J-GEM Follow-Up Observations to Search for an Optical Counterpart of The First Gravitational Wave Source GW150914

J-GEM Follow-Up Observations to Search for an Optical Counterpart of The First Gravitational Wave Source GW150914

Tomoki Morokuma11affiliation: Institute of Astronomy, Graduate School of Science, University of Tokyo, 2-21-1, Osawa, Mitaka, Tokyo 181-0015, Japan    Masaomi Tanaka22affiliation: National Astoronomical Observatory of Japan, Mitaka, Tokyo 181-8588, Japan    Yuichiro Asakura33affiliation: Institute for Space-Earth Environmental Research, Nagoya University, Chikusa-ku, Nagoya 464-8601, Japan    Fumio Abe33affiliation: Institute for Space-Earth Environmental Research, Nagoya University, Chikusa-ku, Nagoya 464-8601, Japan    Paul J. Tristram44affiliation: Mt. John University Observatory, Lake Tekapo 8770, New Zealand    Yousuke Utsumi55affiliation: Hiroshima Astrophysical Science Center, Hiroshima University, Hiroshima 739-8526, Japan    Mamoru Doi11affiliation: Institute of Astronomy, Graduate School of Science, University of Tokyo, 2-21-1, Osawa, Mitaka, Tokyo 181-0015, Japan    Kenta Fujisawa66affiliation: The Research Institute of Time Studies, Yamaguchi University, Yamaguchi 753-8511, Japan    Ryosuke Itoh77affiliation: Department of Physical Science, Hiroshima University, Hiroshima 739-8526, Japan    Yoichi Itoh88affiliation: Nishi-Harima Astronomical Observatory, University of Hyogo, Hyogo 679-5313, Japan    Koji S. Kawabata55affiliation: Hiroshima Astrophysical Science Center, Hiroshima University, Hiroshima 739-8526, Japan    Nobuyuki Kawai99affiliation: Department of Physics, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8551, Japan    Daisuke Kuroda1010affiliation: Okayama Astrophysical Observatory, National Astronomical Observatory of Japan, Asakuchi, Okayama 719-0232, Japan    Kazuya Matsubayashi1111affiliation: Department of Astronomy, Kyoto University, Kitashirakawa-Oiwake, Kyoto 606-8502, Japan    Kentaro Motohara11affiliation: Institute of Astronomy, Graduate School of Science, University of Tokyo, 2-21-1, Osawa, Mitaka, Tokyo 181-0015, Japan    Katsuhiro L. Murata1212affiliation: Department of Particle and Astrophysical Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan    Takahiro Nagayama1313affiliation: Graduate School of Science and Engineering, Kagoshima University, Kagoshima 890-0065, Japan    Kouji Ohta1111affiliation: Department of Astronomy, Kyoto University, Kitashirakawa-Oiwake, Kyoto 606-8502, Japan    Yoshihiko Saito99affiliation: Department of Physics, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8551, Japan    Yoichi Tamura11affiliation: Institute of Astronomy, Graduate School of Science, University of Tokyo, 2-21-1, Osawa, Mitaka, Tokyo 181-0015, Japan    Nozomu Tominaga1414affiliation: Department of Physics, Faculty of Science and Engineering, Konan University, Kobe, Hyogo 658-8501, Japan 1515affiliation: Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo, Kashiwa, Chiba 277-8583, Japan    Makoto Uemura55affiliation: Hiroshima Astrophysical Science Center, Hiroshima University, Hiroshima 739-8526, Japan    Kenshi Yanagisawa1010affiliation: Okayama Astrophysical Observatory, National Astronomical Observatory of Japan, Asakuchi, Okayama 719-0232, Japan    Yoichi Yatsu99affiliation: Department of Physics, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8551, Japan    Michitoshi Yoshida55affiliation: Hiroshima Astrophysical Science Center, Hiroshima University, Hiroshima 739-8526, Japan tmorokuma@ioa.s.u-tokyo.ac.jp
Abstract

