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Ephemeris Time, D. H. Sadler, Occasional
EPHEMERIS TIME D. H. Sadler 1. Introduction. – At the eighth General Assembly of the International Astronomical Union, held in Rome in 1952 September, the following resolution was adopted: “It is recommended that, in all cases where the mean solar second is unsatisfactory as a unit of time by reason of its variability, the unit adopted should be the sidereal year at 1900.0; that the time reckoned in these units be designated “Ephemeris Time”; that the change of mean solar time to ephemeris time be accomplished by the following correction: ΔT = +24°.349 + 72s.318T + 29s.950T2 +1.82144 · B where T is reckoned in Julian centuries from 1900 January 0 Greenwich Mean Noon and B has the meaning given by Spencer Jones in Monthly Notices R.A.S., Vol. 99, 541, 1939; and that the above formula define also the second. No change is contemplated or recommended in the measure of Universal Time, nor in its definition.” The ultimate purpose of this article is to explain, in simple terms, the effect that the adoption of this resolution will have on spherical and dynamical astronomy and, in particular, on the ephemerides in the Nautical Almanac. It should be noted that, in accordance with another I.A.U. resolution, Ephemeris Time (E.T.) will not be introduced into the national ephemerides until 1960. Universal Time (U.T.), previously termed Greenwich Mean Time (G.M.T.), depends both on the rotation of the Earth on its axis and on the revolution of the Earth in its orbit round the Sun. There is now no doubt as to the variability, both short-term and long-term, of the rate of rotation of the Earth; U.T. -
CO Multi-Line Imaging of Nearby Galaxies (COMING) IV. Overview Of
Publ. Astron. Soc. Japan (2018) 00(0), 1–33 1 doi: 10.1093/pasj/xxx000 CO Multi-line Imaging of Nearby Galaxies (COMING) IV. Overview of the Project Kazuo SORAI1, 2, 3, 4, 5, Nario KUNO4, 5, Kazuyuki MURAOKA6, Yusuke MIYAMOTO7, 8, Hiroyuki KANEKO7, Hiroyuki NAKANISHI9 , Naomasa NAKAI4, 5, 10, Kazuki YANAGITANI6 , Takahiro TANAKA4, Yuya SATO4, Dragan SALAK10, Michiko UMEI2 , Kana MOROKUMA-MATSUI7, 8, 11, 12, Naoko MATSUMOTO13, 14, Saeko UENO9, Hsi-An PAN15, Yuto NOMA10, Tsutomu, T. TAKEUCHI16 , Moe YODA16, Mayu KURODA6, Atsushi YASUDA4 , Yoshiyuki YAJIMA2 , Nagisa OI17, Shugo SHIBATA2, Masumichi SETA10, Yoshimasa WATANABE4, 5, 18, Shoichiro KITA4, Ryusei KOMATSUZAKI4 , Ayumi KAJIKAWA2, 3, Yu YASHIMA2, 3, Suchetha COORAY16 , Hiroyuki BAJI6 , Yoko SEGAWA2 , Takami TASHIRO2 , Miho TAKEDA6, Nozomi KISHIDA2 , Takuya HATAKEYAMA4 , Yuto TOMIYASU4 and Chey SAITA9 1Department of Physics, Faculty of Science, Hokkaido University, Kita 10 Nishi 8, Kita-ku, Sapporo 060-0810, Japan 2Department of Cosmosciences, Graduate School of Science, Hokkaido University, Kita 10 Nishi 8, Kita-ku, Sapporo 060-0810, Japan 3Department of Physics, School of Science, Hokkaido University, Kita 10 Nishi 8, Kita-ku, Sapporo 060-0810, Japan 4Division of Physics, Faculty of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8571, Japan 5Tomonaga Center for the History of the Universe (TCHoU), University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8571, Japan 6Department of Physical Science, Osaka Prefecture University, Gakuen 1-1, -
Calculation of Moon Phases and 24 Solar Terms
Calculation of Moon Phases and 24 Solar Terms Yuk Tung Liu (廖²棟) First draft: 2018-10-24, Last major revision: 2021-06-12 Chinese Versions: ³³³qqq---文文文 简简简SSS---文文文 This document explains the method used to compute the times of the moon phases and 24 solar terms. These times are important in the calculation of the Chinese calendar. See this page for an introduction to the 24 solar terms, and this page for an introduction to the Chinese calendar calculation. Computation of accurate times of moon phases and 24 solar terms is complicated, but today all the necessary resources are freely available. Anyone familiar with numerical computation and computer programming can