//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26454 SUBJECT: LIGO/Virgo S191216ap: Identification of a GW compact binary merger candidate DATE: 19/12/16 22:03:55 GMT FROM: Brandon Piotrzkowski at U of Wisconsin-Milwaukee The LIGO Scientific Collaboration and the Virgo Collaboration report: We identified the compact binary merger candidate S191216ap during real-time processing of data from LIGO Hanford Observatory (H1) and Virgo Observatory (V1) at 2019-12-16 21:33:38.473 UTC (GPS time: 1260567236.473). The candidate was found by the GstLAL [1], MBTAOnline [2], and PyCBC Live [3] analysis pipelines. S191216ap is an event of interest because its false alarm rate, as estimated by the online analysis, is 1.1e-23 Hz, or about one in 1e15 years. The event's properties can be found at this URL: https://gracedb.ligo.org/superevents/S191216ap The classification of the GW signal, in order of descending probability, is MassGap (>99%), Terrestrial (<1%), BNS (<1%), BBH (<1%), or NSBH (<1%). Assuming the candidate is astrophysical in origin, the probability that the lighter compact object has a mass < 3 solar masses (HasNS) is 19%. Using the masses and spins inferred from the signal, the probability of matter outside the final compact object (HasRemnant) is <1%. One sky map is available at this time and can be retrieved from the GraceDB event page: * bayestar.fits.gz,0, an initial localization generated by BAYESTAR [4], distributed via GCN notice about 16 minutes after the candidate event time. For the bayestar.fits.gz,0 sky map, the 90% credible region is 300 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 324 +/- 78 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] Messick et al. PRD 95, 042001 (2017) [2] Adams et al. CQG 33, 175012 (2016) [3] Nitz et al. PRD 98, 024050 (2018) [4] Singer & Price PRD 93, 024013 (2016) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26455 SUBJECT: LIGO/Virgo S191216ap: No counterpart candidates in HAWC observations DATE: 19/12/16 22:27:09 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 S191216ap (GCN #26454). At the time of the trigger the HAWC local zenith was oriented towards (RA, Dec) = (311.1deg, 18.9deg). 99% 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 0 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 1.2e-6 erg/cm^2 to 1.1e-4 erg/cm^2 (6.8e-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: 26456 SUBJECT: LIGO/Virgo S191216ap: no INTEGRAL observation DATE: 19/12/16 22:27:22 GMT FROM: Diego Gotz at CEA D. Gotz (AIM/DAp CEA Saclay, France), A. Lutovinov (IKI, Russia) V. Savchenko, C. Ferrigno (ISDC/UniGE, Switzerland) S. Mereghetti (INAF IASF-Milano, Italy) A. Coleiro (APC, France) on behalf of the INTEGRAL multi-messenger collaboration report: https://www.astro.unige.ch/cdci/integral-multimessenger-collaboration At the time of LIGO/Virgo S191216ap event (GCN 26454) INTEGRAL was at its perigee, and its instruments were turned off. No INTEGRAL coverage is thus available for LIGO/Virgo S191216ap. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26457 SUBJECT: LIGO/Virgo S191216ap: Global MASTER-Net observations report DATE: 19/12/16 22:27:35 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-Tunka robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Applied Physics Institute, Irkutsk State University) started inspect of the LIGO/Virgo S191216ap errorbox 1752 sec after notice time and 2831 sec after trigger time at 2019-12-16 22:20:49 UT, with upper limit up to 17.1 mag. The observations began at zenith distance = 61 deg. The sun altitude is -24.3 deg. The galactic latitude b = -12 deg., longitude l = 77 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/ligo_1.php?id=11063 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 2862 | 2019-12-16 22:20:49 | MASTER-Tunka | (19h 00m 03.48s , +57d 38m 43.8s) | C | 60 | 17.1 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26458 SUBJECT: LIGO/Virgo S191216ap : no neutrino counterpart candidate in ANTARES search DATE: 19/12/16 22:57:22 GMT FROM: Thierry Pradier at ANTARES/IPHC/U of Strasbourg M. Ageron (CPPM/CNRS), B. Baret (APC/CNRS), A. Coleiro (APC/Universite de Paris), M. Colomer (APC/Universite de Paris), D. Dornic (CPPM/CNRS), A. Kouchner (APC/Universite de Paris), 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 S191216ap event using the 90% contour of the Initial bayestar probability map provided by the GW interferometers (GCN#26454 ). The ANTARES visibility at the time of the alert, together with the 50% and 90% contours of the probability map are shown at http://antares.in2p3.fr/GW/S191216ap_Initial.png . Considering the location probability provided by the LIGO/Virgo collaborations, there is a 15.9% 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 2019-12-16 21:33:38 and in the 90% contour of the S191216ap event. The expected number of atmospheric background events in the region visible by ANTARES is 6.52e-05 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 overlapping with the 90% contour is 4.70e-04 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: 26460 SUBJECT: LIGO/Virgo S191216ap: 1 counterpart neutrino candidate from IceCube neutrino searches DATE: 19/12/16 23:52:37 GMT FROM: Raamis Hussain at IceCube IceCube Collaboration (http://icecube.wisc.edu/) reports: Searches for track-like muon neutrino events detected by IceCube consistent with the sky localization of gravitational-wave candidate S191216ap in a time range of 1000 seconds [1] centered on the alert event time (21:25:18.473 UTC to 21:41:58.473 UTC) have been performed. Up until 21:33:21 UTC IceCube was collecting good quality data, at which point power issues at the experimental site caused issues with data quality. Only neutrino candidates collected before this time are considered. Two hypothesis tests were conducted. The first search is a maximum likelihood analysis which searches for a generic point-like neutrino source coincident with the given GW skymap [2]. The second uses a Bayesian approach to quantify the joint GW + neutrino event significance, which assumes a binary merger scenario and accounts for known astrophysical priors in the significance estimate, such as GW source distance [3]. 1 track-like event is found in spatial and temporal coincidence with the gravitational-wave Candidate S191216ap calculated from the map circulated in the 2-Initial notice. This represents an overall p-value of 0.104 (1.26 sigma) from the generic transient search and an overall p-value of 0.0059 (2.52 sigma) for the Bayesian search. These p-values measure the consistency of the observed track-like events with the known atmospheric backgrounds. Both analyses assume 100% livetime during the search window; the statistical significances are therefore lower limits. The reported p-values can differ due to the estimated distance of the GW candidate. The distance is used as a prior in Bayesian binary merger search, while it is not taken into account in the generic transient point-like source search. Properties of the coincident event are shown below. dt ra(deg) dec(deg) Angular Uncertainty(deg) p-value(generic transient) p-value(binary merger) -------------------------------------------------------------------------------------------------------------------- -43s 329.19 4.53 4.07 0.219 0.0059 where: dt = Time offset (sec) of track event with respect to GW trigger. Angular uncertainty = Angular uncertainty of track event: the radius of a circle representing 90% CL containment by area. Pvalue = the pvalue for this specific track event from each search. 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] Baret et al., Astroparticle Physics 35, 1 (2011) [2] PoS(ICRC2019)918, Braun et al., Astroparticle Physics 29, 299 (2008) [3] Bartos et al. arXiv:1810.11467 (2018) and Countryman et al.arXiv:1901.05486 (2019) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26461 SUBJECT: LIGO/Virgo S191216ap: Upper limits from Fermi-GBM Observations DATE: 19/12/17 02:19:46 GMT FROM: Joshua Wood at MSFC/Fermi-GBM J. Wood (NASA/MSFC) reports on behalf of the Fermi-GBM Team and the GBM-LIGO/Virgo group For S191216ap and using the initial bayestar.fits.gz skymap, Fermi-GBM was observing 99.8% 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 S191216ap (GCN 26454). 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. 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, weighted by GW localization probability (in units of 10^-7 erg/s/cm^2): Timescale Soft Normal Hard ------------------------------------ 0.128 s: 5.7 8.5 16. 1.024 s: 2.1 3.6 5.7 8.192 s: 0.7 1.0 2.0 Assuming the median luminosity distance of 324 Mpc from the GW detection, we estimate the following intrinsic luminosity upper limits over the 1 keV-10 MeV energy range (in units of 10^48 erg/s): Timescale Soft Normal Hard ------------------------------------ 0.128s: 11. 15. 47. 1.024s: 4.0 6.4 17. 