Senik, D.Kuvshinov(Lomonosov Moscow State University, SAI, Physics Department), D. Buckley (South African Astronomical Observatory), R. Podesta, C. Lopez, C.Francile, F. Podesta (Observatorio Astronomico Felix Aguilar OAFA, San Juan National University), H.Levato (Instituto de Ciencias Astronomicas, de la Tierra y del Espacio ICATE, SJNU) R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres (The Instituto de Astrofisica de Canarias), O. Gress, N.M. Budnev, O.Ershova, S.Yazev (Applied Physics Institute, Irkutsk State University), V. Yurkov, A. Gabovich, Yu. Sergienko, D. Kobcev (Blagoveschensk Educational State University), A. Tlatov, D.Dormidontov, A.V. Parhomenko (Kislovodsk Solar Station of the Pulkovo Observatory), MASTER Global Robotic Net (Lipunov et al., 2010, Advances in Astronomy,vol.2010, 30L (http://observ.pereplet.ru) MASTER Global Robotic Net inspected S190602aq (Shawhan et al. GCN #24717, Lipunov et al. GCN #24721) and discovered optical transient (may be or not connected with BBH merging) MASTER OT J120315.71-525727.2 (ATel #12834; AT 2019gtv https://wis-tns.weizmann.ac.il/object/2019gtv) discovery- PSN in 1.1"E,6.3"S of PGC3074107 MASTER-OAFA auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) = 12h 3m 15.71s -52d 57m 27.20s on 2019-06-03 01:34:01UT. The OT unfiltered magnitude is m=16.9 (mlim=18.6m). The OT is seen in 2 inspect images. We reobserved it at MASTER-SAAO at 2019-06-03 16:39:45UT with m_OT=16.7. We have reference image without OT on 2019-04-24 22:43:07 UT with unfiltered mlim=18.6 m. This PSN is in 1.1"E,6.3"S of PGC3074107 (with unknown z, and magnitude http://leda.univ-lyon1.fr/ledacat.cgi?PGC3074107). Spectral observations are required. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/MASTEROTJ120315.71-525727.2.jpg