We present our optical follow-up observations to search for an electromagnetic counterpart of the first gravitational wave source GW150914 in the framework of the Japanese collaboration for Gravitational wave ElectroMagnetic follow-up (J-GEM), which is an observing group utilizing optical and radio telescopes in Japan, as well as those in New Zealand, China, South Africa, Chile, and Hawaii. We carried out a wide-field imaging survey with Kiso Wide Field Camera (KWFC) on the 1.05-m Kiso Schmidt telescope in Japan and a galaxy-targeted survey with Tripole5 on the B&C 61-cm telescope in New Zealand. Approximately 24 deg regions in total were surveyed in -band with KWFC and 18 nearby galaxies were observed with Tripole5 in -, -, and -bands 4-12 days after the gravitational wave detection. Median depths are  mag for the KWFC data and  mag,  mag, and  mag for the Tripole5 data. Probability for a counterpart to be in the observed area is 1.2% in the initial skymap and 0.1% in the final skymap. We do not find any transient source associated to an external galaxy with spatial offset from its center, which is consistent with the local supernova rate. We summarize future prospects and ongoing efforts to pin down electromagnetic counterparts of binary black hole mergers as well as neutron star mergers.

\SetRunningHead

J-GEM Observations for GW150914 Usage of pasj00.cls

\KeyWords

gravitational waves — black hole physics — surveys — methods: observational — binaries: close

1 Introduction

A new generation of gravitational-wave (GW) detectors, Advanced LIGO (Abbott et al., 2016a), Advanced Virgo (Acernese et al., 2015), and KAGRA (Somiya, 2012), are designed to detect GWs from mergers of neutron stars (NSs) and black holes (BHs). These new detectors are much more sensitive than ever; with the design sensitivity, the horizon distance will reach  Mpc for NS-NS mergers and a few Gpc for BH-NS or BH-BH mergers and many detections of GW events per year are expected (Abbott et al., 2016e).

Detections of electromagnetic (EM) counterparts are essential to study their astrophysical properties and environments. However, since positional localization only with the GW detectors is not accurate, which is larger than deg during their early observing run (Kasliwal & Nissanke (2014); Singer et al. (2014)) and a few 10 deg even in the LIGO-Virgo-KAGRA era (Nissanke et al., 2013; Kelley et al., 2013), it is a big challenge to identify the EM counterparts. To guide surveys for the EM identification, various kinds of EM signals have been theoretically studied over a wide wavelength range, from radio (Nakar & Piran, 2011), infrared, optical, and ultraviolet (Li & Paczyński, 1998; Kulkarni, 2005; Metzger et al., 2010; Tanaka & Hotokezaka, 2013), X-ray (Nakamura et al., 2014; Metzger & Piro, 2014), and to gamma-ray (e.g., short gamma-ray burst; Metzger & Berger (2012)). Consequently, we have organized a group to carry out systematic follow-up observations of GW sources using Japanese facilities called “Japanese collaboration for GW EM follow-up (J-GEM)” as part of a larger worldwide EM follow-up effort.

Recently Advanced LIGO reported the first detection of the GW event (GW150914, Abbott et al. (2016c)). The signal was detected at 09:50:45 on 2015 September 14 UT, 4 days before the official start of the first observing run (O1) and an alert was delivered via GCN Notices in a machine-readable way at 03:12:12 and by an e-mail manually at 05:39:44 on 2015 September 16 UT. The waveform indicates that the source of the GWs is a merger of two BHs, whose masses are estimated to be and , and that the luminosity distance is Mpc (The LIGO Scientific Collaboration & the Virgo Collaboration, 2016). The position of the source is localized to 590 deg (90 % probability). We note that, ath the time of the initial alert, a classification of this GW source was not shared with the EM observers and the BH-BH nature was informed after our observations presented in this Letter.

To search for an EM counterpart of GW150914, extensive EM follow-up observations have been performed following the alert Abbott et al. (2016d); Abbott et al. (2016b)). In this Letter, we report optical follow-up observations for GW150914 by the J-GEM collaboration. We refer to a skymap promptly produced with LALInference Burst (LIB; Lynch et al. (2015)) as the initial skymap and to the most accurate LALInference (Veitch et al., 2015) skymap distributed on 2016 January 13 as the final skymap. All the magnitudes shown in this Letter are in the AB system.

