The Adoption of Standard Time Author(S): Ian R
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What Time Is It?
The Astronomical League A Federation of Astronomical Societies Astro Note E3 – What Time Is It? Introduction – There are many methods used to keep time, each having its own special use and advantage. Until recently, when atomic clocks became available, time was reckoned by the Earth's motions: one rotation on its axis was a "day" and one revolution about the Sun was a "year." An hour was one twenty-fourth of a day, and so on. It was convenient to use the position of the Sun in the sky to measure the various intervals. Apparent Time This is the time kept by a sundial. It is a direct measure of the Sun's position in the sky relative to the position of the observer. Since it is dependent on the observer's location, it is also a local time. Being measured according to the true solar position, it is subject to all the irregularities of the Earth's motion. The reference time is 12:00 noon when the true Sun is on the observer's meridian. Mean Time Many of the irregularities in the Earth's motion are due to its elliptical orbit. In order to add some consistency to the measure of time, we use the concept of mean time. Mean time uses the position of a fictitious "mean Sun" which moves smoothly and uniformly across the sky and is insensitive to the irregularities of the Earth’s motion. A mean solar day is 24 hours long. The "Equation of Time," tabulated in almanacs and represented on maps by the analemma, provides the correction between mean and apparent time to allow for the eccentricity of the Earth's orbit. -
Illustrating Time's Shadow Supplements
Illustrating Time's Shadow Supplements Supplemental Shadows This book addresses small indoor sundials of wood, glass, and PVC, as well as outside garden dials of glass, clay, tile, and common building materials. Less common dial features such as the inclined decliner and calendar or declination curves, are covered, as well as the astrolabe, other altitude dials and azimuth time keepers. This book uses empirical, geometric, trigonometric, CAD (computer aided design) both 2d and 3d, spreadsheet, procedural programming, tabular methods, and other techniques. Tables are provided. Simon Wheaton-Smith 1 ILLUSTRATING TIME’S SHADOW The Supplements Supplemental Shadows enhances both the book Illustrating Time’s Shadow as well as its associated Appendices by Simon Wheaton-Smith ISBN 978-0-9960026-1-5 Library of Congress Control Number: 2014904840 Simon Wheaton-Smith www.illustratingshadows.com (c) 2004-2018 Simon Wheaton-Smith All rights reserved. June 12, 2018 2 THE ILLUSTRATING SHADOWS COLLECTION Illustrating Shadows provides several books or booklets:- Simple Shadows Build a horizontal dial for your location. Appropriate theory. Cubic Shadows Introducing a cube dial for your location. Appropriate theory. Cutting Shadows Paper cutouts for you to make sundials with. Illustrating Times Shadow the big book Illustrating Times Shadow ~ Some 400 pages covering almost every aspect of dialing. Includes a short appendix. Appendices Illustrating Times Shadow ~ The Appendices ~ Some 180 pages of optional detailed appendix material. Supplement Supplemental Shadows ~ Material in the form of a series of articles, covers more on the kinds of time, declination confusion, other proofs for the vertical decliner, Saxon, scratch, and mass dials, Islamic prayer times (asr), dial furniture, and so on! Programming Shadows A book discussing many programming languages, their systems and how to get them, many being free, and techniques for graphical depictions. -
NIST Time and Frequency Services (NIST Special Publication 432)