8.192s: 1.4 1.8 5.9 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26462 SUBJECT: LIGO/Virgo S191216ap: Coverage and upper limits from MAXI/GSC observations DATE: 19/12/17 04:18:22 GMT FROM: Hitoshi Negoro at Nihon U H. Negoro (Nihon U.), N. Kawai (Tokyo Tech), S. Sugita, M. Serino (AGU), M. Nakajima, W. Maruyama, M. Aoki, K. Kobayashi, R. Takagi (Nihon U.), T. Mihara, C. Guo, Y. Zhou, 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. Nakahira, Y. Sugawara, S. Ueno, H. Tomida, M. Ishikawa, 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), M. Sugizaki (NAOC) report on behalf of the MAXI team: We examined MAXI/GSC all-sky X-ray images (2-20 keV) after the LVC trigger S191216ap at 2019-12-16 21:33:38.473 UTC (GCN 26454). At the trigger time of S191216ap, the high-voltage of MAXI/GSC was on, but the FOV was out of the 90% credible region of the bayestar skymap. The first one-orbit (92 min) scan observation with GSC after the event covered 97% of the 90% credible region of the bayestar skymap from 21:34:38 to 22:13:47 UTC (T0+60 to T0+2409 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: 26463 SUBJECT: LIGO/Virgo S191216ap: Correction to GCN 26460 (IceCube event coincident with GW event) DATE: 19/12/17 05:21:02 GMT FROM: Raamis Hussain at IceCube The coordinates of the candidate neutrino event coincident with LIGO/Virgo S191216ap circulated in the original GCN circular 26460 ( https://gcn.gsfc.nasa.gov/gcn3/26460.gcn3) contained an error. The correct right ascension value is given in the table below: dt ra(deg) dec(deg) 90% Angular Uncertainty(deg) p-value(generic transient) p-value(binary merger) -------------------------------------------------------------------------------------------------------------------- -43s 323.19 4.53 4.07 0.219 0.0059 We sincerely apologize for the inconvenience this may have caused to follow-up observers. The IceCube realtime alert point of contact can be reached at roc@icecube.wisc.edu //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26464 SUBJECT: LIGO/Virgo S191216ap: No Candidates from the Zwicky Transient Facility DATE: 19/12/17 05:27:12 GMT FROM: Shreya Anand at GROWTH Caltech Shreya Anand (Caltech), Tomas Ahumada (UMD), Eric Bellm (UW), S. Bradley Cenko (NASA/GSFC), Michael Coughlin (Caltech), Dougal Dobie (USyd/CSIRO), Daniel Goldstein (Caltech), Albert Kong (NTHU), Harsh Kumar (IIT-B) Leo Singer (NASA/GSFC), Igor Andreoni (Caltech), David Kaplan (UWM), and Mansi M. Kasliwal (Caltech) 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 gravitational wave trigger S191216ap (LVC, GCN #26454) with the Palomar 48-inch telescope equipped with the 47 square degree Zwicky Transient Facility camera (ZTF, Bellm et al. 2019, Graham et al. 2019). The tiling was optimally determined and triggered using the GROWTH Target of Opportunity marshal (Coughlin et al. 2019a, Kasliwal et al. 2019b). We started obtaining target-of-opportunity observations in the g-band and r-band beginning at 2019-12-17 01:47 UT, covering 86% of the integrated probability based on the BAYESTAR skymap (LVC, GCN #26454). Each exposure was 300s, reaching a g-band median depth of 19.8 mag and r-band median depth of 18.5 mag. Due to the severe weather constraints at Palomar we were unable to acquire deeper images. 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). Alert filtering and follow-up coordination was undertaken by the GROWTH Marshal system (Kasliwal et al. 2019). The ZTF alert stream was also queried using the Kowalski infrastructure (Duev et al., 2019). We required at least 2 detections with RB scores greater than 0.15 (Duev et al. 2019) separated by at least 30 minutes to reject artifacts and moving objects. Thus far, no candidate counterparts were identified by our pipeline in the observed area. Further analysis is in progress. ZTF and GROWTH are worldwide collaborations comprising of 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. ZTF acknowledges the generous support of the NSF under AST MSIP Grant No 1440341. GROWTH acknowledges generous support of the NSF under PIRE Grant No 1545949. Alert distribution service provided by DIRAC@UW (Patterson et al. 2019). Alert filtering and follow-up coordination is being undertaken by the GROWTH marshal system (Kasliwal et al. 2019). Alert database searches are done with using the Kowalski infrastructure (Duev et al., 2019). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26466 SUBJECT: LIGO/Virgo S191216ap: no counterpart candidates in the Swift/BAT observations DATE: 19/12/17 06:34:19 GMT FROM: Amy Lien at GSFC D. M. Palmer (LANL), S. D. Barthelmy (NASA/GSFC), A. Y. Lien (GSFC/UMBC), T. Sakamoto (AGU), A. P. Beardmore (U. Leicester), M. G. Bernardini (INAF-OAB), A. A. Breeveld (MSSL-UCL), 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 (ASI-ASDC), S. Emery (UCL-MSSL), P. A. Evans (U. Leicester), P. Giommi (ASI), C. Gronwall (PSU), D. Hartmann (Clemson U.), J. A. Kennea (PSU), N. Klingler (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. J. Page (UCL-MSSL), M. Perri (ASDC), J. L. Racusin (NASA/GSFC), B. Sbarufatti (INAF-OAB/PSU), M. H. Siegel (PSU), G. Tagliaferri (INAF-OAB), A. Tohuvavohu (U. Toronto), 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 S191216ap (LIGO/VIRGO Collaboration GCN Circ. 26454), where T0 is the LVC trigger time (2019-12-16T21:33:38.472 UTC). The center of the BAT field of view (FOV) at T0 is RA = 223.083 deg, DEC = 20.198 deg, and the roll angle is 133.749 deg. The BAT FOV (>10% partial coding) covers 0.20% of the integrated LVC localization probability, and 0.24% of the galaxy convolved probability (Evans et al. 2016). Note that the sensitivity in the BAT FOV changes with the partial coding fraction. Please see the BAT FOV figure in the summary page (link below) for the specific location of the LVC region relative to the BAT FOV. 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 ~ 5.13 x 10^-8 erg/s/cm^2. Assuming a luminosity of ~ 2 x 10^47 erg/s (similar to GW170817) and an average Epeak of ~ 400 keV for short GRBs (Bhat et al. 2016), this flux upper limit corresponds to a distance of ~ 100.31 Mpc. Event data are available from T0-44.64 s to T0+45.42 s, and T0+78.36 to T0+88.42 s. No significant detections (above our typical image threshold of ~ 6.5 to 7 sigma) are found in the 15-350 keV images created using intervals of T0-0.1 to T0+0.1 s, T0-2 s to T0+8 s, and the whole event data range. BAT retains decreased, but significant, sensitivity to rate increases for gamma-ray events outside of its FOV. About 99.72% 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/S191216ap/web/source_public.html //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26472 SUBJECT: LIGO/Virgo S191216ap: HAWC gamma-ray sub-threshold event coincident with LIGO/Virgo and IceCube localizations DATE: 19/12/17 13:54:23 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 S191216ap, reported in GCN Circular 26455. We did not report a significant detection after considering the trials incurred by looking at the whole gravitational wave localization contour. We however found that the most significant sub-threshold event is coincident with the (corrected) localization of a neutrino event reported by IceCube in GCN Circular 26463 (RA: 323.19 deg, Dec: 4.53 deg, 90% cont.: 4.07 deg). The HAWC event coordinates are: RA (J2000): 323.53 deg Dec (J2000): 5.23 deg 68% cont.: 0.30 deg Significance: 4.6 sigma (pre-trials) This event was found in the 10 s search, starting at 1260567316.47 GPSs (80.0 s after the time of coalescence). We encourage follow-up observations of this location. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26473 SUBJECT: LIGO/Virgo S191216ap: No significant counterpart candidates in SAGUARO observations DATE: 19/12/17 14:13:53 GMT FROM: Michael J. Lundquist at University of Arizona Michael J. Lundquist, David J. Sand (UA), Wen-fai Fong, Jillian Rastinejad, Kerry Paterson (Northwestern), Jennifer Andrews (UA), Sam Wyatt (UA), Eric Christensen, Alex Gibbs, Frank Shelly, report on behalf of the SAGUARO collaboration: We initiated observations of 24 fields (each 5 deg^2, totalling 120 deg^2) within the LVC localization region for the GW trigger S191216ap (LVC Circ 26454) starting on 2019-12-17 at 1:25 UT (3.9 hours after the GW trigger) with the 1.5m Catalina Sky Survey (CSS) telescope on Mt. Lemmon, AZ. Below are the field centers observed. RA Dec 321.5850 1.10417 321.3495 3.3125 321.3495 5.52081 321.1110 7.72917 321.1110 9.93747 320.8695 12.1458 323.1060 12.1458 320.3775 14.3541 322.6410 14.3541 320.1255 16.5625 322.4055 16.5625 321.9225 18.7708 319.6155 18.7708 321.4290 20.9792 319.0905 20.9792 320.9205 23.1875 318.5520 23.1875 320.1330 25.3958 317.7180 25.3958 319.3155 27.6042 316.8495 27.6042 318.4605 29.8125 317.5710 32.0208 316.6425 34.2291 Overall image quality was poor. We perform real-time processing and image subtraction (described in Lundquist et al. 2019, ApJL, 881, 2). After discarding known moving objects, stellar sources and known transients (cross-correlating with the Transient Name Server and the ZTF alert stream), we find no significant candidates with S/N>5, although a more detailed analysis is ongoing. We have posted our pointings to the Treasure Map, and encourage others to do the same: http://treasuremap.space/alerts?graceids=S191216ap SAGUARO is supported by the National Science Foundation under Award Nos. AST-1909358 and AST-1908972. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26474 SUBJECT: LIGO/Virgo S191216ap: IceCube event: MASTER OF detection in GW and Neutrino error field DATE: 19/12/17 14:14:26 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), 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) 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), During a MASTER-net inspect of LIGO/Virgo S191216ap (Lipunov et al., GCN 26457) MASTER-Amur robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Blagoveshchensk State Pedagogical University) started inspect of the LIGO/Virgo S191216ap IceCube neutrino counterpart errorbox (GCN 26460,26463) 41727 sec after trigger time at 2019-12-17 09:17:25 UT, with upper limit up to 17.4 mag. Observations started at twilight. The observations began at zenith distance = 50 deg. The sun altitude is -16.2 deg. MASTER-Tunka robotic telescope located in Russia (Applied Physics Institute, Irkutsk State University) started inspect of the LIGO/Virgo S191216ap IceCube neutrino counterpart errorbox 44823 sec after trigger time at 2019-12-17 10:09:01 UT, with upper limit up to 19.0 mag. Observations started at twilight. The observations began at zenith distance = 50 deg. The sun altitude is -10.0 deg. MASTER OF J212806.11+023221.9s - Optical Flare known CV. MASTER-Tunka auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OF at (RA, Dec) = 21h 28m 06.11s +02d 32m 21.9s on 2019-12-17.43984 UT. This flash falls off with the position of the famous CV CSS 151110: 212806 + 023221 (U Gem type). The OT magnitude in 'C' filter is 17.0m (mlim18.3=). The OT is seen in 2 images. There is no minor planet at this place. We have reference image on 2010-08-29.64730 UT with unfiltered mlim= 18.8m. Spectral observations are required. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1228593 The observation and reduction will continue. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26475 SUBJECT: LIGO/Virgo S191216ap and IceCube neutrino: Swift XRT sources DATE: 19/12/17 15:03:57 GMT FROM: Phil Evans at U of Leicester P.A. Evans (U. Leicester), A. Keivani (Colombia U.), J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto), S. Countryman (Colombia U.), I. Bartos (U. Florida), D. Fox (PSU), S. Marka (Colombia U.), Zsuzsa Marka (Colombia U.) S.D. Barthelmy (NASA/GSFC), A.P. Beardmore (U. Leicester), M.G. Bernardini (INAF-OAB), A.A. Breeveld (UCL-MSSL), P. Brown (TAMU), 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.W.K. Emery (UCL-MSSL), P. Giommi (ASI), C. Gronwall (PSU), D. Hartmann (U. Clemson), H.A. Krimm (CRESST/GSFC/USRA), N.J. Klingler (PSU), N.P.M. Kuin (UCL-MSSL), A.Y. Lien (GSFC/UMBC), F.E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB), J.A. Nousek (PSU), S.R. Oates (U. Birmingham), P.T. O'Brien (U. Leicester), J.P. Osborne (U. Leicester), C. Pagani (U. Leicester), K.L. Page (U.Leicester), M.J.Page (UCL-MSSL), D.M. Palmer (LANL), M. Perri (ASDC), J.L. Racusin (NASA/GSFC), B. Sbarufatti (INAF-OAB/PSU), M.H. Siegel (PSU), G. Tagliaferri (INAF-OAB), E. Troja (NASA/GSFC/UMCP) report on behalf of the Swift team: Swift has carried out 100 observations of the overlap between the LVC (GCN Circ. 26454) and IceCube (GCN Circ. 26463) error regions for the GW trigger S191216ap. The observations span from 22 ks to 42 ks after the LVC trigger, and the XRT has covered 10.2 deg^2 on the sky (corrected for overlaps). This covers 3.3% of the probability in the bayestar skymap, and 5.8% after convolving with the 2MPZ galaxy catalogue, as described by Evans et al. (2016, MNRAS, 462, 1591). It covers 65% of the probability contained within the combined GW and neutrino localisations. These pointings and associated metadata have been reported to the Treasure Map (Wyatt et al., GCN Circ. 26244; http://treasuremap.space/alerts?graceids=S191216ap). We have detected 3 X-ray sources. Each source is assigned a rank of 1-4 which describes how likely it is to be related to the GW trigger, with 1 being the most likely and 4 being the least likely. The ranks are described at https://www.swift.ac.uk/ranks.php. We have found: * 0 sources of rank 1 * 0 sources of rank 2 * 1 source of rank 3 * 2 sources of rank 4 For all flux conversions and comparisons with catalogues and upper limits from other missions, we assumed a power-law spectrum with NH=3x10^20 cm^-2, and photon index (Gamma)=1.7 The results of the XRT automated analysis are online at https://www.swift.ac.uk/LVC/S191216ap This circular is an official product of the Swift XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26476 SUBJECT: LIGO/Virgo S191216ap: galaxies consistent with GW + Neutrino + HAWC position DATE: 19/12/17 16:19:32 GMT FROM: Varun Bhalerao at Indian Inst of Tech H. Kumar (IITB), A. Sagués Carracedo (OKC, Stockholm University), T. Ahumada (UMD), I. Andreoni (Caltech), V. Bhalerao (IITB) report on behalf of the GROWTH collaboration: We cross-matched the HAWC trigger position (HAWC Collaboration, GCN 26472) with the GLADE catalog (Dalya et al., 2018), to identify sources within 0.9 degrees (approximately 3-sigma) of the HAWC position RA, Dec = 323.53, 5.23. We further applied a distance constraint based on the 3D Bayestar localisation provided by the LVC (bayestar.fits.gz,1), using mean distance = 95.6 Mpc and distance sigma = 37.4 Mpc, appropriate for this direction. We find four objects in GLADE 1 (http://vizier.u-strasbg.fr/viz-bin/VizieR-3?-source=VII/275/glade1) that are consistent with the position and distance at 3-sigma: ra dec sep dist sigma 323.124298 5.346313 0.42 85.3405 1.43 323.741486 5.792747 0.601 150.166 2.48 323.621368 6.034144 0.809 85.5611 2.71 323.298126 4.682521 0.594 173.891 2.88 (sep = separation in degrees). If we use the newer Glade 2.3 catalog (https://vizier.u-strasbg.fr/viz-bin/VizieR?-source=VII/281), we find only the first two objects as consistent within 3-sigma. Further observations of these galaxies are under way. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26478 SUBJECT: LIGO/Virgo S191216ap: Nanshan follow-up observations DATE: 19/12/17 18:14:17 GMT FROM: Dong Xu at NAOC/CAS D. Xu, Z.P. Zhu, H.J. Wang, L. Ge, T.M. Zhang, X. Zhou, C.Z. Cui, Y.F. Xu (NAOC), X. Zhang, J.Z. Liu (XAO), H.B. Zhao, B. Li (PMO), J.R. Mao (YNAO), X. Gao (Urumqi No.1 Senior High School) report on behalf of the GWFUNC collaboration: We observed the localization regions of the LIGO/Virgo gravitational wave trigger S191216ap (GCN #26454), the IceCube neutrino counterpart candidate (GCN #26460), and the HAWC gamma-ray counterpart candidate (GCN #26472), using the Nanshan 1-meter telescope with the FOV of 1.3x1.3 deg^2. Observations started at 11:57:05 UT and ended at 15:19:31 UT on 2019-12-17. Our survey area covers No.1 (ra: 323.124298, dec: 5.346313) and No.4 (ra: 323.298126, dec: 4.682521) GLADE galaxies, reported in Kumar et al. (GCN #26476). No 1. galaxy has m(r) ~ 15.67 mag in our image, being consistent with m(r) = 15.60 mag in SDSS. No. 4 galaxy has m(r) ~ 17.02 mag in our image, being consistent with m(r) = 16.99 mag in SDSS. Any significant optical transient within these two galaxies can be ruled out. Full data analysis of the searching is ongoing. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26479 SUBJECT: LIGO/Virgo S191216ap: CORRECTED list of galaxies coincident with LIGO/Virgo and HAWC positions DATE: 19/12/17 19:10:25 GMT FROM: Leo Singer at GSFC L. Singer (GSFC), T. Ahumada (UMD), S. Anand (Caltech), J. S. Bloom (UCB), M. M. Kasliwal (Caltech), H. Kumar (IITB), A. Sagués Carracedo (OKC, Stockholm University), I. Andreoni (Caltech), V. Bhalerao (IITB) report on behalf of the GROWTH collaboration: Reanalysing the data used in GCN 26476, we provide a revised galaxy list. We cross-matched the LIGO/Virgo localization (GCN 26454) with the HAWC position (GCN 26472) and the GLADE v2.3 catalog (Dalya et al., 2018), to identify sources within the 90% LIGO/Virgo credible volume and within a 3-sigma radius of the HAWC candidate. We find nine matching galaxies, all of which are also in SDSS. The distance parameters from the BAYESTAR localization at the position of the HAWC candidate are DISTMU = 233.78 Mpc, DISTSIGMA = 63.57 Mpc. The mean and standard deviation of distance in this direction are DISTMEAN = 265.97 Mpc, DISTSTD = 59.68 Mpc, and the median distance in this direction is 265.40 Mpc. In the table below, we give the right ascensions and declinations in degrees and luminosity distances in Mpc. The "GW C.L." column provides the LIGO/Virgo 3D credible level within which the galaxy is found (smaller values mean more consistent with the GW position. The "HAWC sigma" column gives the separation from the HAWC position, divided by the HAWC 1-sigma error radius. | RAJ2000 | DEJ2000 | Dist | GW C.L. | HAWC sigma | | ---------- | --------- | ----- |-------- | ---------- | | 323.482422 | +5.279632 | 274.4 | 86 | 0.23 | | 323.056030 | +4.832057 | 219.1 | 72 | 2.06 | | 322.921936 | +5.503483 | 232.2 | 72 | 2.21 | | 322.838806 | +5.255421 | 179.3 | 73 | 2.30 | | 322.821228 | +5.553754 | 338.7 | 81 | 2.59 | | 322.749084 | +5.108610 | 330.8 | 78 | 2.62 | | 323.173767 | +4.467985 | 292.5 | 88 | 2.80 | | 322.906006 | +5.850705 | 323.1 | 85 | 2.93 | | 323.034882 | +4.482058 | 340.7 | 86 | 2.99 | We highlight the first galaxy in this list since it is consistent with both LIGO/Virgo 3D localization and the HAWC 1-sigma angular separation. There is no evidence for significant variability of within this galaxy in either PTF or ZTF. Follow-up of these galaxies is encouraged. Further analysis is ongoing. GROWTH is a worldwide collaboration comprising of 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. ZTF acknowledges the generous support of the NSF under AST MSIP Grant No 1440341. GROWTH acknowledges generous support of the NSF under PIRE Grant No 1545949. