Nautical Almanac Research Articles

The NAV-AID: A Calculator for Navigation

A description is given of a proposed versatile navigator's aid (NAV-AID) made possible by recent advances in calculator technology. The NAV-AID is a portable microdigital computer which, when used with The Nautical Almanac, solves Celestial, Loran and Omega position fixing problems. Additionally, the NAV-AID contains a Deduced Reckoning computer as well as the capability to perform a variety of standard piloting techniques. Subroutines enable the navigator to calculate useful course line parameters and to handle sextant altitude and Omega skywave corrections. Other course and fix-related quantities are accessible through an Auxiliary Data Mode. An Inverse Mode allows Celestial, Loran and Omega data to be predicted, and a Calculator Mode aids in external computations. Anticipated specifications are given.

Sight Reduction Using the Portable Sextant Computer System

Sight reduction procedures in marine navigation have been traditional for nearly a century and a half, just as the marine sextant, itself, has been essentially the same design for 250 years. The reduction of each sextant sight to true azimuth and altitude intercept requires the use of standard forms, The Nautical Almanac, and several volumes of sight reduction tables. The procedure is tedious and time consuming, and errors in data selection and arithmetic are common. A low-cost, specialized, small portable computer that operates with the sextant can be developed to relieve the navigator of his calculation tedium and blunders and improve his navigation accuracy. The design of such a small computer is feasible today. The logic and a functional computer program have been developed that combines the necessary data and spherical trigonometric equations to reduce the altitude measurements of the stars to data ready for plotting by the navigator. This paper will discuss the new digital readout day/night marine sextant which is part of the concept of the portable sextant-computer system, the development of the program for the computer, and its application to solve navigation problems. Furthermore, use of the portable computer will be shown to be applicable to all fields of navigation, although the current development centers around marine navigation.

Gaussian Logarithms and Navigation

The following comments on Captain C. H. Cotter's note (this Journal, Vol. 24, page 569) on the use of addition and subtraction logarithms in navigation may be of interest. Captain C. Carić was not the first to introduce gaussian logarithms to navigators, since their use was advocated, at least to Portuguese navigators, in 1920 by Admiral Gago Coutinho (see my review of Precision Astrolabe by Francis M. Rogers, 25, 135), and actually used by him on his pioneering transatlantic flight in 1922. They are included in several collections of nautical tables, including Tábuas Náuticas by Fontoura and Coutinho, as well as those of Friocourt and Hoüel; but I have been unable to obtain the dates of their first inclusion. However, it is most unlikely that either Coutinho or Carić, who incidentally used quite different basic formulae, were the first to advocate the use of addition and subtraction logarithms, or possibly to publish methods and tables. They were in use to a small extent in astronomical calculations, and to a somewhat larger extent in surveying. Dr. L. J. Comrie, the computer and table-maker, who was Superintendent of H.M. Nautical Almanac Office (N.A.O.) from 1930 to 1936, was an enthusiastic advocate and designed many computational forms incorporating their use.

Plans for the Naval Observatory of Buenos Aires

The Naval Observatory of Buenos Aires was founded In 1860 as a marine observatory to satisfy the needs of nautical and geodetic astronomy in the aid of marine navigation and hydrography. It has provided the official – national time for 50 years.The Observatory carries out computations for the Argentine Nautical Almanac and provides an abridged ephemeris for hydrographic and – topographic work. Since 1955 it has provided standard frequency and time on – the frequencies 5, 10, and 15 MHz through Its transmitting station LOL. During the last two years specific plans were developed for modernizing and – improving the precision of this service. Some of these plans have already been carried out.