2 J-GEM Observations for GW150914

J-GEM has observing facilities from radio to optical as listed in Table J-GEM Follow-Up Observations to Search for an Optical Counterpart of The First Gravitational Wave Source GW150914. They are nicely distributed all over the Earth in terms of the longitude of the sites. Among them, we utilized two telescopes to carry out two types of optical follow-up observations for GW150914: one is an imaging survey with a wide-field imaging camera, Kiso Wide Field Camera (KWFC; Sako et al. (2012)) mounted to the 1.05-m Kiso Schmidt telescope in Japan and the other is galaxy-targeted observations of nearby potential host galaxies of the GW source with Tripole5 on the 61-cm Boller & Chivens (B&C) Telescope at the Mt. John University Observatory in New Zealand. Most of the high probability regions are in the southern hemisphere and are difficult to observe with most of our observing facilities. Subaru Hyper Suprime-Cam (HSC; Miyazaki et al. (2012)), which has the widest field-of-view among 8m-class telescopes, was not available after the alert until early October.

2.1 Kiso KWFC Observations

KWFC is a wide-field optical imaging camera on the 1.05-m Kiso Schmidt telescope. The camera consists of eight 2k4k CCDs and the total field-of-view is  deg  deg.

The KWFC observations were carried out on 2015 September 18, 4.4 days after the GW detection. We took 180-second exposures for five continuous field-of-views, approximately deg in total (Morokuma et al., 2016). The observed area is shown in Figure 1 and details of the observations are summarized in Table J-GEM Follow-Up Observations to Search for an Optical Counterpart of The First Gravitational Wave Source GW150914. High probability region in the skymap visible from the site during the night are almost towards the Sun and the target fields are observable only at very low elevation (high airmass: , where is the zenith distance) right before sunrise and during the astronomical twilight. Therefore, we chose the -band filter to avoid high sky background due to the Sun as much as possible.

The total probability of the regions observed with KWFC to include the GW source was initially 1.2% but turned out to be % in the final skymap. The observed regions are partly overlapped with regions covered by Pan-STARRS (PS1; Smartt et al. (2016)) and MASTER-NET (Lipunov et al., 2016)111http://master.sai.msu.ru/static/G184098/G184098_4.png.

The data reduction procedure basically follows that of the supernova (SN) survey with KWFC (KISS; Morokuma et al. (2014)). The limiting magnitudes are approximately 19 mag for the first four images and as shallow as 16.2 mag for the last image due to the twilight. For each of the fully reduced images, we applied an image subtraction method (hotpants222http://www.astro.washington.edu/users/becker/v2.0/hotpants.html) with deeper archival Sloan Digital Sky Survey (SDSS) images taken several years ago as references. Then, we extract transient objects with positive fluxes (2.5 , 5 pixel connection) in the subtracted images with SExtractor (Bertin & Arnouts, 1996).

2.2 B&C 61-cm Tripole5 Observations

Tripole5 is an optical camera on the B&C 61cm telescope capable of taking images in  arcmin  arcmin field-of-view in -, -, and -bands, simultaneously.

The observations are started on 2015 September 20, 6.3 days after the GW detection. We observed 18 nearby galaxies in the high probability region of the southern hemisphere as shown in Figure 1 and Table J-GEM Follow-Up Observations to Search for an Optical Counterpart of The First Gravitational Wave Source GW150914. Two to six 120-sec frames were taken per galaxy in -, -, and -bands on 2015 September 20, 21, 24, and 26. The observed galaxies are selected from the Gravitational Wave Galaxy Catalogue (GWGC; White et al. (2011)) based on the initial skymap and are closer than 100 Mpc so that an EM counterpart of an NS-NS merger could be detected. All the galaxies observed are located within the  deg of the overlapped localization region (90% confidence) of GW150914 and GW150914-GBM, detected with Gamma-ray Burst Monitor (GBM) onboard the Fermi Gamma-ray Space Telescope (Connaughton et al., 2016).

The total probabilities in the initial and final skymaps are % although the distance  Mpc is farther than the maximum distances to the galaxies by a factor of . The number of the observed galaxies is about 4% of the galaxies in the GWGC catalog within the 90% probability region.

The data are reduced in a standard manner using IRAF. Zeropoint magnitudes in the and -bands are determined relative to the , , and -band magnitudes of objects in the USNO-B1.0 catalog (Monet et al., 2003) using the conversion equations in Fukugita et al. (1996). Medians of the limiting magnitudes are mag, mag, and mag. Object catalogs for the Tripole5 images are created using SExtractor.