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26481 SUBJECT: LIGO/Virgo S191216ap: No transient candidates in CALET observations DATE: 19/12/18 04:06:07 GMT FROM: Yuta Kawakubo at Louisiana State U./CALET T. Sakamoto, A. Yoshida, V. Pal'shin, S. Sugita (AGU), Y. Kawakubo (LSU), K. Yamaoka (Nagoya U), S. Nakahira (RIKEN), Y. Asaoka, S. Torii (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), and the CALET collaboration: The CALET Gamma-ray Burst Monitor (CGBM) was operating at the trigger time of S191216ap T0 = 2019-12-16 21:33:38.473 UT (The LIGO Scientific Collaboration and Virgo Collaboration, GCN Circ. 26454). No CGBM on-board trigger occurred around the event time. Based on the LVC high probability localization region, the summed LIGO probabilities inside the CGBM HXM (7 - 3000 keV) and SGM (40 keV - 28 MeV) fields of view are 0 % and 2 %, respectively (and 26 % credible region of the initial localization map was above the horizon). The HXM and SGM fields of view were centered at RA = 178.2 deg, Dec = 19.5 deg and RA = 186.8 deg, Dec = 13.9 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 low energy trigger mode at the trigger time of S191216ap. Using the CAL data, we have searched for gamma-ray events in the 1-10 GeV band from -60 sec to +60 sec from the GW trigger time and found no candidates. There is no significant overlap with the LVC high probability localization region at T0+-60 sec. The CAL FOV was centered at RA=186.8 deg, Dec=13.9 deg at T0. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26483 SUBJECT: LIGO/Virgo S191216ap: GRAWITA Loiano observations of HAWC error region DATE: 19/12/18 10:44:24 GMT FROM: Andrea Rossi at INAF A. Rossi, M. Dadina, E. Maiorano, R. Gualandi (INAF-OAS), P. D'Avanzo, A. Melandri (INAF-OABr), M.T. Botticella (INAF-OAC), and E. Brocato (INAF-Abruzzo) report on behalf of GRAWITA We observed the inner part of the error box obtained by the HAWC collaboration (Martinez-Castellano GCN #26472) during the follow-up of the GW trigger S191216ap (GCN #26454) with the 152cm Cassini Telescope at Loiano Observatory. The pointing was performed using the R filter. Four 10min exposures have been obtained starting at 18:12:29 on 2019-12-17 (UT), covering a mosaic of ~20'x20'. The observation was affected by bad seeing (4"), low elevation, and passing clouds. In preliminary analysis, assuming R=14.4 for the star at coordinates RA,DEC(J2000) 21:33:59, +05:16:21.5), for the galaxy #1 reported by Singer et al (GCN #26479) we measure R=16.6+-0.1. This is consistent with r=16.5 reported in SDSS catalog, within the photometric system and filter differences. No other obvious candidate is visible down to R=18.5 mag and in comparison to DSS2 survey. ⁣Sent from BlueMail ​ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26486 SUBJECT: LIGO/Virgo S191216ap and IceCube neutrino: no counterpart candidates from AGILE-GRID observations DATE: 19/12/18 16:56:01 GMT FROM: Francesco Verrecchia at SSDC,INAF-OAR F. Verrecchia (SSDC, and INAF/OAR), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), M. Cardillo, A. Ursi, C. Casentini, G. Piano (INAF/IAPS), F. Lucarelli, C. Pittori (SSDC, and INAF/OAR), M. Pilia (INAF/OA-Cagliari), A. Bulgarelli, V. Fioretti, N. Parmiggiani (INAF/OAS-Bologna), F. Longo (Univ. Trieste, and INFN Trieste), report on behalf of the AGILE Team: In response to the LIGO-Virgo GW event S191216ap at T0 = 2019-12-16 21:33:38.473 UTC and the candidate IceCube neutrino (GCN Circ. 26463), an analysis of the AGILE exposure at T0 shows that both the GW localization region (LR) and neutrino error circle (EC) were occulted by the Earth. We performed an analysis of the GRID data over time intervals before and after T0, when good exposures of the S191216ap LR and neutrino EC were available. No candidate gamma-ray transient was detected. The following preliminary GRID values of 3-sigma upper limits (ULs) in the 100 MeV - 10 GeV energy band are obtained over the neutrino position: - 6.9e-11 erg cm^-2 s^-1, with exposure over the time interval (T0 - 3 days; T0); - 4.6e-11 erg cm^-2 s^-1, with exposure over the time interval (T0 - 7 days; T0). As the S191216ap LR became visible, we obtained the following preliminary GRID values of 3-sigma ULs: from 7.7e-08 to 3.9e-07 erg cm^-2 s^-1, with exposure of about 80% of the LR over the time interval (T0 + 1.6ks ; T0 + 1.8ks); 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: 26487 SUBJECT: LIGO/Virgo S191216ap: No candidates found in CHES observations of HAWC error region DATE: 19/12/18 17:47:27 GMT FROM: Tianrui Sun at Purple Mountain Obs,CAS Tianrui Sun, Chen Zhang, Yiding Ping, Xuefeng Wu.(PMO). We observed the corrected list of galaxies coincident with LIGO/Virgo and HAWC positions by Leo Singer (GCN 26479). The observation used the 80cm telescope with the FOV of 2x2 deg^2 of the CHanging Event Survey at the YaoAn observation station(101.1811E, 25.528N) in Yunnan Province, China. Our observations started at 12:04:04UT and ends at 12:55:05UT Dec 18, 2019, with 11 exposure 60 seconds in white filter. Our results for these galaxies: | RA | DEC | Mag(White) | SDSS(r) | | 323.482422 | 5.279632 | 16.42 | 16.50 | | 323.056030 | 4.832057 | 15.94 | 15.83 | | 322.921936 | 5.503483 | 15.70 | 15.57 | | 322.838806 | 5.255421 | 15.60 | 15.41 | | 322.821228 | 5.553754 | 15.64 | 15.83 | | 323.173767 | 4.467985 | 16.09 | 16.10 | | 322.906006 | 5.850705 | 16.69 | 16.84 | | 323.034882 | 4.482058 | 16.27 | 16.24 | And the observations of CHES: Date-obs RA DEC MAG FWHM 2019-12-18T12:04:04 323.1053 5.3952 18.07 3.67 2019-12-18T12:07:48 323.6028 6.0834 17.92 4.18 2019-12-18T12:19:03 323.1023 6.0505 18.08 3.61 2019-12-18T12:20:11 323.1023 6.0507 18.05 3.71 2019-12-18T12:21:26 323.2811 4.3005 17.98 3.83 2019-12-18T12:23:49 323.1022 6.0512 18.02 3.68 2019-12-18T12:24:57 323.1023 6.0515 18.03 3.68 2019-12-18T12:51:43 323.4745 5.3269 17.94 3.87 2019-12-18T12:53:58 323.4746 5.3273 17.91 3.96 2019-12-18T12:55:05 323.4746 5.3273 17.90 3.96 2019-12-18T12:09:03 323.7238 5.8421 17.43 5.50 We did not detect any candidate source related to these galaxies in 5 sigma limit at 18.86 (median combined) generated from G band in Gaia DR2. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26489 SUBJECT: LIGO/Virgo S191216ap: Correction to GCN 26488 (NOWT observations) DATE: 19/12/18 18:40:04 GMT FROM: Dong Xu at NAOC/CAS D. Xu (NAOC) reports: We note that the name of the GW event in the title of GCN 26488 should not be S191213g. It should be S191216ap instead. Sorry for any inconveniences. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26496 SUBJECT: LIGO/Virgo S191216ap: No candidates found in J-GEM follow-up observations of HAWC error region DATE: 19/12/19 07:32:40 GMT FROM: Mahito Sasada at Hiroshima University Yanagisawa, K.; Yoshida, M. (NAOJ); Onozato, H.; Takahashi, J. (U. Hyogo); Itoh, R. (Bisei Astronomical observatory); Takarada, T. (Saitama U.); Sasada, M. (Hiroshima U.); Utsumi, Y. (Stanford/SLAC); Toma, S.; Adachi, R.; Murata, K. L. (Tokyo Tech.) on behalf of J-GEM collaboration Following detections of the LIGO-Virgo (S191216ap; Piotrzkowski, GCN Circ. 26454), IceCube (Hussain, CGN Circ. 26460) and HAWC (Martinez-Castellano, GCN Circ. 26472), we performed imaging observations of a galaxy, GL213356+051647, selected from our candidate selection algorithm based on the GLADE v2.3 catalog (Dalya et al., 2018) and those localizations. Our candidate galaxy is also ranked as the top candidate in Singer, GCN Circ. 26479. We started our observations from 2019-12-18 08:11 UT (MJD=58835.34) and ended at 2019-12-18 10:27 UT (MJD=58835.44). We found no apparent transient objects in these galaxies to 5 sigma limiting magnitudes in the AB system listed below. galid ra dec dist J H Ks Ic g$B!G(B Rc obsid --------------- -------- ------ ------ ---- ---- ---- ---- ---- ---- ---------------------------------------- GL213356+051647 323.4824 5.2796 274.42 17.8 18.3 18.1 18.5 16.5 17.0 OAOWFC,Nayuta-NIC,BAO101cm,MITSuME-Akeno BAO101cm: 101 cm telescope at Bisei Astronomical Observatory and CCD optical camera (Ic) MITSuME-Akeno: 50 cm MITSuME telescope at Akeno Observatory and a 3 color imager (g$B!G(B, Rc, Ic) Nayuta-NIC: 200 cm Nayuta telescope at Nishi-Harima Astronomical Observatory and Nishiharima Infrared Camera, NIC (J, H, Ks) OAOWFC: 91 cm Okayama Astrophysical Observatory NIR Wide Field Camera, OAOWFC (J) (Yanagisawa et al., 2019, PASJ, 71, 118) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26498 SUBJECT: LIGO/Virgo S191216ap, Swift XRT observations: 16 X-ray sources in the HAWC error region search DATE: 19/12/19 09:22:13 GMT FROM: Phil Evans at U of Leicester P.A. Evans (U. Leicester), J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto), S.D. Barthelmy (NASA/GSFC), A.P. Beardmore (U. Leicester), M.G. Bernardini (INAF-OAB), A.A. Breeveld (UCL-MSSL), P. Brown (TAMU), 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.W.K. Emery (UCL-MSSL), P. Giommi (ASI), C. Gronwall (PSU), D. Hartmann (U. Clemson), H.A. Krimm (CRESST/GSFC/USRA), N.J. Klingler (PSU), N.P.M. Kuin (UCL-MSSL), A.Y. Lien (GSFC/UMBC), F.E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB), J.A. Nousek (PSU), S.R. Oates (U. Birmingham), P.T. O'Brien (U. Leicester), J.P. Osborne (U. Leicester), C. Pagani (U. Leicester), K.L. Page (U.Leicester), M.J.Page (UCL-MSSL), D.M. Palmer (LANL), M. Perri (ASDC), J.L. Racusin (NASA/GSFC), B. Sbarufatti (INAF-OAB/PSU), M.H. Siegel (PSU), G. Tagliaferri (INAF-OAB), E. Troja (NASA/GSFC/UMCP) report on behalf of the Swift team: Swift has carried out further observations of S191216ap. We performed a series of tiles to cover the HAWC error region (GCN Circ. 26472) for 500 s per tile, and then 3ks observations of each of the galaxies listed by Singer et al (GCN Circ. 26479). All of the Swift pointings and associated metadata have been reported to the Treasure Map (Wyatt et al., GCN Circ. 26244; http://treasuremap.space/alerts?graceids=S191216ap). In these observations, we detected 17 X-ray sources, these are either new detections, or have been given a higher 'rank' than in the last circular. Each source is assigned a rank of 1-4 which describes how likely it is to be related to the GW trigger, with 1 being the most likely and 4 being the least likely. The ranks are described at https://www.swift.ac.uk/ranks.php. We have found: * 0 sources of rank 1 * 0 sources of rank 2 * 13 sources of rank 3 * 4 sources of rank 4 RANK 3 sources ============== These are uncatalogued X-ray sources, however they are not brighter than previous upper limits, so do not stand out as likely counterparts to the GW trigger. | Source ID | RA | Dec | Err90 | | S191216ap_X4 | 21h 33m 49.19s | +04d 57' 18.9" | 6.7" | | S191216ap_X5 | 21h 33m 18.81s | +05d 17' 04.9" | 6.9" | | S191216ap_X6 | 21h 34m 53.19s | +05d 19' 11.0" | 6.6" | | S191216ap_X7 | 21h 32m 44.20s | +04d 20' 06.0" | 5.8" | | S191216ap_X8 | 21h 32m 47.89s | +04d 27' 52.2" | 5.5" | | S191216ap_X9 | 21h 32m 26.75s | +04d 21' 31.6" | 5.3" | | S191216ap_X10 | 21h 32m 6.50s | +04d 18' 38.2" | 6.9" | | S191216ap_X12 | 21h 31m 46.59s | +05d 44' 44.4" | 7.0" | | S191216ap_X13 | 21h 31m 56.80s | +05d 11' 22.4" | 8.0" | | S191216ap_X17 | 21h 31m 43.77s | +05d 25' 15.7" | 6.0" | | S191216ap_X19 | 21h 31m 57.63s | +04d 43' 38.4" | 7.4" | | S191216ap_X20 | 21h 31m 31.98s | +04d 54' 03.0" | 5.0" | | S191216ap_X21 | 21h 31m 44.49s | +05d 23' 12.0" | 7.4" | RANK 4 sources ============== These are catalogued X-ray sources, showing no signs of outburst compared to previous observations, so they are not likely to be related to the GW trigger. | Source ID | RA | Dec | Err90 | | S191216ap_X11 | 21h 32m 41.01s | +04d 24' 18.6" | 6.2" | | S191216ap_X14 | 21h 30m 32.91s | +05d 02' 18.4" | 7.6" | | S191216ap_X15 | 21h 30m 26.31s | +05d 06' 07.0" | 7.2" | | S191216ap_X16 | 21h 31m 22.64s | +05d 02' 37.5" | 5.4" | For all flux conversions and comparisons with catalogues and upper limits from other missions, we assumed a power-law spectrum with NH=3x10^20 cm^-2, and photon index (Gamma)=1.7 The results of the XRT automated analysis, including details of the sources listed above, are online at https://www.swift.ac.uk/LVC/S191216ap This circular is an official product of the Swift XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26505 SUBJECT: LIGO/Virgo S191216ap: Updated Sky Localization DATE: 19/12/19 17:59:21 GMT FROM: Brandon Piotrzkowski at U of Wisconsin-Milwaukee The LIGO Scientific Collaboration and the Virgo Collaboration report: We have conducted further analysis of the LIGO Hanford Observatory (H1) and Virgo Observatory (V1) data around the time of the compact binary merger (CBC) candidate S191216ap (GCN Circular 26454). Parameter estimation has been performed using LALInference [1] and a new sky map, LALInference.fits.gz,0, distributed via GCN Notice, is available for retrieval from the GraceDB event page: https://gracedb.ligo.org/superevents/S191216ap The preferred sky map at this time is LALInference.fits.gz,0. For the LALInference.fits.gz,0 sky map, the 90% credible region is 253 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 376 +/- 70 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] Veitch et al. PRD 91, 042003 (2015) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26507 SUBJECT: LIGO/Virgo S191216ap: UPDATED list of galaxies coincident with LIGO/Virgo LALInference skymap and HAWC positions DATE: 19/12/20 04:18:37 GMT FROM: Shreya Anand at GROWTH Caltech T. Ahumada (UMD), S. Anand (Caltech), and L.P. Singer (NASA-GSFC)report on behalf of the GROWTH collaboration: Based on the new LALInference map (GCN 26505), we re-ran our galaxy cross-match from GCN 26479 with the HAWC position (GCN 26472)and the GLADE v2.3 catalog (Dalya et al., 2018), to identify sources within the 90% LIGO/Virgo credible volume and within a 3-sigma radius of the HAWC candidate. Our updated search yields only three matching galaxies, which were in our previously reported list of galaxies (GCN 26479). All of the galaxies in our previous list are within the 95% 3D credible level in the LALInference map; we report only those galaxies still within the 90% 3D credible level. The distance parameters from the LALInference localization at the position of the HAWC candidate are DISTMU= 272.35 Mpc and DISTSIGMA= 44.52 Mpc. In the table below, we give the right ascensions and declinations in degrees and luminosity distances in Mpc. The "GW C.L." column provides the LIGO/Virgo 3D credible level within which the galaxy is found (smaller values mean more consistent with the GW position). The "HAWC sigma" column gives the separation from the HAWC position, divided by the HAWC 1-sigma error radius. | RAJ2000 | DEJ2000 | Dist | GW C.L. | HAWC sigma | | ---------- | --------- | ----- |-------- | ---------- | | 322.821228 | +5.553754 | 338.7 | 81 | 2.59 | | 322.749084 | +5.108610 | 330.8 | 78 | 2.62 | | 323.034882 | +4.482058 | 340.7 | 86 | 2.99 | GROWTH is a worldwide collaboration comprising of 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. ZTF acknowledges the generous support of the NSF under AST MSIP Grant No 1440341. GROWTH acknowledges generous support of the NSF under PIRE Grant No 1545949. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26509 SUBJECT: LIGO/Virgo S191216ap: Subaru/Hyper Suprime-Cam observations of GW+IceCube+HAWC error region DATE: 19/12/20 07:26:15 GMT FROM: Takayuki Ohgami at Konan University T. Ohgami, N. Tominaga (Konan U.), R. Ohsawa, Y. Niino, T. Morokuma (U. Tokyo), T. Terai, Y. Takagi, K. Yanagisawa, M. Yoshida (NAOJ), M. Sasada (Hiroshima U.), M. Tanaka (Tohoku U.), Y. Sekiguchi (Toho U.), Y. Utsumi (Stanford/SLAC) on behalf of J-GEM collaboration Following detections of S191216ap by LIGO-Virgo (Piotrzkowski et al., GCN Circ. 26454, 26505) and possible related events by IceCube (Hussain et al., CGN Circ. 26460) and by HAWC (Martinez-Castellano et al., GCN Circ. 26472), we selected a galaxy, GL213356+051647 (ra, dec = 323.4824, 5.2796 at 274.42 Mpc), from our candidate selection algorithm based on the GLADE v2.3 catalog (Dalya et al., 2018) and the localization maps. Our candidate galaxy is also ranked as the top candidate in Singer et al. (GCN Circ. 26479). Using a 1.5 deg circular aperture of Subaru/Hyper Suprime-Cam which covers the HAWC's 68% credible region, we imaged a region around GL213356+051647 with an integration time of 2730 sec for z-band, starting from 2019-12-20 05:06 UT. An estimated limiting magnitude is 25.5. We found no apparent transient associated with GL213356+051647. More detailed analysis is ongoing, and further follow-up observations are planned. We thank Subaru's staff for making this observation. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26511 SUBJECT: LIGO/Virgo S191216ap: AstroSat CZTI upper limits DATE: 19/12/20 09:15:02 GMT FROM: Varun Bhalerao at Indian Inst of Tech V. Shenoy (IITB), Aarthy E. (PRL), V. Bhalerao (IITB), D. Bhattacharya (IUCAA), A. R. Rao (TIFR), S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration: We have carried a search for X-ray candidates in Astrosat CZTI data in a 100 sec window around the trigger time of the MassGap merger event S191216ap (UTC 2019-12-16 21:33:38, 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,DEC = 08:19:21.4,70:39:40.4 (124.8392,70.6612), which is ~79 deg away from the maximum probability location, which severely reduces the effective area of CZTI. At the time of merger event, the Earth-satellite-transient angle corresponding to maximum probability location is ~ 151 deg and hence is not occulted by Earth in satellite's frame. In a time interval of 100 sec around the event, the region of the LALInference map (LVC GCN 26505) which is not occulted by Earth in the satellite's frame has a cumulative probability of 1.0 (100%). CZTI data were de-trended to remove orbit-wise background variation. We then searched data from 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 background 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 use a detailed mass model of the satellite to calculate the direction-dependent instrument response for points in the visible sky. We then assume the source is modelled as a power law with photon index alpha = -1, and convert our count rate upper limits to direction-dependent flux limits. We obtain the following upper limits for source flux in the 20-200 keV band by taking a probability weighted mean over the visible sky: 0.1 s: flux limit= 3.69e-05 ergs/cm^2/s; fluence limit = 3.69e-06 ergs/cm^2 1.0 s: flux limit= 1.09e-05 ergs/cm^2/s; fluence limit = 1.09e-05 ergs/cm^2 10.0 s: flux limit= 1.61e-06 ergs/cm^2/s; fluence limit = 1.61e-05 ergs/cm^2 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: 26528 SUBJECT: LIGO/Virgo S191216ap : No significant candidates in FRAM-TAROT-GRANDMA observations DATE: 19/12/21 09:25:19 GMT FROM: Martin Blazek at HETH/IAA-CSIC P.A. Duverne (LAL), S. Agayeva (SHAO), M. Blazek (HETH/IAA-CSIC), M. Masek (FZU), S. Karpov, M. Prouza (FZU), M. Boer (Artemis), N. Christensen (Artemis), L. Eymar (Artemis), A. Klotz (IRAP), K. Noysena (Artemis,IRAP), S. Antier (APC), A. Coleiro (APC), D. Corre (LAL), M. Coughlin (Caltech), D. Coward (OzGrav-UWA), J.G. Ducoin (LAL), B. Gendre (OzGrav-UWA), P. Hello (LAL), D. A. Kann (HETH/IAA-CSIC), N. Kochiashvili (Iliauni), C. Lachaud (APC), N. Leroy (LAL), C. Thoene (HETH/IAA-CSIC), D. Turpin (AIM-CEA), X. Wang (THU) report on behalf of the FRAM, TAROT and GRANDMA collaborations. We performed tiled observations of LIGO/Virgo S191216ap event (#GCN 26454) with the FRAM-Auger, FRAM-CTA-N, TAROT-Calern (TCA), TAROT-Chili (TCH) telescopes. FRAM-Auger is located at Pierre Auger Observatory. FRAM-CTA-N is located at Observatorio del Roque de los Muchachos. TCA is located at Calern site at the Cote d'Azur observatory. TCH is located at La Silla ESO observatory (LaS/ESO). +-------------+---------+----------+-------------+------------+ | Telescope | Delay | Filter | f.o.v. | Limiting | | | [min] | | [deg] | Mag. | |-------------+---------+----------+-------------+------------| | FRAM-Auger | 228 | R | 1.0 x 1.0 | 18.0 (60s) | | FRAM-CTA-N | 1296 | R | 0.45 x 0.45 | 17.0 (90s) | | TCA | 1166 | Clear | 1.9 x 1.9 | 18.0 (60s) | | TCH | 1658 | Clear | 1.9 x 1.9 | 18.0 (60s) | +-------------+---------+----------+-------------+------------+ We performed the following joint tiled observations [1] : +-------------+------------+------------+---------+---------+---------+ | Telescope | TStart | TEnd | RA | DEC | Proba | | | [UTC] | [UTC] | [deg] | [deg] | [%] | |-------------+------------+------------+---------+---------+---------| | FRAM-Auger | 2019-12-17 | 2019-12-17 | 321.186 | -1.460 | 0.3 | | | 01:20:58 | 01:22:58 | | | | | FRAM-Auger | 2019-12-17 | 2019-12-17 | 321.081 | -2.432 | 0.2 | | | 01:25:12 | 01:29:39 | | | | | FRAM-Auger | 2019-12-17 | 2019-12-17 | 321.081 | -3.405 | 0.2 | | | 01:31:14 | 01:33:14 | | | | | FRAM-Auger | 2019-12-17 | 2019-12-17 | 320.976 | -5.351 | 0.2 | | | 01:48:45 | 01:53:12 | | | | | FRAM-Auger | 2019-12-17 | 2019-12-17 | 320.763 | -8.270 | 0.3 | | | 01:54:07 | 01:58:34 | | | | | FRAM-Auger | 2019-12-17 | 2019-12-17 | 320.870 | -6.324 | 0.2 | | | 01:59:16 | 02:03:43 | | | | | FRAM-Auger | 2019-12-17 | 2019-12-17 | 321.744 | -8.270 | 0.2 | | | 02:04:34 | 02:09:01 | | | | | FRAM-Auger | 2019-12-17 | 2019-12-17 | 321.534 | -10.216 | 0.2 | | | 02:19:59 | 02:24:26 | | | | | ----- | ----- | ----- | ----- | ----- | ----- | | FRAM-CTA-N | 2019-12-17 | 2019-12-17 | 318.536 | 27.312 | 0.2 | | | 19:09:06 | 19:13:12 | | | | | FRAM-CTA-N | 2019-12-17 | 2019-12-17 | 318.365 | 27.749 | 0.2 | | | 19:13:31 | 19:17:37 | | | | | FRAM-CTA-N | 2019-12-17 | 2019-12-17 | 318.668 | 25.565 | 0.2 | | | 19:17:52 | 19:21:58 | | | | | FRAM-CTA-N | 2019-12-17 | 2019-12-17 | 318.045 | 27.312 | 0.2 | | | 19:22:14 | 19:26:20 | | | | | FRAM-CTA-N | 2019-12-17 | 2019-12-17 | 319.110 | 24.254 | 0.2 | | | 19:26:36 | 19:30:42 | | | | | FRAM-CTA-N | 2019-12-17 | 2019-12-17 | 319.184 | 25.565 | 0.2 | | | 19:31:02 | 19:35:08 | | | | | FRAM-CTA-N | 2019-12-17 | 2019-12-17 | 317.209 | 31.681 | 0.2 | | | 19:35:24 | 19:39:30 | | | | | FRAM-CTA-N | 2019-12-17 | 2019-12-17 | 317.126 | 30.808 | 0.2 | | | 19:39:45 | 19:43:51 | | | | | FRAM-CTA-N | 2019-12-17 | 2019-12-17 | 317.025 | 32.118 | 0.2 | | | 19:44:05 | 19:48:11 | | | | | FRAM-CTA-N | 2019-12-17 | 2019-12-17 | 317.392 | 31.244 | 0.2 | | | 19:48:30 | 19:52:36 | | | | | FRAM-CTA-N | 2019-12-17 | 2019-12-17 | 316.777 | 32.555 | 0.2 | | | 19:52:51 | 19:56:57 | | | | | FRAM-CTA-N | 2019-12-17 | 2019-12-17 | 318.192 | 28.186 | 0.2 | | | 19:57:14 | 20:01:20 | | | | | FRAM-CTA-N | 2019-12-17 | 2019-12-17 | 318.018 | 28.623 | 0.2 | | | 20:01:34 | 20:05:40 | | | | | FRAM-CTA-N | 2019-12-17 | 2019-12-17 | 319.864 | 19.885 | 0.2 | | | 20:06:02 | 20:10:08 | | | | | FRAM-CTA-N | 2019-12-17 | 2019-12-17 | 316.589 | 32.992 | 0.2 | | | 20:10:30 | 20:14:36 | | | | | FRAM-CTA-N | 2019-12-17 | 2019-12-17 | 317.843 | 29.060 | 0.2 | | | 20:14:54 | 20:19:00 | | | | | FRAM-CTA-N | 2019-12-17 | 2019-12-17 | 317.717 | 29.497 | 0.2 | | | 20:19:13 | 20:23:19 | | | | | FRAM-CTA-N | 2019-12-17 | 2019-12-17 | 319.616 | 24.254 | 0.1 | | | 20:23:36 | 20:27:42 | | | | | FRAM-CTA-N | 2019-12-17 | 2019-12-17 | 317.308 | 30.371 | 0.2 | | | 20:27:58 | 20:32:04 | | | | | FRAM-CTA-N | 2019-12-17 | 2019-12-17 | 317.488 | 29.934 | 0.2 | | | 20:32:24 | 20:36:30 | | | | | ----- | ----- | ----- | ----- | ----- | ----- | | TCA | 2019-12-17 | 2019-12-18 | 316.229 | 35.280 | 2.9 | | | 16:59:02 | 20:11:43 | | | | | TCA | 2019-12-17 | 2019-12-20 | 317.995 | 26.002 | 2.5 | | | 18:07:04 | 18:43:14 | | | | | TCA | 2019-12-17 | 2019-12-20 | 313.891 | 38.991 | 3.1 | | | 18:13:50 | 18:49:58 | | | | | TCA | 2019-12-18 | 2019-12-18 | 315.090 | 37.136 | 3.2 | | | 19:13:09 | 19:19:31 | | | | | TCA | 2019-12-20 | 2019-12-20 | 317.502 | 27.857 | 2.7 | | | 18:17:44 | 18:24:03 | | | | | TCA | 2019-12-20 | 2019-12-20 | 318.715 | 24.146 | 2.4 | | | 18:24:28 | 18:30:47 | | | | | TCA | 2019-12-20 | 2019-12-20 | 317.048 | 33.424 | 2.6 | | | 18:51:09 | 18:57:29 | | | | | TCA | 2019-12-20 | 2019-12-20 | 315.950 | 31.569 | 2.4 | | | 19:02:54 | 19:09:13 | | | | | TCA | 2019-12-20 | 2019-12-20 | 312.628 | 40.847 | 2.7 | | | 19:09:35 | 19:11:35 | | | | | TCA | 2019-12-20 | 2019-12-20 | 319.571 | 27.857 | 1.3 | | | 19:33:09 | 19:35:09 | | | | | TCA | 2019-12-20 | 2019-12-20 | 314.852 | 33.424 | 1.9 | | | 19:39:53 | 19:41:53 | | | | | TCA | 2019-12-20 | 2019-12-20 | 313.993 | 35.280 | 1.6 | | | 19:48:00 | 19:54:19 | | | | | TCA | 2019-12-20 | 2019-12-20 | 309.886 | 44.558 | 2.1 | | | 19:54:45 | 20:01:04 | | | | | TCA | 2019-12-20 | 2019-12-20 | 320.726 | 23.671 | 0.7 | | | 20:01:29 | 20:07:49 | | | | | ----- | ----- | ----- | ----- | ----- | ----- | | TCH | 2019-12-18 | 2019-12-18 | 319.592 | -9.050 | 0.2 | | | 01:11:08 | 01:17:27 | | | | | TCH | 2019-12-18 | 2019-12-18 | 319.385 | -10.868 | 0.2 | | | 01:17:52 | 01:24:10 | | | | | TCH | 2019-12-21 | 2019-12-21 | 319.797 | -7.232 | 0.3 | | | 01:34:12 | 01:38:21 | | | | +-------------+------------+------------+---------+---------+---------+ TStart and TEnd refers respectively to the time of the first and last exposure for a given tile. Observations are not necessarily continuous in this interval. The Probability refers to the 2D spatial probability of the GW skymap enclosed in a given tile. These observations cover about 35.4% of the cumulative probability of the LALInference skymap created on 2019-12-19 17:30:31 (UTC). The coverage map is available at: https://grandma-owncloud.lal.in2p3.fr/index.php/s/XgtMhPRxcyL09gR/ download?path=%2F&files=GRANDMA_S191216ap_1576913351.png