follow the procedure outlined in this document to do the computation. Before stating the procedure, it is useful to have a basic understanding of the basic concepts behind the computation. I assume that readers are already familiar with the important astronomy concepts mentioned on this page. In Section 1, I briefly introduce the barycentric dynamical time (TDB) used in modern ephemerides, and its connection to terrestrial time (TT) and international atomic time (TAI). Readers who are not familiar with general relativity do not have to pay much attention to the formulas there. Section 2 introduces the various coordinate systems used in modern astronomy. Section 3 lists the formulas for computing the IAU 2006/2000A precession and nutation matrices. One important component in the computation of accurate times of moon phases and 24 solar terms is an accurate ephemeris of the Sun and Moon. I use the ephemerides developed by the Jet Propulsion Laboratory (JPL) for the computation. -
June 2013 BRAS Newsletter
www.brastro.org June 2013 What's in this issue: PRESIDENT'S MESSAGE .............................................................................................................................. 2 NOTES FROM THE VICE PRESIDENT ........................................................................................................... 3 MESSAGE FROM THE HRPO ...................................................................................................................... 4 OBSERVING NOTES ..................................................................................................................................... 6 MAY ASTRONOMICAL EVENTS .................................................................................................................... 9 PRESIDENT'S MESSAGE Greetings Everyone, Summer is here and with it the humidity and bugs, but I hope that won't stop you from getting out to see some of the great summer time objects in the sky. Also, Saturn is looking quite striking as the rings are now tilted at a nice angle allowing us to see the Casini Division and shadows on and from the planet. Don't miss it! I've been asked by BREC to make sure our club members are all aware of the Park Rules listed on BREC's website. Many of the rules are actually ordinances enacted by the city of Baton Rouge (e.g., No smoking permitted in public areas, No alcohol brought onto or sold on BREC property, No Gambling, No Firearms or Weapons, etc.) Please make sure you observe all of the Park Rules while at the HRPO and provide good examples for the general public. (Many of which are from outside East Baton Rouge Parish and are likely unaware of some of the policies.) For a full list of BREC's Park Rules, you may visit their Park Rules section of their website at http://brec.org/index.cfm/page/555/n/75 I'm sorry I had to miss the outing to LIGO, but it will be good to see some folks again at our meeting on Monday, June 10th. -
The Calendars of India
The Calendars of India By Vinod K. Mishra, Ph.D. 1 Preface. 4 1. Introduction 5 2. Basic Astronomy behind the Calendars 8 2.1 Different Kinds of Days 8 2.2 Different Kinds of Months 9 2.2.1 Synodic Month 9 2.2.2 Sidereal Month 11 2.2.3 Anomalistic Month 12 2.2.4 Draconic Month 13 2.2.5 Tropical Month 15 2.2.6 Other Lunar Periodicities 15 2.3 Different Kinds of Years 16 2.3.1 Lunar Year 17 2.3.2 Tropical Year 18 2.3.3 Siderial Year 19 2.3.4 Anomalistic Year 19 2.4 Precession of Equinoxes 19 2.5 Nutation 21 2.6 Planetary Motions 22 3. Types of Calendars 22 3.1 Lunar Calendar: Structure 23 3.2 Lunar Calendar: Example 24 3.3 Solar Calendar: Structure 26 3.4 Solar Calendar: Examples 27 3.4.1 Julian Calendar 27 3.4.2 Gregorian Calendar 28 3.4.3 Pre-Islamic Egyptian Calendar 30 3.4.4 Iranian Calendar 31 3.5 Lunisolar calendars: Structure 32 3.5.1 Method of Cycles 32 3.5.2 Improvements over Metonic Cycle 34 3.5.3 A Mathematical Model for Intercalation 34 3.5.3 Intercalation in India 35 3.6 Lunisolar Calendars: Examples 36 3.6.1 Chinese Lunisolar Year 36 3.6.2 Pre-Christian Greek Lunisolar Year 37 3.6.3 Jewish Lunisolar Year 38 3.7 Non-Astronomical Calendars 38 4. Indian Calendars 42 4.1 Traditional (Siderial Solar) 42 4.2 National Reformed (Tropical Solar) 49 4.3 The Nānakshāhī Calendar (Tropical Solar) 51 4.5 Traditional Lunisolar Year 52 4.5 Traditional Lunisolar Year (vaisnava) 58 5. -