Figure 1: Final skymap (LALInference) for the GW150914 localization and the observed regions with KWFC (left) and Tripole5 (right). The color map is shown in unit of probability per HEALPix (Górski et al., 2005) pixel of , corresponding to about 47 arcmin. The KWFC field-of-views are shown in box and the area observed with Tripole5 are shown in dots.

3 Results & Discussion

For the KWFC data, radial profiles and SDSS classifications (star/galaxy separation based on probPSF information available in the SDSS database) of all of the transient objects are used to extract extragalactic transients. Known asteroids are also checked with MPChecker and removed from the transient catalog. For the Tripole5 data, the object catalog in the entire observed field of each target galaxy is first compared with the USNO-B1.0 catalog. There remain some objects without any counterparts in the USNO-B1.0 catalog and they are visually inspected by comparing the Tripole5 images with the Digitized Sky Survey images.

In these procedures described above, we find no extragalactic transient object with a spatial offset from its host galaxy although we detect variability at centers of several external galaxies (including PS15cek described below). Given the survey areas, depths of the data, and the measured volumetric SN rates in the local universe (Blanc et al. (2004) for Type Ia SNe and Li et al. (2011) for Core-Collapse SNe), expected number of SNe is smaller than unity. This is consistent with the result that we do not find any SN candidate.

Among transient objects discovered and reported by other projects so far (PS1 by Smartt et al. (2016); UVOT on the Swift satellite by Evans et al. (2016); La Silla - QUEST by Rabinowitz et al. (2015), and iPTF by Singer et al. (2015) and Kasliwal et al. (2016)) four transients are within the regions observed with KWFC; PS15cej, PS15cek, PS15ckf, and PS15dft (Table J-GEM Follow-Up Observations to Search for an Optical Counterpart of The First Gravitational Wave Source GW150914). All these PS1 transients were discovered in early October 2015, while our KWFC data were taken in September 2015. PS15cek is a known AGN (2MFGC 07447; Véron-Cetty & Véron (2001)) at , and the variability is also detected in our KWFC images compared with the past SDSS data. We do not detect the other three objects, i.e., two SNe (PS15cej and PS15ckf) and one cataclysmic variable star (PS15dft or ASASSN-15se), but the non-detection of variability is not surprising since these explosions and flare are likely to occur after our observations in September (Smartt et al., 2016).

Several theoretical scenarios about EM counterparts of BH-BH mergers and their emissions are available. Nakamura et al. (2016) calculated an expected optical emission from almost the same system as GW150914. In their model, Eddington luminosity of a  M BH in dense interstellar medium may have brightness of about 26 mag if the emission is radiated mainly in the optical wavelength at a similar distance to GW150914 ( Mpc), which can be detected with 8m-class telescopes and instruments. Yamazaki et al. (2016) and Morsony et al. (2016) predict a wide range of EM emissions from GW150914 under an assumption that GW150914-GBM (Connaughton et al., 2016) is associated with the GW150914 (Loeb, 2016). They suggest that an optical counterpart is detectable with 8-m class telescopes within 1 or a few days after the GW event and that earlier emission within several hours after the event can be detected with smaller aperture (2-4 m) telescopes.

These theoretical models indicate that wide-field surveys with 8m-class telescopes and instruments such as Subaru HSC or Large Synoptic Survey Telescope (LSST; LSST Science Collaboration et al. (2009)) is the best strategy to detect an optical counterpart of a GW event like GW150914. If a similar event to GW150914 occurs at a closer distance, an optical counterpart could be detectable with 1-2-m class telescopes. Although selecting the counterpart from a huge amount of imaging data is challenging, several intensive works have been done. Implementation of machine-learning techniques for reducing real-to-bogus ratios with wide-field imaging data have been done in several projects (e.g., Bloom et al. (2012); Brink et al. (2013)). Among the J-GEM instruments, machine-learning approach for effective discoveries of transient objects is being done for Subaru HSC data (Morii et al., 2016). Effective classification trial for many transient objects (Kessler et al., 2010) by adding realistic theoretical models for GW EM counterparts including NS-NS merger (see the review by Tanaka (2016)) will also help us to identify the EM counterpart in near future.