No significant transient candidates were found during our low latency analysis [2,3]. GRANDMA (Global Rapid Advanced Network Devoted to the Multi-messenger Addicts) is a network of robotic telescopes connected all over the world with both photometry and spectrometry capabilities for Time- domain Astronomy [2](https://grandma.lal.in2p3.fr/). Details on the different telescopes are available on the GRANDMA web pages. [1] M. W Coughlin et al., MNRAS 2019, https://doi.org/10.1093/mnras/stz2485 [2] S. Antier et al., MNRAS 2019, https://doi.org/10.1093/mnras/stz3142 [3] K. Noysena et al., ApJ 2019, arXiv:1910.02770 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26529 SUBJECT: LIGO/Virgo S191216ap: MASTER optical observation DATE: 19/12/21 16:50:55 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa,A.Kuznetsov,F.Balakin, K.Zhirkov, V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva, A.Chasovnikov, D.Kuvshinov (Lomonosov Moscow State University, SAI, Physics Department), O.A. Gres, N.M. Budnev, O.Ershova (Irkutsk State University, API), R. Podesta, C.Lopez, F. Podesta, C.Francile(Observatorio Astronomico FelixAguilar 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), V. Yurkov, A. Gabovich, Yu. Sergienko(Blagoveschensk Educational State University) A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), MASTER covered 812 square degrees of S191216ap ( MassGap (>99%); 324+/-78Mpc LVC GCN 26454, Lipunov et al. GCN 26457, GCN 26474; Barthelmy collection https://gcn.gsfc.nasa.gov/other/S191216ap.gcn3) that is equal to 92% of full error-box https://master.sai.msu.ru/site/master2/ligo_1.php?id=11073 We report MASTER observation of the galaxies cross-matched with LVC and HAWC localization (Singer et al. GCN 26479) without OT detection with the following limits: Galaxy_Coordinates MASTER_first_image_UT mlim (unfiltered) MASTER_observatory 323.482422 +5.279632 2019-12-17 09:53:01 17.0 MASTER-Amur 2019-12-17 10:54:13 18.6 MASTER-Tunka 2019-12-17 15:53:25 18.6 MASTER-Kislovodsk 323.056030 +4.832057 2019-12-17 09:41:42 17.3 MASTER-Amur 2019-12-17 12:09:47 18.6 MASTER-Tunka 2019-12-20 15:39:40 18.6 MASTER-Tavrida 322.921936 +5.503483 2019-12-17 09:53:01 17.0 MASTER-Amur 2019-12-17 10:54:13 18.3 MASTER-Tunka 2019-12-20 15:39:40 18.6 MASTER-Tavrida 2019-12-18 16:40:44 18.5 MASTER-Kislovodsk 322.838806 +5.255421 2019-12-17 09:53:01 17.0 MASTER-Amur 2019-12-17 12:09:47 18.6 MASTER-Tunka 2019-12-17 15:53:25 18.6 MASTER-Kislovodsk 2019-12-20 15:39:40 18.6 MASTER-Kislovodsk 322.821228 +5.553754 2019-12-17 09:53:01 17.0 MASTER-Amur 2019-12-17 10:54:13 18.3 MASTER-Tunka 2019-12-20 15:39:40 18.6 MASTER-Tavrida 322.749084 +5.108610 2019-12-17 09:53:01 17.0 MASTER-Amur 2019-12-17 12:09:47 18.6 MASTER-Tunka 2019-12-17 15:32:09 19.6 MASTER-Tavrida 2019-12-18 15:54:04 20.0 MASTER-Tavrida 323.173767 +4.467985 2019-12-17 09:41:42 17.3 MASTER-Amur 2019-12-17 15:53:25 18.6 MASTER-Kislovodsk 2019-12-20 15:39:40 18.6 MASTER-Tavrida 322.906006 +5.850705 2019-12-17 09:53:01 17.0 MASTER-Amur 2019-12-17 10:54:13 18.3 MASTER-Tunka 2019-12-17 16:30:37 18.5 MASTER-Kislovodsk 2019-12-20 15:39:40 18.6 MASTER-Tavrida 323.034882 +4.482058 2019-12-17 09:41:42 17.3 MASTER-Amur 2019-12-17 15:53:25 18.6 MASTER-Tunka 2019-12-20 15:39:40 18.6 MASTER-Tavrida The analysys will be continued. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26530 SUBJECT: LIGO/Virgo S191216ap: No radio candidates so far in the VLA/JAGWAR galaxy targeted search DATE: 19/12/21 18:33:11 GMT FROM: Kunal Mooley at NRAO,Caltech Kunal Mooley (NRAO, Caltech; Jansky Fellow), Steve Myers, Dale Frail (NRAO), Gregg Hallinan, Shri Kulkarni, Mansi Kasliwal (Caltech), Alessandra Corsi (TTU), Leo Singer (GSFC) report on behalf of the JAGWAR team We observed the 9 GLADE galaxies (Singer et al. GCN 26479) consistent with the HAWC/gamma-ray (Martinez-Castellanos et al. GCN 26472) and S191216ap/BAYESTAR localization volume (Piotrzkowski et al. GCN 26454) with the VLA between 4-8 GHz on 2019 Dec 18-19. No point-like sources are detected within 50 kpc of any of the galaxies down to 20 uJy (3sigma), except many of the galaxies have radio sources coincident with their nuclei (see table below). Follow up VLA observations are planned. | RAJ2000    | DEJ2000   | Dist  | Flux_6GHz| Comments | deg        | deg       | Mpc   | uJy      | | ---------- | --------- | ----- | -------- | -------------------- | 323.482422 | +5.279632 | 274.4 | 820      | unresolved (12" beam) | 323.056030 | +4.832057 | 219.1 | 370      | marginally resolved | 322.921936 | +5.503483 | 232.2 | 80       | resolved | 322.838806 | +5.255421 | 179.3 | 140      | unresolved | 322.821228 | +5.553754 | 338.7 | 180      | unresolved ** | 322.749084 | +5.108610 | 330.8 | 155      | unresolved ** | 323.173767 | +4.467985 | 292.5 | <20      | | 322.906006 | +5.850705 | 323.1 | <15      | | 323.034882 | +4.482058 | 340.7 | <20      | ** (**) We note that only these 3 galaxies (Ahumada et al. GCN 26507) lie within the 95% 3D credible volume in the latest LALInference map (Piotrzkowski et al. GCN 26505) for S191216ap. We thank the NRAO staff for scheduling and executing these observations. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26531 SUBJECT: LIGO/Virgo S191216ap: VLA/JAGWAR radio monitoring of the 1-sigma HAWC region DATE: 19/12/21 18:40:24 GMT FROM: Kunal Mooley at NRAO,Caltech Kunal Mooley (NRAO, Caltech; Jansky Fellow), Steve Myers, Dale Frail (NRAO), Alessandra Corsi, Arvind Balasubramanian, Deven Bhakta (TTU), Gregg Hallinan, Shri Kulkarni (Caltech), report on behalf of the JAGWAR team We have initiated deep C band (4-8 GHz) multi-epoch observations of the 1-sigma containment region (0.3 sq deg; HAWC Collaboration, GCN 25333) coincident with the GW event S191216ap with the Karl G. Jansky Very Large Array. A total of 37 pointings (7 arcmin FWHM primary beam at 6 GHz; pointing coordinates given below), observed as part of the JAGWAR program, will achieve a uniform RMS noise of ~8 uJy over the survey region. We will report any radio transients found through the GCN system. Ra, Dec of the VLA C band pointings: 21:33:11.42  +05:08:26.36 21:33:00.22  +05:14:02.38 21:33:11.42  +05:19:38.36 21:33:33.82  +04:57:14.34 21:33:22.62  +05:02:50.35 21:33:33.82  +05:08:26.34 21:33:22.62  +05:14:02.35 21:33:33.82  +05:19:38.34 21:33:22.62  +05:25:14.35 21:33:33.83  +05:30:50.34 21:33:56.22  +04:57:14.31 21:33:45.02  +05:02:50.33 21:33:56.22  +05:08:26.31 21:33:45.02  +05:14:02.32 21:33:56.22  +05:19:38.31 21:33:45.02  +05:25:14.32 21:33:56.23  +05:30:50.31 21:34:18.62  +04:57:14.29 21:34:07.42  +05:02:50.30 21:34:18.62  +05:08:26.29 21:34:07.42  +05:14:02.30 21:34:18.62  +05:19:38.29 21:34:07.43  +05:25:14.30 21:34:18.63  +05:30:50.29 21:34:41.02  +04:57:14.26 21:34:29.82  +05:02:50.27 21:34:41.02  +05:08:26.26 21:34:29.82  +05:14:02.27 21:34:41.03  +05:19:38.26 21:34:29.83  +05:25:14.27 21:34:41.03  +05:30:50.26 21:34:52.22  +05:02:50.25 21:35:03.42  +05:08:26.23 21:34:52.22  +05:14:02.25 21:35:03.43  +05:19:38.23 21:34:52.23  +05:25:14.25 21:35:14.63  +05:14:02.22 We thank the NRAO staff for scheduling and executing these observations. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26563 SUBJECT: LIGO/Virgo S191216ap: No significant candidates found in Pan-STARRS observations DATE: 19/12/22 21:46:21 GMT FROM: O. McBrien at QUB O. McBrien, S. J. Smartt, K. W. Smith, D. R. Young, J. Gillanders. S. Srivastav, P. Clark, D. O'Neill, M. Fulton (QUB), K.C. Chambers , M. E. Huber, A.S.B. Schultz, T. de Boer, J. Bulger, J. Fairlamb, C.C. Lin, T. Lowe, E. Magnier , R. J. Wainscoat, M. Willman (IfA, Univ. Hawaii), A. Rest (STScI), C. Stubbs (Harvard), T.