Time & Freq Sp Publication A 2/13/02 5:24 PM Page 1 NIST Special Publication 432, 2002 Edition NIST Time and Frequency Services Michael A. Lombardi Time & Freq Sp Publication A 2/13/02 5:24 PM Page 2 Time & Freq Sp Publication A 4/22/03 1:32 PM Page 3 NIST Special Publication 432 (Minor text revisions made in April 2003) NIST Time and Frequency Services Michael A. Lombardi Time and Frequency Division Physics Laboratory (Supersedes NIST Special Publication 432, dated June 1991) January 2002 U.S. DEPARTMENT OF COMMERCE Donald L. Evans, Secretary TECHNOLOGY ADMINISTRATION Phillip J. Bond, Under Secretary for Technology NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY Arden L. Bement, Jr., Director Time & Freq Sp Publication A 2/13/02 5:24 PM Page 4 Certain commercial entities, equipment, or materials may be identified in this document in order to describe an experimental procedure or concept adequately. Such identification is not intended to imply recommendation or endorsement by the National Institute of Standards and Technology, nor is it intended to imply that the entities, materials, or equipment are necessarily the best available for the purpose. NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY SPECIAL PUBLICATION 432 (SUPERSEDES NIST SPECIAL PUBLICATION 432, DATED JUNE 1991) NATL. INST.STAND.TECHNOL. SPEC. PUBL. 432, 76 PAGES (JANUARY 2002) CODEN: NSPUE2 U.S. GOVERNMENT PRINTING OFFICE WASHINGTON: 2002 For sale by the Superintendent of Documents, U.S. Government Printing Office Website: bookstore.gpo.gov Phone: (202) 512-1800 Fax: (202) -
Overview of the National Measurement System's Time and Frequency Programme
Overview of the National Measurement System’s Time and Frequency Programme Dale Henderson Projects to support the maintenance of UTC “The Maintenance and Development of UTC(NPL)” The objectives of this project are to support the operation and development of the international civil time scale, Coordinated Universal Time (UTC), in partnership with the BIPM and the national time standards laboratories from other countries around the world; and to provide a reference time standard for the UK that is traceable to the international civil time scale, Coordinated Universal Time (UTC). Its main deliverable is UTC(NPL), a continuously operating national time scale that is traceable to UTC, with the uncertainty in the UTC-UTC(NPL) offsets published in the BIPM Circular T to be established with an uncertainty of ± 5 ns (1s) or better. UTC and TAI UT-1 is based on siderial time as monitored by the IERS TAI maintained by BIPM under the Metre Convention TAI is an Atomic time, step interval 1 SI second on the Geoid UTC is “owned” by ITU (recommendation TF 460) and has the rate of TAI but is stepped to follow UT-1 International time-keeping since 1972 40 time laboratories around the world with more than 200 atomic clocks keep world time Laboratory time standards compared using satellite links Global standards – International Atomic Time (TAI) and Coordinated Universal Time (UTC) – are computed by the BIPM each calendar month System calibrated by ~8 primary frequency standards 150 100 50 USNO PTB 0 NPL 50800 51300 51800 IEN -50 UTC - UTC(k) [ns] -100 -150 -
Time and Frequency Division Report
Time and Frequency Division Goal The broad mission of the Time and Frequency Division is to provide official U.S. time and related quantities to support a wide range of uses in industry, national infrastructure, research, and among the general public. DIVISION STRATEGY The division’s research and metrology ac- tivities comprise three vertically integrated components, each of which constitutes a strategic element: 1. Official time: Accurate and precise realization of official U.S. time (UTC) and frequency. 2. Dissemination: A wide range of mea- surement services to efficiently and effectively distribute U.S. time and frequency and related quantities – pri- marily through free broadcast services available to any user 24/7/365. 