{ack}

This work is supported by MEXT Grant-in-Aid for Scientific Research on Innovative Areas “New Developments in Astrophysics Through Multi-Messenger Observations of Gravitational Wave Sources” (24103003) and its Koubo Researches (25103503, 15H00788, 15H00774). This work is also supported by JSPS (15H02075). This study utilizes the archival images from the Sloan Digital Sky Survey and those from the Digitized Sky Surveys. Full acknowledgments can be found at http://www.sdss.org/collaboration/credits.html and https://archive.stsci.edu/dss/acknowledging.html, respectively.

References

  • Abbott et al. (2016a) Abbott, B. P., et al. 2016a, Physical Review Letters, 116, 131103
  • Abbott et al. (2016b) Abbott, B. P., et al. 2016b, ArXiv e-prints, arXiv:1602.08492
  • Abbott et al. (2016c) Abbott, B. P., et al. 2016c, Physical Review Letters, 116, 061102
  • Abbott et al. (2016d) Abbott, B. P., et al. 2016d, ArXiv e-prints, arXiv:1604.07864
  • Abbott et al. (2016e) Abbott, B. P., et al. 2016e, ArXiv e-prints, arXiv:1602.03842
  • Acernese et al. (2015) Acernese, F., et al. 2015, Classical and Quantum Gravity, 32, 024001
  • Akitaya et al. (2014) Akitaya, H., et al. 2014, \procspie, 9147, 91474O
  • Bertin & Arnouts (1996) Bertin, E., & Arnouts, S. 1996, A&AS, 117, 393
  • Blanc et al. (2004) Blanc, G., et al. 2004, A&A, 423, 881
  • Bloom et al. (2012) Bloom, J. S., et al. 2012, PASP, 124, 1175
  • Brink et al. (2013) Brink, H., Richards, J. W., Poznanski, D., Bloom, J. S., Rice, J., Negahban, S., & Wainwright, M. 2013, MNRAS, 435, 1047
  • Connaughton et al. (2016) Connaughton, V., et al. 2016, ArXiv e-prints, arXiv:1602.03920
  • Evans et al. (2016) Evans, P. A., et al. 2016, MNRAS, arXiv:1602.03868
  • Fukugita et al. (1996) Fukugita, M., Ichikawa, T., Gunn, J. E., Doi, M., Shimasaku, K., & Schneider, D. P. 1996, AJ, 111, 1748
  • Górski et al. (2005) Górski, K. M., Hivon, E., Banday, A. J., Wandelt, B. D., Hansen, F. K., Reinecke, M., & Bartelmann, M. 2005, ApJ, 622, 759
  • Kasliwal & Nissanke (2014) Kasliwal, M. M., & Nissanke, S. 2014, ApJL, 789, L5
  • Kasliwal et al. (2016) Kasliwal, M. M., et al. 2016, ArXiv e-prints, arXiv:1602.08764
  • Kawabata et al. (2008) Kawabata, K. S., et al. 2008, \procspie, 7014, 70144L
  • Kelley et al. (2013) Kelley, L. Z., Mandel, I., & Ramirez-Ruiz, E. 2013, Phys. Rev. D, 87, 123004
  • Kessler et al. (2010) Kessler, R., et al. 2010, PASP, 122, 1415
  • Konishi et al. (2015) Konishi, M., et al. 2015, PASJ, 67, 4
  • Kotani et al. (2005) Kotani, T., et al. 2005, Nuovo Cimento C Geophysics Space Physics C, 28, 755
  • Kulkarni (2005) Kulkarni, S. R. 2005, arXiv:astro-ph/0510256, arXiv:astro-ph/0510256
  • Li & Paczyński (1998) Li, L.-X., & Paczyński, B. 1998, ApJL, 507, L59
  • Li et al. (2011) Li, W., Chornock, R., Leaman, J., Filippenko, A. V., Poznanski, D., Wang, X., Ganeshalingam, M., & Mannucci, F. 2011, MNRAS, 412, 1473
  • Lipunov et al. (2016) Lipunov, V., et al. 2016, GRB Coordinates Network, 18903
  • Loeb (2016) Loeb, A. 2016, ArXiv e-prints, arXiv:1602.04735
  • LSST Science Collaboration et al. (2009) LSST Science Collaboration, et al. 2009, ArXiv e-prints, arXiv:0912.0201
  • Lynch et al. (2015) Lynch, R., Vitale, S., Essick, R., Katsavounidis, E., & Robinet, F. 2015, ArXiv e-prints, arXiv:1511.05955