Astronomical Time Keeping file:///Media/TOSHIBA/Times.Htm
Astronomical Time Keeping file:///media/TOSHIBA/times.htm Astronomical Time Keeping Introduction Siderial Time Solar Time Universal Time (UT), Greenwich Time Timezones Atomic Time Ephemeris Time, Dynamical Time Scales (TDT, TDB) Julian Day Numbers Astronomical Calendars References Introduction: Time keeping and construction of calendars are among the oldest branches of astronomy. Up until very recently, no earth-bound method of time keeping could match the accuracy of time determinations derived from observations of the sun and the planets. All the time units that appear natural to man are caused by astronomical phenomena: The year by Earth's orbit around the Sun and the resulting run of the seasons, the month by the Moon's movement around the Earth and the change of the Moon phases, the day by Earth's rotation and the succession of brightness and darkness. If high precision is required, however, the definition of time units appears to be problematic. Firstly, ambiguities arise for instance in the exact definition of a rotation or revolution. Secondly, some of the basic astronomical processes turn out to be uneven and irregular. A problem known for thousands of years is the non-commensurability of year, month, and day. Neither can the year be precisely expressed as an integer number of months or days, nor does a month contain an integer number of days. To solves these problems, a multitude of time scales and calenders were devised of which the most important will be described below. Siderial Time The siderial time is deduced from the revolution of the Earth with respect to the distant stars and can therefore be determined from nightly observations of the starry sky. -
Swiss Ephemeris: an Accurate Ephemeris Toolset for Astronomy and Astrology
NOTICES Swiss Ephemeris: An Accurate Ephemeris Toolset for Astronomy and Astrology Victor Reijs Independent scholar [email protected] Ralf Stubner Independent scholar [email protected] Introduction The Swiss Ephemeris is a highly accurate ephemeris toolset developed since 1997 by Astrodienst (Koch and Triendl 2004). It is based upon the DE430/DE431 ephemerides from NASA’s JPL (Folkner et al. 2014) and covers the time range 13,000 BC to AD 17,000. For both astronomical and astrological coordinates (true equinox of date), all corrections such as relativistic aberration, deflection of light in the gravity field of the Sun and others have been included. The Swiss Ephemeris is not a product that can be easily used by end users, but it is an accurate and fast toolset for programmers to build into their own astronomical or astrological software. A few examples where this toolset is used include the swephR package for the R environment (Stubner and Reijs 2019) and ARCHAEOCOSMO, which is used within both Excel and R (Reijs 2006). All discussed packages have open source versions. To provide flexibility (mainly in processing and memory needs), Swiss Ephemeris can use three ephemerides, giving the user the choice of which to use. First there are the original JPL ephemerides data files. These data files need a lot of memory (around 3 GB) and provide the most accurate ephemeris at this moment. The second (and default) SE ephemeris uses Astrodienst’s data files. Astrodienst used sophisticated compres- sion techniques to reduce the original DE430/DE431 data files to around 100 MB. -
Lopsided Spiral Galaxies: Evidence for Gas Accretion