Ground Heat Flux Into Several Surfaces During A Partial Solar Eclipse

Ground Heat Flux Into Several Surfaces During A Partial SolarEclipse Gregory E. Borgel* Aspects of the energy balance of the surface during a solar eclipse have been treated on a number of occasions.1 However, none of this work has been particularly concerned with the heat flux into the surfaces common in our urban environment. For this paper the ground heat fluxes (G) into three such surfaces—concrete (Gc), grass (Gg), and tarpaper roofing material (Gr)—were examined. Sample blocks of each of the three surfaces were prepared witii heat flux plates permanentìy imbedded at a depth of .5 cm. Readout was onto Rustrak strip-chart recorders and a Thornthwaite soil heat flux recorder. For purposes of correlation with G measurements, the incoming direct and diffuse solar radiation (global radiation or O + q) were recorded by a star pyranometer read into a strip-chart recorder. * Mr. Rorgel was a graduate student in geography at the University of California, Los Angeles 90024, when this paper was presented at the 1970 meeting of the Association at Santa Cruz. He is currently on leave from UCLA. He expressed thanks to the U. S. Naval Observatory, Washington, D. C, for data on the local solar eclipse, to Stella Louie for computer programming, and to Dr. W. H. Terjung for guidance and assistance. 1 W. N. Abbott, "On certain radiometric effects during the partial solar eclipse of February 25, 1952," Geofis, Pura e Applicada, Vol. 39, (1958), pp. 186-193; P. Jagannathan, O. Chacko, and S. P. Venkiteshwaran, "Insolation measurements at Poona during the solar eclipse on 14 December 1955," Indian Journal of Meteorology and Geophysics, Vol. 8, (1957), pp. 93-98; W. O. Pruitt, F. Lourence, and Todd V. Crawford, "Radiation and energy balance changes during the eclipse of 20 July 1963," Journal of Applied Meteorology, vol. 4 (1965), pp. 272-278; U. Ushiyama, F. Narita, Y. Suzuki, and T. Suzuki, "The variation of the surface meteorological elements," Geophysical Magazine, Vol.19, (1949), pp. 78-94. 171 172ASSOCIATION OF PACIFIC COAST GEOGRAPHERS The eclipse considered in this study occurred on March 7, 1970. At the observation site in the San Fernando Valley, California, the eclipse began at 8:29 a.m., achieved a maximum of 23.7% obscuration of the solar disk at 9:25 a.m., and ended at 10:25 a.m., Pacific Standard Time.2 Solar Radiation Measurements Observed Q + q during the eclipse and "expected" Q -+- q are shown in Figure 1. The latter was derived from data of another study one year earlier at a nearby site.3 A downward adjustment of the "expected" curve was made by varying the transmissivity coefficient by computer until a fit was obtained between the "expected" curve and the observed O + q on the eclipse day before and after the eclipse itself. The observed O + q plotted in Figure 1 was below the "expected " 0 + 9 throughout the eclipse. The maximum percent difference between expected and observed occurred at 9:25, which was also the time of the maximum percent obscuration of the sun. The maximum absolute difference between expected and observed Q + q occurred slightìy after the eclipse maximum because both curves were attaining higher absolute values as solar altitude increased. Table 1. Expected and Observed Q + q in Langleys per Minute "Expected" Observed TimeQ + q Q -{- q DifferenceEclipse PercentPercent 9:00 .........................325 .270 17.016.1 9:20 .........................400 .305 23.823.3 9:25 .........................410 .310 24.123.7 9:40 .........................455 .355 21.921.2 10:00 .........................505 .450 10.911.5 2 Private communication, U.S. Naval Observatory, Nautical Almanac Office, Washington, D.C, 20390. 3 Werner H. Terjung, G. E. Borgel, et al., "The effect of a cyclonic storm on the energy fluxes at the urban interface—a preliminary experiment," Archiv für Meteorologie, Geophysik und Bioklimatologie, Series B, Vol. 19, (1971), in press. YEARBOOK · VOLUME 34 · 1972 173 •5r¦4r¦2r -i--------1---------1---------T- -i------1------r Q+q *~*Exptcttd +"+Ob»»rv«d _l____I____I____1_ _1____I____' ¦____I____I____l_ Figure 1. Expected and observed direct and diffuse solar radiation . 9 IOIl1213» PST Max. Eclipse -i-------?-------1-------1-------1-------?-------1-------t- •4r I -3 Figure 2. "Normal...