3. Research: Research and technolo- gy development to improve time and frequency standards and dissemination. Part of this research includes high-impact programs in areas such as quantum information processing, atom-based sensors, and laser development and applications, which evolved directly from research to make better frequency standards (atomic clocks). Overview These three components – official time, dissemination, and research – are closely integrated. For example, all Division dissemination services tie directly to the Division’s realization of official time (UTC), and much of the Division’s research is enabled by the continual availability of precision UTC. Our modern technology and economy depend critically on the broad availability of precision timing, frequency, and synchronization. NIST realization and dissemination of time and frequency – continually improved by NIST research and development – is a crucial part of a series of informal national timing infrastructures that enable such essential technologies as: • Telecommunications and computer networks • Utility distribution • GPS, widely available in every cell phone and smartphone as well as GPS receivers • Electronic financial transactions 1 • National security and intelligence applications • Research Strategic Goal: Official Time Intended Outcome and Background U.S. -
Kintaro Hattori in 1881 Founded the Company That Was to Become Seiko
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½PPEZSMHMRXLI)RKPMWLPERKYEKIPMXIVEXYVIEFSYXXLITEWXTVIWIRXERHJYXYVI SJXLIGSQTER]8LIEYXLSV .SLR+SSHEPPMWENSYVREPMWX[LSLEWWTIRXQSWXSJLMW[SVOMRK PMJI[VMXMRKEFSYX[EXGLIWERHXLI[EXGLQEVOIX¯JSVRIEVP]]IEVWEWXLIIHMXSVSJXLI PIEHMRK&VMXMWLXVEHIRI[WTETIV[LMGL[EWXLIRGEPPIH6IXEMP.I[IPPIVERHWYFWIUYIRXP]EW XLIIHMXSVSJE[EXGLQEKE^MRIJSVIRXLYWMEWXW*SVXLIPEWX]IEVWLILEWFIIREJVIIPERGI NSYVREPMWX[VMXMRKEFSYX[EXGLIWJSVLMKLUYEPMX]QEKE^MRIWERHREXMSREPRI[WTETIVW,MW EVXMGPIWLEZIFIIRTYFPMWLIHMRXLI97%-XEP]+IVQER]*VERGIXLI9/ERH.ETER '328)287 'LETXIV ,YQFPI&IKMRRMRKW'VIEXIE7SYRH*SYRHEXMSR 8LIIEVP]7IMOSWXSV] 'LETXIV -RRSZEXMSRERH6IßRIQIRX %RI[HMVIGXMSRJSVXLIWXGIRXYV] 'LETXIV 8LI(IZIPSTQIRX=IEVW 8LIIEVP]LMWXSV]¯ 'LETXIV 'SQTIXMXMSRW7TYVVIH7IMOSXS2I[,IMKLXW -RXIVREXMSREPVIGSKRMXMSR 'LETXIV 8LI4MRREGPISJ1IGLERMGEP)\GIPPIRGI 8LIWXSV]SJXLI+VERH7IMOSGSPPIGXMSR 'LETXIV 8LI(E]XLEX'LERKIHXLI,MWXSV]SJ8MQI 8LIEHZIRXSJUYEVX^XIGLRSPSK] 'LETXIV /MRIXMG;EXGLIW®%PP 8LEXMW&IWXMR7IMOS8IGLRSPSK] 8LIGLEPPIRKISJGPIERIRIVK] 'LETXIV 8LI²+VEQQEVSJ(IWMKR³ -
Representation of Date and Time Data Standard
REPRESENTATION OF DATE AND TIME DATA STANDARD Standard No.: EX000013.1 January 6, 2006 This standard has been produced through the Environmental Data Standards Council (EDSC). Representation of Date and Time Data Standard Std No.: EX000013.1 Foreword The Environmental Data Standards Council (EDSC) identifies, prioritizes and pursues the creation of data standards for those areas where information exchange standards will provide the most value in achieving environmental results. The Council involves Tribes and Tribal Nations, state and federal agencies in the development of the standards and then provides the draft materials for general review. Business groups, non-governmental organizations, and other interested parties may then provide input and comment for Council consideration and standard finalization. Standards are available at http://www.epa.gov/datastandards 1.0 INTRODUCTION This is a format standard which indicates how one displays a particular day within a Gregorian calendar month and specifies an instance of time in the day. Time is expressed in Coordinated Universal Time (UTC). UTC is the official time scale, maintained by the Bureau International des Poids et Mesures (BIPM), and the International Earth Rotation Service (IERS). Examples of the formats follow: a. Date only format When the need is for an expression only of a calendar date, then the complete representation shall be a single numeric data element comprising eight digits, where [YYYY] represents a calendar year, [MM] the ordinal number of a calendar month within the calendar year, and [DD] the ordinal number of a day within the calendar month. Extended format: YYYY-MM-DD EXAMPLE 1985-04-12 b. -