A&A 438, 507–520 (2005) Astronomy DOI: 10.1051/0004-6361:20052631 & c ESO 2005 Astrophysics Lopsided spiral galaxies: evidence for gas accretion F. Bournaud1, F. Combes1,C.J.Jog2, and I. Puerari3 1 Observatoire de Paris, LERMA, 61 Av. de l’Observatoire, 75014 Paris, France e-mail: [email protected] 2 Department of Physics, Indian Institute of Science, Bangalore 560012, India 3 Instituto Nacional de Astrofísica, Optica y Electrónica, Calle Luis Enrique Erro 1, 72840 Tonantzintla, Puebla, Mexico Received 3 January 2005 / Accepted 15 March 2005 Abstract. We quantify the degree of lopsidedness for a sample of 149 galaxies observed in the near-infrared from the OSUBGS sample, and try to explain the physical origin of the observed disk lopsidedness. We confirm previous studies, but for a larger sample, that a large fraction of galaxies have significant lopsidedness in their stellar disks, measured as the Fourier amplitude of the m = 1 component normalised to the average or m = 0 component in the surface density. Late-type galaxies are found to be more lopsided, while the presence of m = 2 spiral arms and bars is correlated with disk lopsidedness. We also show that the m = 1 amplitude is uncorrelated with the presence of companions. Numerical simulations were carried out to study the generation of m = 1viadifferent processes: galaxy tidal encounters, galaxy mergers, and external gas accretion with subsequent star formation. These simulations show that galaxy interactions and mergers can trigger strong lopsidedness, but do not explain several independent statistical properties of observed galaxies. To explain all the observational results, it is required that a large fraction of lopsidedness results from cosmological accretion of gas on galactic disks, which can create strongly lopsided disks when this accretion is asymmetrical enough. -
Atlas Menor Was Objects to Slowly Change Over Time
C h a r t Atlas Charts s O b by j Objects e c t Constellation s Objects by Number 64 Objects by Type 71 Objects by Name 76 Messier Objects 78 Caldwell Objects 81 Orion & Stars by Name 84 Lepus, circa , Brightest Stars 86 1720 , Closest Stars 87 Mythology 88 Bimonthly Sky Charts 92 Meteor Showers 105 Sun, Moon and Planets 106 Observing Considerations 113 Expanded Glossary 115 Th e 88 Constellations, plus 126 Chart Reference BACK PAGE Introduction he night sky was charted by western civilization a few thou - N 1,370 deep sky objects and 360 double stars (two stars—one sands years ago to bring order to the random splatter of stars, often orbits the other) plotted with observing information for T and in the hopes, as a piece of the puzzle, to help “understand” every object. the forces of nature. The stars and their constellations were imbued with N Inclusion of many “famous” celestial objects, even though the beliefs of those times, which have become mythology. they are beyond the reach of a 6 to 8-inch diameter telescope. The oldest known celestial atlas is in the book, Almagest , by N Expanded glossary to define and/or explain terms and Claudius Ptolemy, a Greco-Egyptian with Roman citizenship who lived concepts. in Alexandria from 90 to 160 AD. The Almagest is the earliest surviving astronomical treatise—a 600-page tome. The star charts are in tabular N Black stars on a white background, a preferred format for star form, by constellation, and the locations of the stars are described by charts. -
Starshade Rendezvous Probe
Starshade Rendezvous Probe Starshade Rendezvous Probe Study Report Imaging and Spectra of Exoplanets Orbiting our Nearest Sunlike Star Neighbors with a Starshade in the 2020s February 2019 TEAM MEMBERS Principal Investigators Sara Seager, Massachusetts Institute of Technology N. Jeremy Kasdin, Princeton University Co-Investigators Jeff Booth, NASA Jet Propulsion Laboratory Matt Greenhouse, NASA Goddard Space Flight Center Doug Lisman, NASA Jet Propulsion Laboratory Bruce Macintosh, Stanford University Stuart Shaklan, NASA Jet Propulsion Laboratory Melissa Vess, NASA Goddard Space Flight Center Steve Warwick, Northrop Grumman Corporation David Webb, NASA Jet Propulsion Laboratory Study Team Andrew Romero-Wolf, NASA Jet Propulsion