IssueNo.121 February2020 ✤✜ s ✓✏ DISTANT EKO ❞✐ ✒✑ The Kuiper Belt Electronic Newsletter ✣✢ r Edited by: Joel Wm. Parker [email protected] www.boulder.swri.edu/ekonews CONTENTS News & Announcements ................................. 2 Abstracts of 14 Accepted Papers ........................ 3 Abstract of 1 Submitted Papers .........................14 Conference Information .............................. 15 Newsletter Information .............................. 16 1 NEWS & ANNOUNCEMENTS There were 11 new TNO discoveries announced since the previous issue of Distant EKOs: 2003 UY413, 2014 HX209, 2014 JC92, 2015 KU178, 2016 SH57, 2016 SJ56, 2016 SQ55, 2016 SQ58, 2016 SZ57, 2019 RO4, 2018 MF13 and 12 new Centaur/SDO discoveries: 2012 GT41, 2013 CJ118, 2015 HA197, 2016 SA56, 2016 SU55, 2018 RR2, 2019 CJ3, 2019 GN22, 2019 QQ8, 2019 TL8, 2019 UH12, 2019 UO14 Reclassified objects: 2015 SV20 (SDO → Centaur) 2017 YK3 (Centaur → TNO) 2007 RL314 (TNO → SDO) 2010 RD188 (TNO → SDO) 2003 US292 (SDO → TNO) 2010 PK66 (SDO → TNO) 2014 OL394 (SDO → TNO) 2018 AZ18 (SDO → TNO) Objects recently assigned numbers: 2013 AP183 = (542258) 2013 MY11 = (542889) 2015 TG387 = (541132) Objects recently assigned names: 2007 UK126 = G!k´un||’h`omd´ım`a 2014 GE45 = Zhulong 2014 MU69 = Arrokoth Deleted/Re-identified objects: 2005 JZ185 = 2015 KU178 2010 TF182 = 2015 SO20 2010 TO182 = 2011 UK411 2010 TQ182 = 2014 UM33 2014 CH5 = 2014 DO143 2014 OZ391 = 2015 PN291 2019 CR 2016 GR206 Current number of TNOs: 2416 Current number of Centaurs/SDOs: 1085 Current number of Neptune Trojans: 24 Out of a total of 3525 objects: 670 have measurements from only one opposition 667 of those have had no measurements for more than a year 364 of those have arcs shorter than 10 days (for more details, see: http://www.boulder.swri.edu/ekonews/objects/recov_stats.jpg) 2 PAPERS ACCEPTED TO JOURNALS OSSOS XII: Variability Studies of 65 Trans-Neptunian Objects using the Hyper-Suprime Camera M. Alexandersen1, S.D. Benecchi2, Y.-T. Chen1, M.R. Eduardo1,3, A. Thirouin4, M.E. Schwamb5, M.J. Lehner1,6,7, S.-Y. Wang1, M.T. Bannister8, B.J. Gladman9, S.D.J. Gwyn10, JJ. Kavelaars10,11, J.-M. Petit12, and K. Volk13 1 Institute of Astronomy and Astrophysics, Academia Sinica; 11F of AS/NTU Astronomy-Mathematics Building, No. 1 Roosevelt Rd., Sec. 4, Taipei 10617, Taiwan 2 Planetary Science Institute, 1700 E. Fort Lowell, Suite 106, Tucson, AZ 85719, USA 3 Department of Physical Sciences, University of the Philippines Baguio, Gov. Pack Rd., Baguio City, Benguet, 2600, Philippines 4 Lowell Observatory, 1400 W. Mars Hill Rd., Flagstaff, AZ 86001, USA 5 Gemini Observatory, Northern Operations Center, 670 North A’ohoku Pl., Hilo, HI 96720, USA 6 Department of Physics and Astronomy, University of Pennsylvania, 209 S. 33rd St., Philadelphia, PA 19104, USA 7 Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138, USA 8 Astrophysics Research Centre, School of Mathematics and Physics, Queen’s University Belfast, Belfast BT7 1NN, UK 9 Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1, Canada 10 Herzberg Astronomy and Astrophysics Research Centre, National Research Council of Canada, 5071 W. Saanich Rd., Victoria, British Columbia V9E 2E7, Canada 11 Department of Physics and Astronomy, University of Victoria, Elliott Building, 3800 Finnerty Rd., Victoria, BC V8P 5C2, Canada 12 Institut