Agents for Nautical Publications

Over the past several years. and due in large measure to my association with fellow members of the Society for the History of Discoveries, I have come to realize that modern scholars concerned with the early development of astronomical navigation, surveying, cartography, naval architecture, and naval ordnance are well advised to begin with today's knowledge and practices and work backward in time. With this precept in mind, and limiting myself in general to astronomical navigation, I have taken advantage of trips abroad during the summers of 1967, 1968, 1969, and 1970 to seek out at least one principal and well-stocked nautical store in at least one port city of each of a dozen countries. These countries fall within the cultural zone of Western Europe and employ languages in which I have at least a modicum of competence. (Which is an indirect way of admitting that I do not know Chinese, Japanese, or Russian.) The stores themselves are either official government agencies or official depositories of government nautical publications including charts, in other words, the very nautical (and occasionally air) almanacs, volumes of sight reduction and other navigational tables,1 standard manuals of navigation, and charts and plotting sheets which the scholar needs to have at hand in order to understand the end-product of the evolution which interests him. These stores also normally offer for sale the standard chronometers, sextants, and plotting tools employed by the respective merchant marines. I have found that the managers and employees of these houses constitute a grand international fellowship, and invariably they know the English language. They are hospitable, patient, helpful, and interested in scholarly research. With the thought that they may be of service to readers of Terrae In cognitae, I pass along the names and addresses of the firms or agencies with which they are associated.

International Cooperation

NAVIGATIONVolume 18, Issue 1 p. 110-115 International Cooperation R. L. DUNCOMBE, R. L. DUNCOMBE Dr. Duncombe is Director of the Nautical Almanac Office, U. S. Naval Observatory, Washington, D.C. 20390. He was invited to contribute this paper for the Twenty-Fifth Anniversary Issue of NAVIGATION.Search for more papers by this author R. L. DUNCOMBE, R. L. DUNCOMBE Dr. Duncombe is Director of the Nautical Almanac Office, U. S. Naval Observatory, Washington, D.C. 20390. He was invited to contribute this paper for the Twenty-Fifth Anniversary Issue of NAVIGATION.Search for more papers by this author First published: Spring 1971 https://doi.org/10.1002/j.2161-4296.1971.tb00078.xCitations: 1 AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume18, Issue1Spring 1971Pages 110-115 RelatedInformation

The improvement of the lunar ephemeris

At present the fundamental lunar ephemeris is based on Brown's theory of the motion of the Moon with improvements based on the bypassing of Brown's Tables, the removal of the great empirical term, the substitution of the relevant constants of the IAU system of astronomical constants and the retransformation of Brown's series in rectangular coordinates to spherical coordinates. Even so this ephemeris does not represent adequately the recent range and range-rate radio observations, and it will be inadequate for use in the analysis of laser observations of corner reflectors on the Moon. Numerical integrations for these purposes have already been made at the Jet Propulsion Laboratory, but improved theoretical developments are also required; new solutions of the main problem are in hand elsewhere. Work at H.M. Nautical Almanac Office is aimed at obtaining improved values of the constants of the lunar orbit by a rediscussion of occultation observations made since 1943 and at the redevelopment of the series for the planetary perturbations using more precise theories of the motion of the Sun and planets. The techniques and preliminary results of exploratory numerical integrations were briefly described.