Laboratory John Ziemer, NASA Jet Propulsion Laboratory Andrew Gray, NASA Jet Propulsion Laboratory Michael Hughes, NASA Jet Propulsion Laboratory Greg Agnes, NASA Jet Propulsion Laboratory Jon Arenberg, Northrop Grumman Corporation Samuel (Case) Bradford, NASA Jet Propulsion Laboratory Michael Fong, NASA Jet Propulsion Laboratory Jennifer Gregory, NASA Jet Propulsion Laboratory Steve Matousek, NASA Jet Propulsion Laboratory Jonathan Murphy, NASA Jet Propulsion Laboratory Jason Rhodes, NASA Jet Propulsion Laboratory Dan Scharf, NASA Jet Propulsion Laboratory Phil Willems, NASA Jet Propulsion Laboratory Science Team Simone D'Amico, Stanford University John Debes, Space Telescope Science Institute Shawn Domagal-Goldman, NASA Goddard Space Flight Center Sergi Hildebrandt, NASA Jet Propulsion Laboratory Renyu Hu, NASA -
FY13 High-Level Deliverables
National Optical Astronomy Observatory Fiscal Year Annual Report for FY 2013 (1 October 2012 – 30 September 2013) Submitted to the National Science Foundation Pursuant to Cooperative Support Agreement No. AST-0950945 13 December 2013 Revised 18 September 2014 Contents NOAO MISSION PROFILE .................................................................................................... 1 1 EXECUTIVE SUMMARY ................................................................................................ 2 2 NOAO ACCOMPLISHMENTS ....................................................................................... 4 2.1 Achievements ..................................................................................................... 4 2.2 Status of Vision and Goals ................................................................................. 5 2.2.1 Status of FY13 High-Level Deliverables ............................................ 5 2.2.2 FY13 Planned vs. Actual Spending and Revenues .............................. 8 2.3 Challenges and Their Impacts ............................................................................ 9 3 SCIENTIFIC ACTIVITIES AND FINDINGS .............................................................. 11 3.1 Cerro Tololo Inter-American Observatory ....................................................... 11 3.2 Kitt Peak National Observatory ....................................................................... 14 3.3 Gemini Observatory ........................................................................................ -
7.5 X 11.5.Threelines.P65
Cambridge University Press 978-0-521-19267-5 - Observing and Cataloguing Nebulae and Star Clusters: From Herschel to Dreyer’s New General Catalogue Wolfgang Steinicke Index More information Name index The dates of birth and death, if available, for all 545 people (astronomers, telescope makers etc.) listed here are given. The data are mainly taken from the standard work Biographischer Index der Astronomie (Dick, Brüggenthies 2005). Some information has been added by the author (this especially concerns living twentieth-century astronomers). Members of the families of Dreyer, Lord Rosse and other astronomers (as mentioned in the text) are not listed. For obituaries see the references; compare also the compilations presented by Newcomb–Engelmann (Kempf 1911), Mädler (1873), Bode (1813) and Rudolf Wolf (1890). Markings: bold = portrait; underline = short biography. Abbe, Cleveland (1838–1916), 222–23, As-Sufi, Abd-al-Rahman (903–986), 164, 183, 229, 256, 271, 295, 338–42, 466 15–16, 167, 441–42, 446, 449–50, 455, 344, 346, 348, 360, 364, 367, 369, 393, Abell, George Ogden (1927–1983), 47, 475, 516 395, 395, 396–404, 406, 410, 415, 248 Austin, Edward P. (1843–1906), 6, 82, 423–24, 436, 441, 446, 448, 450, 455, Abbott, Francis Preserved (1799–1883), 335, 337, 446, 450 458–59, 461–63, 470, 477, 481, 483, 517–19 Auwers, Georg Friedrich Julius Arthur v. 505–11, 513–14, 517, 520, 526, 533, Abney, William (1843–1920), 360 (1838–1915), 7, 10, 12, 14–15, 26–27, 540–42, 548–61 Adams, John Couch (1819–1892), 122, 47, 50–51, 61, 65, 68–69, 88, 92–93,