Best Practices for Leap Second Event Occurring on 30 June 2015
26 May 2015 Best Practices for Leap Second Event Occurring on 30 June 2015 Sponsored by the National Cybersecurity and Communications Integration Center in coordination with the United States Naval Observatory, National Institute of Standards and Technology, the USCG Navigation Center, and the National Coordination Office for Space-Based Positioning, Navigation and Timing. This product is intended to assist federal, state, local, and private sector organizations with preparations for the 30-June 2015 Leap Second event. Entities using precision time should be mindful that no leap second adjustment has occurred on a non- holiday weekday in the past decade. Of the three leap seconds implemented since 2000, two have been scheduled on 31 December and the most recent was on Sunday, 1 July 2012. Please report operational challenges you experience to the following organizations: GPS -- United States Coast Guard Navigation Center (NAVCEN), via the NAVCEN Website, http://www.navcen.uscg.gov/ under "Report a GPS Problem" Network Timing Protocols (NTP) -- Michael Lombardi at NIST, Boulder, Colorado at 303-497- 3212, or [email protected]. ============================================= 1. Leap Second Introduction The Coordinated Universal Time (UTC) time standard, based on atomic clocks, is widely used for international timekeeping and as the reference for time in most countries. UTC is the basis of legal time for most of the world. UTC must be adjusted at irregular intervals to maintain its correlation to mean solar time due to irregularities in the Earth’s rotation. These adjustments, called leap seconds, are pre-determined. The next leap second will occur on 30 June 2015 at 23:59:59 UTC. -
Time and Frequency Users' Manual
,>'.)*• r>rJfl HKra mitt* >\ « i If I * I IT I . Ip I * .aference nbs Publi- cations / % ^m \ NBS TECHNICAL NOTE 695 U.S. DEPARTMENT OF COMMERCE/National Bureau of Standards Time and Frequency Users' Manual 100 .U5753 No. 695 1977 NATIONAL BUREAU OF STANDARDS 1 The National Bureau of Standards was established by an act of Congress March 3, 1901. The Bureau's overall goal is to strengthen and advance the Nation's science and technology and facilitate their effective application for public benefit To this end, the Bureau conducts research and provides: (1) a basis for the Nation's physical measurement system, (2) scientific and technological services for industry and government, a technical (3) basis for equity in trade, and (4) technical services to pro- mote public safety. The Bureau consists of the Institute for Basic Standards, the Institute for Materials Research the Institute for Applied Technology, the Institute for Computer Sciences and Technology, the Office for Information Programs, and the Office of Experimental Technology Incentives Program. THE INSTITUTE FOR BASIC STANDARDS provides the central basis within the United States of a complete and consist- ent system of physical measurement; coordinates that system with measurement systems of other nations; and furnishes essen- tial services leading to accurate and uniform physical measurements throughout the Nation's scientific community, industry, and commerce. The Institute consists of the Office of Measurement Services, and the following center and divisions: Applied Mathematics -
Time to Change!