Appendix: Reports of the Directors of the National Ephemerides

During the period under review two issues of the Astronomical Yearbook of the U.S.S.R. for the years 1971, 1972 have been published, and that for 1973 is in preparation. The positions and proper motions of the stars are in the FK4 system as recommended by Commission 4 in 1961. Further, as recommended at the meeting in Hamburg in 1964 (Trans. IAU, 12 B (1964), 105,1966) the IAU System of Astronomical Constants has been introduced into the tabulations of the day numbers, solar and lunar eclipses, ephemerides for physical observations of planets, and the factors S &C. The corresponding differential corrections to the Moon’s ephemeris as well as re-calculated eclipse data for 1971 have been tabulated separately in the Appendix to the Yearbook for 1971. As from the edition of the Yearbook for 1972, the lunar ephemeris j = 2 will be published in accordance with the recommendations adopted in Prague in 1967.The regular publication of the ephemeris of the lunar crater Mösting A has been continued in the editions of the Yearbook mentioned above.Fundamental ephemerides of the Sun, Moon, and planets have been printed in full conformity with the first part of the Astronomical Ephemeris circulated in advance by H. M. Nautical Almanac Office, Royal Greenwich Observatory.

Man Is Not Lost. A record of two hundred years of astronomical navigation with the Nautical Almanac 1767-1967. Pp. 43. 8s. 6d. 1968. (H.M. Stationery Office).

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Spring-restrained, momentum-wheel orientation and stabilization system for exoatmospheric vehicles.

4 Wagner, C. A., Drift of a 24-Hour Satellite due to an Earth Gravity Field through Fourth Order, TN D-2103, Feb. 1964, NASA. 5 Wagner, C. A., Drift of an Inclined-Orbit 24-Hour Satellite in an Earth Gravity Field through Fourth Order, TN D-3316, May 1966, NASA. 6 Sherman, H. et al., Experimental Satellite Program (LES-1, -2, -3, -4), Journal of Spacecraft and Rockets, Vol. 4, No. 11, Nov. 1967, pp. 1448-1452. 7 Braga-Illa, A., Orbit Determination from the Satellite, Journal of Spacecraft and Rockets, Vol. 6, No. 3, March 1969, pp. 232-238. 8 The American Ephemeris and Nautical Almanac for the Year 1969, U.S. Government Printing Office, 1967. 9 Moriarty, B. M., Position Error in Station-Keeping Satellite, TN 1966-21, April 1966, Massachusetts Institute of Technology, Lincoln Laboratory, Lexington, Mass.

Determination of Ephemeris Time and Radius of the Lunar Umbra during the Total Solar Eclipse of 12 November

view Abstract Citations References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Determination of Ephemeris Time and Radius of the Lunar Umbra during the Total Solar Eclipse of 12 November Iannini, Gualberto M. Abstract During the eclipse of 12 November 1966, the second and third contacts and the mideclipse instant were measured. Comparing the results with the Besselian elements published in the American Ephemeris and Nautical Almanac we found TE-TU= 35.73+0.10 and that the radius of the umbra at the observing site must be increased. Publication: The Astronomical Journal Pub Date: October 1968 DOI: 10.1086/110690 Bibcode: 1968AJ.....73..743I full text sources ADS |

‘The Metrication of Navigation’

In his note (Journal 21, 81) on this subject, Ronald Turner says ‘No longer will orbital periods of the rotation of the Earth on its axis be measures of time’. This is not so, either in general or in the particular, case of navigation.Universal Time (U.T.), which is the generally accepted name for Greenwich Mean Time (G.M.T.), continues to be essential for all purposes (in astronomy, geodesy, surveying and navigation) for which are required astronomical observations related to the precise position of the observer on the Earth's surface. The Nautical Almanac must continue to tabulate the positions of the Sun, Moon, planets and stars with G.M.T. as the time-argument; and observations should be timed in a time-system related to U.T., such as the broadcast time-signals of Coordinated Universal Time (U.T.C:).