  • Metzger & Berger (2012) Metzger, B. D., & Berger, E. 2012, ApJ, 746, 48
  • Metzger & Piro (2014) Metzger, B. D., & Piro, A. L. 2014, MNRAS, 439, 3916
  • Metzger et al. (2010) Metzger, B. D., et al. 2010, MNRAS, 406, 2650
  • Miyazaki et al. (2012) Miyazaki, S., et al. 2012, \procspie, 8446, 84460Z
  • Monet et al. (2003) Monet, D. G., et al. 2003, AJ, 125, 984
  • Morii et al. (2016) Morii, M., et al. 2016, submitted to PASJ
  • Morokuma et al. (2014) Morokuma, T., et al. 2014, PASJ, 66, 114
  • Morokuma et al. (2016) Morokuma, T., et al. 2016, GRB Coordinates Network, 19017
  • Morsony et al. (2016) Morsony, B. J., Workman, J. C., & Ryan, D. M. 2016, ArXiv e-prints, arXiv:1602.05529
  • Nagashima et al. (1999) Nagashima, C., et al. 1999, in Star Formation 1999, ed. T. Nakamoto, 397-398
  • Nagayama et al. (2003) Nagayama, T., Nagashima, C., Nakajima, Y., Nagata, T., Sato, S., Nakaya, H., Yamamuro, T., Sugitani, K., & Tamura, M. 2003, \procspie, 4841, 459-464
  • Nakamura et al. (2014) Nakamura, T., Kashiyama, K., Nakauchi, D., Suwa, Y., Sakamoto, T., & Kawai, N. 2014, ApJ, 796, 13
  • Nakamura et al. (2016) Nakamura, T., Nakano, H., & Tanaka, T. 2016, ArXiv e-prints, arXiv:1601.00356
  • Nakar & Piran (2011) Nakar, E., & Piran, T. 2011, Nature, 478, 82
  • Nissanke et al. (2013) Nissanke, S., Kasliwal, M., & Georgieva, A. 2013, ApJ, 767, 124
  • Oshima et al. (2012) Oshima, T., et al. 2012, in IEEE Trans. Appl. Supercond, Vol. 23, Ground-based and Airborne Instrumentation for Astronomy IV, 2101004-1-2101004-4
  • Rabinowitz et al. (2015) Rabinowitz, D., Baltay, C., Ellman, N., & Nugent, P. 2015, GRB Coordinates Network, 18347
  • Sakimoto et al. (2012) Sakimoto, K., et al. 2012, \procspie, 8446, 844673
  • Sako et al. (2012) Sako, S., et al. 2012, \procspie, 8446, 84466L
  • Sako et al. (2008) Sako, T., et al. 2008, Experimental Astronomy, 22, 51
  • Singer et al. (2014) Singer, L. P., et al. 2014, ApJ, 795, 105
  • Singer et al. (2015) Singer, L. P., et al. 2015, GRB Coordinates Network, 18337
  • Smartt et al. (2016) Smartt, S. J., et al. 2016, ArXiv e-prints, arXiv:1602.04156
  • Somiya (2012) Somiya, K. 2012, Classical and Quantum Gravity, 29, 124007
  • Tanaka (2016) Tanaka, M. 2016, submitted to Advances in Astronomy
  • Tanaka & Hotokezaka (2013) Tanaka, M., & Hotokezaka, K. 2013, ApJ, 775, 113
  • The LIGO Scientific Collaboration & the Virgo Collaboration (2016) The LIGO Scientific Collaboration, & the Virgo Collaboration. 2016, ArXiv e-prints, arXiv:1602.03840
  • Veitch et al. (2015) Veitch, J., et al. 2015, Phys. Rev. D, 91, 042003
  • Véron-Cetty & Véron (2001) Véron-Cetty, M.-P., & Véron, P. 2001, A&A, 374, 92
  • White et al. (2011) White, D. J., Daw, E. J., & Dhillon, V. S. 2011, Classical and Quantum Gravity, 28, 085016
  • Yamazaki et al. (2016) Yamazaki, R., Asano, K., & Ohira, Y. 2016, ArXiv e-prints, arXiv:1602.05050
  • Yanagisawa et al. (2010) Yanagisawa, K., Kuroda, D., Yoshida, M., Shimizu, Y., Nagayama, S., Toda, H., Ohta, K., & Kawai, N. 2010, in American Institute of Physics Conference Series, Vol. 1279, American Institute of Physics Conference Series, ed. N. Kawai & S. Nagataki, 466-468
  • Yanagisawa et al. (2014) Yanagisawa, K., et al. 2014, \procspie, 9147, 91476D
\tbl