-W. Chen (Stockholm) on behalf of the Pan-STARRS collaboration report: We have surveyed the sky localisation region of the gravitational wave event S191216ap (The LIGO Scientific Collaboration and the Virgo Collaboration, GCN 26454) with Pan-STARRS1 (Chambers et al. 2016, arXiv:1612.05560), according to the most recently available skymap (LALInference.fits.gz, GCN 26505), and find 15 transient objects within the 90% probability contour. Our survey covers 58.8% of this contour’s area. Our coverage began on MJD 58834.210 (UTC 2019-12-17 05:01:45), though poor weather limited observing time severely on this night. Observations continued over the following 3 subsequent nights, all comprised of 45 second tiling exposures in the PS1-r band. Of the 15 objects found, 8 are known objects already registered on the Transient Name Server. For the remaining 7 objects, 6 appear to be supernova-like events, with relatively flat lightcurves and a host visible in the exposures, while 1 is an M-dwarf flare. We discuss these 7 new objects below: PS19him (AT2019xfh) was discovered at coordinates RA=21:22:43.25, Dec=+08:47:04.9 and magnitude 19.10 +/- 0.09 on MJD 58836.233 in the PS1-r band. PS19him is associated with the galaxy SDSS J212243.21+084705.7 at a photometric redshift of 0.117 +/- 0.034. The object was detected on the subsequent night at a similar magnitude. The flatness of the lightcurve suggests this is a supernova. PS19hir (AT2019xfj) was discovered at coordinates RA=21:24:08.71, Dec=+13:46:38.8 and magnitude 19.80 +/- 0.15 on MJD 58836.235 in the PS1-r band. PS19hir is associated with the galaxy 2MASS J21240870+1346392 with a photometric redshift of 0.170 ± 0.0245. The object was detected on the subsequent night at a similar magnitude. The flatness of the lightcurve suggests this is a supernova. PS19hik (AT2019xej) was discovered at coordinates RA=21:28:18.25, Dec=+03:48:56.8 and magnitude 19.12 +/- 0.11 on MJD 58836.232 in the PS1-r band. PS19hik is associated with the galaxy 2MASS J21281825+0348568 at a photometric redshift of 0.2260 ± 0.0627. The object was detected on the subsequent night at a similar magnitude. The flatness of the lightcurve suggests this is a supernova. PS19hix (AT2019xfr) was discovered at coordinates RA=21:14:34.24, Dec=+29:03:22.0 and magnitude 20.54 +/- 0.27 on MJD 58836.229 in the PS1-r band. PS19hix does not appear to be associated with any catalogued galaxy, but lies near a faint, extended source in the PS1 exposure which is likely a galaxy. Additionally, the object was detected on the subsequent night at a similar magnitude, leading us to believe this is a supernova. PS19his (AT2019xfk) was discovered at coordinates RA=21:17:50.87, Dec=+29:32:55.1 and magnitude 20.78 +/- 0.29 on MJD 58836.229 in the PS1-r band. PS19his does not appear to be associated with any catalogued galaxy, but lies near a faint, extended source in the PS1 exposure which is likely a galaxy. Additionally, the object was detected on the subsequent night at a similar magnitude, leading us to believe this is a supernova. PS19hiy (AT2019xgz) was discovered at coordinates RA=21:18:49.41, Dec=+12:38:49.5 and magnitude 20.15 +/- 0.25 on MJD 58836.260 in the PS1-r band. PS19hiy is associated with the galaxy SDSS J211849.20+123849.5 at a photometric redshift of 0.284 ± 0.106. The object was detected on the subsequent night at a similar magnitude. The flatness of the lightcurve suggests this is a supernova. PS19hiv (AT2019xfn) was discovered at coordinates RA=21:14:01.57, Dec=+22:36:54.9 and magnitude 18.41 +/- 0.05 on MJD 58837.270 in the PS1-r band. PS19hiv is a fast fading, faint, red source. As such, we believe this to be an M-dwarf flare. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26569 SUBJECT: LIGO/Virgo S191216ap: Upper limits from Insight-HXMT/HE observations DATE: 19/12/23 14:58:42 GMT FROM: Qi Luo at IHEP Q. Luo, Y. G. Zheng, C. Cai, S. Xiao, Q. B. Yi, Y. Huang, C. K. Li, G. Li, X. B. 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 S191216ap GW event (GCN #26454). At the GW trigger time 2019-12-16T21:33:38.473 UTC (denoted as T0), 0.96% of the GW localization region was covered by the 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 GW location probability map (RA=288.6 deg, DEC=61.1 deg) without occultation by the Earth, 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: 5.8e-08 erg cm^-2 10 s: 1.9e-07 erg cm^-2 Band model 2 (alpha=-1.0, beta=-2.3, Ep=230 keV): 1 s: 1.0e-07 erg cm^-2 10 s: 3.4e-07 erg cm^-2 Band model 3 (alpha=-0.0, beta=-1.5, Ep=1000 keV): 1 s: 2.7e-07 erg cm^-2 10 s: 1.1e-06 erg cm^-2 Futhermore, from T0-15 minutes to T0+21 minutes, both the IceCube counterpart neutrino candidate (GCN #26450) and the HAWC sub-threshold event (GCN #26472) were invisible to Insight-HXMT due to the Earth shielding. Assuming that the counterpart GRB comes from the HAWC location (RA=323.5 deg, DEC=5.2 deg), we estimated 5-sigma upper-limits (0.2 - 5 MeV, incident energy) of the extended emission of this GRB at 2019-12-16T21:55:00.000 UTC (T0+1281.527 s) as follows: Band model 1 (alpha=-1.9, beta=-3.7, Ep=70 keV): 1 s: 2.0e-08 erg cm^-2 10 s: 1.0e-07 erg cm^-2 Band model 2 (alpha=-1.0, beta=-2.3, Ep=230 keV): 1 s: 3.5e-08 erg cm^-2 10 s: 1.7e-07 erg cm^-2 Band model 3 (alpha=-0.0, beta=-1.5, Ep=1000 keV): 1 s: 1.5e-07 erg cm^-2 10 s: 5.6e-07 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. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26570 SUBJECT: LIGO/Virgo S191216ap: Updated Source Classification DATE: 19/12/23 18:27:02 GMT FROM: Brandon Piotrzkowski at U of Wisconsin-Milwaukee The LIGO Scientific Collaboration and the Virgo Collaboration report: We have conducted further analysis of the LIGO Hanford Observatory (H1) and Virgo Observatory (V1) data around the time of the compact binary merger (CBC) candidate S191216ap (GCN Circular 26454). Assuming the candidate is astrophysical, the updated parameter estimation based classification of the GW signal, in order of descending probability, is BBH (>99%), MassGap (<1%), Terrestrial (<1%), BNS (<1%), or NSBH (<1%). For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo Public Alerts User Guide . [1] Veitch et al. PRD 91, 042003 (2015) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26605 SUBJECT: LIGO/Virgo S191216ap: Two candidate counterparts from UKIRT/WFCAM z-band observations DATE: 19/12/28 16:40:33 GMT FROM: Graham P Smith at U of Birmingham G. P. Smith (Birmingham), M. Nicholl (Birmingham), K. Sharon (Michigan), M. Bianconi (Birmingham), W. P. Varricatt (UKIRT), S. Benigni (UKIRT), and E. J. Ridley (Birmingham) report on behalf of the Gravitationally Lensed Gravitational Wave Hunters: As part of our search for strongly-lensed gravitational waves and their electromagnetic counterparts, we observed a contiguous area of 0.75 square degrees within the sky localization of the gravitational wave trigger S191216ap (GCN #26454) with the WFCAM instrument on UKIRT through the z-band. The observations were centered on the position of the HAWC sub-threshold detection of gamma-ray flux reported by Martinez-Castellanos (GCN #26472), and encompassed the full extent of their 68% confidence region. The observations comprise two epochs: Epoch Date(UT) Start(UT) End(UT) Airmass FWHM(arcsec) 1 2019-12-20 04:45:21 05:45:57 1.3-1.7 1.2-1.6 2 2019-12-21 04:31:26 05:43:34 1.3-1.8 1.6-1.8 We estimate that Epoch 1 reaches a 5 sigma point source sensitivity of AB~21.5. Epoch 2 is less sensitive than Epoch 1, with noticeable variations in Epoch 2 between the four observations required to achieve contiguous coverage with WFCAM. A preliminary comparison of Epoch 1 with templates derived from Pan-STARRS1 data (nominal sensitivity of AB=22.3) identified two candidate transient sources. Neither source is known to the Transient Name Server, and Minor Planet Center. The celestial coordinates and estimated z-band apparent AB magnitudes of these two candidates are: Name RA(J2000) Dec(J2000) AB(Epoch1) AB(Epoch2) GLGWc19a 21:32:45.50 +05:19:58.0 20.8+/-0.1 ~22 GLGWc19b 21:35:20.11 +04:55:19.8 20.6+/-0.1 >20(tentative) Neither source is associated with an obvious candidate gravitational lens (i.e. massive galaxy, group or cluster) to the depth of the PS1 data. However, GLGWc19a is 7 arcsec West, 1 arcsec North of the center of an edge-on disk galaxy (possible host?) that is located at 21:32:45.97 +5:19:57.0. These sources are observable at Airmass<2 for ~30 minutes following the end of evening twilight in the Northern Hemisphere in the next few nights, before becoming unobservable through the winter months. We therefore encourage urgent follow-up observations of GLGWc19a, GLGWc19b and the candidate host galaxy adjacent to GLGWc19a. We thank the Director of UKIRT, Klaus Hodapp, for quickly approving our urgent DDT proposal. We are also grateful to Mike Irwin for kindly expediting the processing of our data at Cambridge Astronomy Survey Unit (CASU). This circular is citable. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26835 SUBJECT: LIGO/Virgo S191216ap: Upper limits from Konus-Wind observations DATE: 20/01/21 08:46:32 GMT FROM: Anna Ridnaia at Ioffe Institute A. Ridnaia, S. Golenetskii, R.Aptekar, D. Frederiks, M. Ulanov, D. Svinkin, A. Tsvetkova, A. Lysenko, and T. Cline, on behalf of the Konus-Wind team, report: Konus-Wind (KW) was observing the whole sky at the time of the LIGO/Virgo event S191216ap (2019-12-16 21:33:38.473 UTC, hereafter T0; LIGO/Virgo Collaboration GCN Circ. 26454). No triggered KW GRBs happened ~14 days before and ~1 day after T0. The closest waiting-mode GRB was observed ~29 hours after T0. Using waiting-mode data within the interval T0 +/- 100 s, we found no significant (> 5 sigma) excess over the background in both KW detectors on temporal scales from 2.944 s to 100 s. We estimate an upper limit (90% conf.) on the 20 - 1500 keV fluence to 8.1x10^-7 erg/cm^2 for a burst lasting less than 2.944 s and having a typical KW short GRB spectrum (an exponentially cut off power law with alpha =-0.5 and Ep=500 keV). For a typical long GRB spectrum (the Band function with alpha=-1, beta=-2.5, and Ep=300 keV), the corresponding limiting peak flux is 2.4x10^-7 erg/cm^2/s (20 - 1500 keV, 2.944 s scale). All the quoted values are preliminary.