UTINAM UMR6213, CNRS, Univ. Bourgogne Franche-Comt´e, OSU Theta F-25000 Besan¸con, France 13 Lunar and Planetary Laboratory, University of Arizona, 1629 E. University Blvd., Tucson, AZ 85721, USA We present variability measurements and partial light curves of Trans-Neptunian Objects (TNOs) from a two-night pilot study using Hyper Suprime-Cam (HSC) on the Subaru Telescope (Maunakea, Hawai’i, USA). Subaru’s large aperture (8-m) and HSC’s large field of view (1.77 deg2) allow us to obtain measurements of multiple objects with a range of magnitudes in each telescope pointing. We observed 65 objects with mr = 22.6–25.5 mag in just six pointings, allowing 20–24 visits of each pointing over the two nights. Our sample, all discovered in the recent Outer Solar System Origins Survey (OSSOS), span absolute magnitudes Hr = 6.2–10.8 mag and thus investigates smaller objects than previous light curve projects have typically studied. Our data supports the existence of a correlation between light curve amplitude and absolute magnitude seen in other works, but does not support a correlation between amplitude and orbital inclination. Our sample includes a number of objects from different dynamical populations within the trans-Neptunian region, but we do not find any relationship between variability and dynamical class. We were only able to estimate periods for 12 objects in the sample and found that a longer baseline of observations is required for reliable period analysis. We find that 31 objects (just under half of our sample) have variability ∆mag greater than 0.4 mag during all of the observations; in smaller 1.25 hr, 1.85 hr and 2.45 hr windows, the median ∆mag is 0.13, 0.16 and 0.19 mags, respectively. The fact that variability on this scale is common for small TNOs has important implications for discovery surveys (such as OSSOS or the Large Synoptic Survey Telescope) and color measurements. Published in: The Astrophysical Journal Supplement Series, 244, 19 (2019 September) For preprints, contact [email protected] or on the web at http://adsabs.harvard.edu/abs/2019ApJS..244...19A ................................................... .................................................. 3 Trans-Neptunian Objects Found in the First Four Years of the Dark Energy Survey P. Bernardinelli1, G.M. Bernstein1, M. Sako1, T. Liu1, W. Saunders1,2, T. Khain3, E. Lin3, D.W. Gerdes4,3, D. Brout1, F. Adams4, M. Belyakov1, J. Locke1, K. Franson3, J. Becker3, K. Napier3, L. Markwardt3, J. Annis5, T.M.C. Abbott6, S. Avila7, D. Brooks8, D.L. Burke9,10, A. Carnero Rosell11,12, M. Carrasco Kind13,14, F.J. Castander15,16, L.N. da Costa12,17, J. De Vicente11, S. Desai18, H.T. Diehl5, P. Doel8, S. Everett19, B. Flaugher5, J. Garc´ıa-Bellido7, D. Gruen20,9,10, R.A. Gruendl13,14, J. Gschwend12,17, G. Gutierrez5, D.L. Hollowood19, D.J. James21, M.W.G. Johnson14, M.D. Johnson14, E. Krause22, N. Kuropatkin5, M.A.G. Maia12,17, M. March1, R. Miquel23,24, F. Paz-Chinch´on13,14, A.A. Plazas25, A.K. Romer26, E.S. Rykoff9,10, C. S´anchez1, E. Sanchez11, V. Scarpine5, S. Serrano15,16, I. Sevilla-Noarbe11, M. Smith27, F. Sobreira28,12, E. Suchyta29, M.E.C. Swanson14, G. Tarle3, A.R. Walker6, W. Wester5, and Y. Zhang5 1 Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA 2 Department of Astronomy, Boston University, Boston, MA 02215, USA 3 Department of