‘Longitude Without Time’

The Executive Secretary has referred to me two notes on this subject, one by M. S. Dixon and the other by Bruno Ortlepp. Although submitted independently, and at different times, they clearly relate not only to the. same technique, but also to the same set of observations.Now much has been recently written on the determination of time, and thus of longitude, from observations of the Moon's altitude (for example, in this Journal, reference can be made to the notes by Francis Chichester, 19, 106, 1966; D. H. Sadler, 19, 107, 1966; J. J. Evans, 19, 392, 1966; and to the comments in the article by H.M. Nautical Almanac Office in 19, 133 and 1 $2, 1966) and it should be unnecessary toNrestate either the principle or the practical disadvantages of this method.

The Bicentenary of the Nautical Almanac

In ‘A Modern View of Lunar Distances’ (Journal, 19, 131) H.M. Nautical Almanac Office has already covered most of the technical aspects of the method of lunar distances which the Almanac made practicable; in ‘The Foundation and Early Development of the Nautical Almanac’ (Journal, 18, 391), Dr. E. G. Forbes has given a scholarly, fully documented, account of the early history of the Almanac; and Mr. Sadler himself has written many articles on various aspects of the bicentenary. This general account, which necessarily must duplicate parts of these articles, is directed as far as practicable to those aspects that are likely to be of greatest interest to members of the Institute not technically concerned with astronomical navigation. The paper was presented, in an abridged version, at the Annual General Meeting on 25 October 1967.

The Nautical Almanac in Its Seventh Third of a Century

1967 is the bicentenary year of The Nautical Almanac and Astronomical Ephemeris, first published for the year 1767. Its origin and early history are reviewed primarily to see how the provision for astronomical navigation has been changed to meet the changing and expanding requirements of navigation. Against this background consideration is given to the changes that the increasing use of computers and other methods in terrestrial navigation, and the extension to space navigation, may bring in the last third of the twentieth century. It is concluded that little change will be required.

The Bicentenary of the Nautical Almanac (1767)

The Bicentenary of the <i>Nautical Almanac</i> (1767)

Expansions in Elliptic Motion, Constituting Volume XVIII of Astronomical Papers Prepared for the Use of the American Ephemeris and Nautical Almanac

Expansions in Elliptic Motion, Constituting Volume XVIII of Astronomical Papers Prepared for the Use of the American Ephemeris and Nautical Almanac

Use of a Small Computer as a Celestial Navigation Aid

This paper concerns use of a computational device by ships' navigation officers to improve the efficiency of celestial fix taking operations. The objectives are to reduce the demands placed on the officers' time by present manual computation procedures and to reduce the loss of night vision caused by exposure to high illumination levels. Computational procedures are defined for presetting the sextant and for determining a line of position from one sextant observation. Successive applications of the procedures for two or more sightings will provide a celestial fix. Data from the Nautical Almanac are entered into the computer by the operator via a keyboard at appropriate points in the computation sequence. A small electronic digital computer suitable for performing the necessary computations is described. Special wiring of the computer memory converts the computer from a general purpose calculation tool to a special purpose navigation device tailored to the needs of the navigation officer. However, capability is retained for using the computer in alternate modes for other shipboard functions when it is not in use for fix-taking.

デイジタル計算機による天文航法 : II 天測暦データのフーリ級数補間(日本航海学会第36回講演会)

It is desirable to get nautical almanac data from a digital computer through approximate calculation, when we fix ship's position with the computer by astronomical navigation. Fourrier series interpolation seems to be most suitable for the purpose, because right ascention and declination of a celestial body are nearly periodical functions. The author programmed formulas and calculated them with HITAC 5020E. Calculation time: About 0.005sec for R.A. (or E_*) and dec. of every fixed star, when 7 coeff. are used for each one of the factors. About 0.02sec for R.A. (or E_*), dec. and S.D. of the sun, 25 coeff. for every factor. Max. error: ±1.0sec, ±0'.1; ±1.2sec, ±0.'12, and ±1".0 respectively, where the coefficients are determined from Japanese nautical almanac (1967) data. If ephemeris data are used, maximum error will be reduced to a tenth of the above value. Recommendation: To put calculation formulas and accurate coefficients into print on a nautical almanac.