J-GEM Telescopes in an order of longitude. Site (telescope) [m] Location Instrument FoV Pixel Scale Note Mt. Johns (B&C 61cm) 0.61 170.47 E, 43.40 S, 1029 Tripole5 \timeform4.’2 \timeform6.’2 0.17 (1) Mt. Johns (MOA-II) 1.8 170.47 E, 43.40 S, 1029 MOA-cam3 [1] \timeform1.31D \timeform1.64D 0.58 (3) Akeno (MITSuME) 0.5 138.48 E, 35.79 N, 900 ( imager) \timeform27.8’ \timeform27.8’ 1.63 (1) Kiso (Kiso Schimidt) 1.05 137.63 E, 35.79 N, 1130 KWFC [2] \timeform2.2D \timeform2.2D 0.946 (3) Nishi-Harima (Nayuta) 2.0 134.34 E, 35.03 N, 449 MINT \timeform10.9’ \timeform10.9’ 0.32 (1) Okayama, OAO (Kyoto-3.8m) 3.8 133.60 E, 34.58 N, 343 KOOLS-IFU \timeform14” 1.14 (2) Okayama, OAO (OAO 188cm) 1.88 133.59 E, 34.58 N, 371 KOOLS-IFU \timeform30” 2.34 (2) Okayama, OAO (OAO 91cm) 0.9 133.59 E, 34.58 N, 364 OAO-WFC [3] \timeform28.4’ \timeform28.4’ 1.67 (1) Okayama, OAO (MITSuME) 0.5 133.59 E, 34.58 N, 358 ( imager) [4],[5] \timeform26.9’ \timeform26.9’ 1.52 (1) Higashi-Hiroshima (Kanata) 1.5 132.78 E, 34.38 N, 511 HOWPol [6] \timeform15’ 0.30 (1) Higashi-Hiroshima (Kanata) 1.5 132.78 E, 34.38 N, 511 HONIR [7],[8] \timeform10’ \timeform 10’ 0.30 (1) Yamaguchi (Yamaguchi) 131.56 E, 34.22 N, 166 6-8 GHz Receiver - 4-5 arcmin (1) Tibet (HinOTORI) 0.5 80.03 E, 32.31 N, 5130 ( imager) \timeform24’ \timeform24’ 0.68 (1) Sutherland, SAAO (IRSF) 1.4 20.81 E, 32.38 S, 1761 SIRIUS [9],[10] \timeform7.7’ \timeform7.7’ 0.45 (1) Pampa la Bola (ASTE) 10 67.70 W, 22.97 S, 4862 ASTECAM [11] \timeform8.1’  20-30 (1) Chajnantor, TAO (miniTAO) 1.04 67.74 W, 22.99 S, 5640 ANIR [12] \timeform5.1’ \timeform 5.1’ 0.298 (1) Mauna Kea, MKO (Subaru) 8.2 155.48 W, 19.83 N, 4139 HSC [13] \timeform1.5D 0.168 (3) {tabnote} References for instruments; [1]: Sako et al. (2008), [2]: Sako et al. (2012), [3]: Yanagisawa et al. (2014), [4]: Kotani et al. (2005), [5]: Yanagisawa et al. (2010), [6]: Kawabata et al. (2008), [7]: Akitaya et al. (2014), [8]: Sakimoto et al. (2012), [9]: Nagashima et al. (1999), [10]: Nagayama et al. (2003), [11]: Oshima et al. (2012), [12]: Konishi et al. (2015), [13]: Miyazaki et al. (2012).
a: diameter of telescope primary mirror.
b: longitude and latitude in degrees, and height in meters.
c: pixel scale is in arcsec pixel.
d: to be operated.
e: radio or submillimeter telescopes.
f: (1) galaxy-targeted; (2) integral field spectroscopy; (3) wide-field survey.