Physics, University of Michigan, Ann Arbor, MI 48109, USA 4 Department of Astronomy, University of Michigan, Ann Arbor, MI 48109, USA 5 Fermi National Accelerator Laboratory, P. O. Box 500, Batavia, IL 60510, USA 6 Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatory, Casilla 603, La Serena, Chile 7 Instituto de Fisica Teorica UAM/CSIC, Universidad Autonoma de Madrid, 28049 Madrid, Spain 8 Department of Physics & Astronomy, University College London, Gower Street, London, WC1E 6BT, UK 9 Kavli Institute for Particle Astrophysics & Cosmology, P. O. Box 2450, Stanford University, Stanford, CA 94305, USA 10 SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA 11 Centro de Investigaciones Energ´eticas, Medioambientales y Tecnol´ogicas (CIEMAT), Madrid, Spain 12 Laborat´orio Interinstitucional de e-Astronomia - LIneA, Rua Gal. Jos´eCristino 77, Rio de Janeiro, RJ - 20921-400, Brazil 13 Department of Astronomy, University of Illinois at Urbana-Champaign, 1002 W. Green Street, Urbana, IL 61801, USA 14 National Center for Supercomputing Applications, 1205 West Clark St., Urbana, IL 61801, USA 15 Institut d’Estudis Espacials de Catalunya (IEEC), 08034 Barcelona, Spain 16 Institute of Space Sciences (ICE, CSIC), Campus UAB, Carrer de Can Magrans, s/n, 08193 Barcelona, Spain 17 Observat´orio Nacional, Rua Gal. Jos´eCristino 77, Rio de Janeiro, RJ - 20921-400, Brazil 18 Department of Physics, IIT Hyderabad, Kandi, Telangana 502285, India 19 Santa Cruz Institute for Particle Physics, Santa Cruz, CA 95064, USA 20 Department of Physics, Stanford University, 382 Via Pueblo Mall, Stanford, CA 94305, USA 21 Center for Astrophysics | Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA 22 Department of Astronomy/Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721- 0065, USA 23 Instituci´oCatalana de Recerca i Estudis Avan¸cats, E-08010 Barcelona, Spain 24 Institut de F´ısica d’Altes Energies (IFAE), The Barcelona Institute of Science and Technology, Campus UAB, 08193 Bellaterra (Barcelona) Spain 25 Department of Astrophysical Sciences, Princeton University, Peyton Hall, Princeton, NJ 08544, USA 26 Department of Physics and Astronomy, Pevensey Building, University of Sussex, Brighton, BN1 9QH, UK 27 School of Physics and Astronomy, University of Southampton, Southampton, SO17 1BJ, UK 28 Instituto de F´ısica Gleb Wataghin, Universidade Estadual de Campinas, 13083-859, Campinas, SP, Brazil We present a catalog of 316 trans-Neptunian bodies (TNOs) detected from the first four seasons (“Y4” data) of the Dark Energy Survey (DES). The survey covers a contiguous 5000 deg2 of the southern sky in the grizY optical/NIR filter set, with a typical TNO in this part of the sky being targeted by 25-30 4 Y4 exposures. This paper focusses on the methods used to detect these objects from the ≈60,000 Y4 exposures, a process made challenging by the absence of the few-hour repeat observations employed by TNO-optimized surveys. Newly developed techniques include: transient/moving object detection by comparison of single-epoch catalogs to catalogs of “stacked” images; quantified astrometric error from atmospheric turbulence; new software for detecting TNO linkages in a temporally sparse transient catalog, and for estimating the rate of spurious linkages; and use of faint stars to determine the detection efficiency vs magnitude in all exposures.