Time to Change! “Railway Time” With the introduction of the railway, travel became faster. With every station keeping its own local mean time, the need for a synchronized time arose. The first railway company to implement a common time for all stations, appropriately named “Railway Time,” was the Great Western Railway in November 1840. By 1847, most railways were using “London Time,” the time set at the Royal Observatory in Greenwich. In 1847, the Railway Clearing House, an industry standards body, recommended that Greenwich Mean Time (GMT) be adopted at all stations as soon as the General Post Office permitted it. On December 1, 1847, the London and North Western Railway, as well as the Caledonian Railway, adopted “London Time,” and by 1848 most railways had followed. Unofficial GMT By 1844, almost all towns and cities in Britain had adopted GMT, though the time standard received some resistance, with railway stations keeping local mean time and showing “London Time” with an additional minute hand on the clock. In 1862, the Great Clock of Westminster, popularly known as Big Ben, was installed. Though not controlled by the Royal Observatory at Greenwich, it received hourly time signals from Greenwich and returned signals twice daily. Standard Time Adopted However, it was not until 1880 that the British legal system caught up with the rest of the country. With the Statutes (Definition of Time) Act (43 & 44 Vict.), Greenwich Mean Time was legally adopted throughout the island of Great Britain on August 2, 1880. Images of original British Railways South Region Clocks at Bat & Ball Station Above – Clock circa 1950 ex Ashford Station Below – Clock circa 1949 ex Dartford Station . -
7XV5664 /7XV5654 GPS/DCF77 Time Synchronization System
13 Relay Communication Equipment / 7XV5664 7XV5664 /7XV5654 GPS/DCF77 Time Synchronization System Features/function overview • GPS exterior antenna with wall mounting and 25 m cable RG59, LSP2410-afp.tif lightning protection is optional • GPS-antenna input (BNC-plug) • PC-input, RS232 (9-pol. Sub-D plug) with operating program and 1m con- nection cable • 2 optical signal outputs FL1/2 for FO cable 62,5/125 µm and ST-plug for disturbance free transmission of the LSP2508.eps signals • Auxiliary voltage 18-60 V DC/option- GPS-time 7XV5654 time ally with wide-range power supply signal receiver synchronization unit 7XV5810-0AA10, 24-250 V DC / (sync.-transceiver) Fig. 13/50 100-230 V AC. GPS/DFC77 • Aluminium housing for rail mounting. time synchronization system Standard Version 7XV5664-0CA00: • Signal outputs FL1/2: telegrams Description selectable IRIG-B, DCF77-, NMEA, IEC60870-5-103, second or minute With the GPS-time signal receiver 7XV5664 and additional components wide-range impulses. power supply 7XV5810, mini star-coupler • 3D-mode with at least 4 satellites or 7XV5450 and sync-transceiver 7XV5654, Fix-mode with at least 1 satellite. a comprehensive solution for time syn- chronization of any number of SIPROTEC Special Version 7XV5664-0AA00: protection devices is possible. A simple • Signal outputs FL1/2: fixed telegrams PC-Software (included in the scope of de- FL 1 = highly accurate second impulse livery) facilitates the setting of the receiver via a RS232 interface. The transmission FL 2 = IRIG-B or DCF77 of the time signals (telegrams or impulses) • Only 3D-mode with at least 4 satellites. -
Railway Reminiscences
rafc ^' NQTJSS ''SUPEB/. CORNELL UNIVERSITY LIBRARY FROM Cornell University Library HE3018.2.N37 A3 Railway reminiscences. 3 1924 030 116 960 olin RAILWAY REMINISCENCES. All books are subject to recall after two weeks Olin/Kroch Library DATE DUE ' RAILWAY REMINISCENCES BY GEORGE P. NEELE, LATE SUTERINTENDENT OF THE LINE OF THE LONDON AND NORTH WESTERN RAILWAY. NOTES AND REMINISCENCES OF HALF A century's PROGRESS IN RAILWAY WORKING, AND OF A RAILWAY SUPERINTENDENT'S LIFE, PRINCIPALLY ON THE LONDON AND NORTH WESTERN RAILWAY, WITH SOME SUPPLEMENTARY MEMORANDA AS TO THE RAILWAY JOURNEYS TO AND FROM SCOTLAND MADE BY HER LATE MAJESTY QUEEN VICTORIA. XonDon: M'^CORQUODALE & CO., LIMITED, PRINTERS, CARDINGTON STREET. 1904. ^7 A77373S" PREFACE. Owing to suggestions made from time to time by old comrades in railway life, I have been induced to put together some record of the part I have taken in connection with the inner working of Railways; going back to very early experiences, and through gradual developments extending over a long series of years, to the time when it became advisable for me to retire from the daily pressure of the work. A railway service commencing in 1847, carries one back a long way towards association with those who were the actual pioneers of our railway system ; from whom we learnt our first lessons, by whose successes we have profited, by whose failures we have acquired knowledge ; and on whose foundation we have endeavoured to raise a superstructure of so sub- stantial a character, that those who follow in our steps will have no reason to be ashamed of their predecessors.