\tbl

Summary of Kiso KWFC Observations. UT MJD Field RA Dec Filter 2015-09-18 19:06:02 57283.7969 KT009891 09:05:35.52 +10:27:00.0 180 19.2 2015-09-18 19:11:37 57283.8008 KT009892 09:14:32.16 +10:27:00.0 180 18.9 2015-09-18 19:16:59 57283.8045 KT009893 09:23:28.80 +10:27:00.0 180 18.9 2015-09-18 19:22:22 57283.8083 KT009894 09:32:25.44 +10:27:00.0 180 18.9 2015-09-18 19:34:29 57283.8167 KT009895 09:41:22.08 +10:27:00.0 180 16.3 {tabnote} a: time starting the exposures. b: MJDs of the middle of the exposures. c: Exposure time for each field is in seconds.

\tbl

Summary of B&C 61cm telescope Tripole5 Observations. Galaxy RA Dec  [Mpc] Filter 2015-09-20 2015-09-21 2015-09-24 2015-09-26 ESO034-012 06:43:30.8 72:35:41 - ESO058-014 06:46:36.1 70:36:54 - ESO058-023 07:04:45.5 71:00:59 - ESO059-023 07:56:06.1 68:16:41 - ESO060-010 08:38:36.7 67:56:11 - ESO060-011 08:42:43.0 67:48:54 ESO060-018 08:56:40.5 67:52:13 - ESO089-009 08:05:09.0 67:35:12 ESO089-015 08:18:08.1 67:34:37 - ESO089-016 08:18:23.4 67:36:40 ESO090-011 08:58:18.5 65:22:03 ESO126-023 09:37:51.2 62:09:04 - ESO126-024 09:38:29.1 61:49:47 NGC 2150 05:55:46.3 69:33:39 NGC 2187 06:03:48.5 69:35:00 NGC 2187A 06:03:44.2 69:35:18 NGC 2442 07:36:23.8 69:31:51 - NGC 2466 07:45:16.0 71:24:38 {tabnote} a: The coordinates of the center of the galaxy and the distances to the galaxies are derived from the GWGC (White et al., 2011).
b: Exposure time on each date for each galaxy is in seconds.

\tbl

Transients Reported in Other Papers in Our Survey Fields. Name RA Dec Reference Nature Disc ID Expl. J-GEM note PS15cej 09:35:19.41 10:11:50.7 Smartt et al. (2016) SN Ia 2015-10-02 2015-10-10 2015-09-22 KWFC before Expl. PS15cek 09:36:41.04 10:14:16.2 Smartt et al. (2016) AGN 2015-10-02 - - KWFC - PS15ckf 09:45:57.71 09:58:31.4 Smartt et al. (2016) SN II 2015-10-03 2015-10-20 2015-09-27 KWFC before Expl. PS15dft 09:33:09.38 10:28:02.2 Smartt et al. (2016) CV 2015-10-23 - - KWFC - {tabnote} a: PS1 discovery date.
b: Date of PS1 spectroscopic identification.
c: Explosion date based on the spectroscopic phase.

Comments 0
Request Comment
You are adding the first comment!
How to quickly get a good reply:
  • Give credit where it’s due by listing out the positive aspects of a paper before getting into which changes should be made.
  • Be specific in your critique, and provide supporting evidence with appropriate references to substantiate general statements.
  • Your comment should inspire ideas to flow and help the author improves the paper.

The better we are at sharing our knowledge with each other, the faster we move forward.
""
The feedback must be of minimum 40 characters and the title a minimum of 5 characters
   
Add comment
Cancel
Loading ...
375770
This is a comment super asjknd jkasnjk adsnkj
Upvote
Downvote
""
The feedback must be of minumum 40 characters
The feedback must be of minumum 40 characters
Submit
Cancel

You are asking your first question!
How to quickly get a good answer:
  • Keep your question short and to the point
  • Check for grammar or spelling errors.
  • Phrase it like a question
Test
Test description