Nautical Almanac Research Articles

A Device to Determine Position Rapidly Without Calculation

The problem of the determination of the observer's position on the Earth can be most easily solved in terms of the equatorial coordinates of the observer's zenith. From Fig. 1, in which the inner circle represents the Earth and the outer circle the celestial sphere, it can be seen that the zenithal point on the celestial sphere is its intersection with the prolongation of the radius to the observer's position. The geographical latitude of the observer is equal to the declination of the observer's zenith, and the geographical longitude is equal to the difference between Greenwich sidereal time (G.S.T.) and the right ascension of the observer's zenith. We can obtain G.S.T. by interpolation from a nautical almanac or directly from a separate watch or clock set to keep sidereal time.

American Ephemeris and Nautical Almanac

American Ephemeris and Nautical Almanac

Methods of Astronomical Navigation

I think the Institute is doing a grand job in this matter of getting to the bottom of what actually happens at sea. I give a personal ‘shabash’ to D. H. Sadler & Co. for the new Abridged Nautical Almanac, and to S. M. Burton for the first-ever really practical manual and tables, but I am now completely ‘sold’ on H.D. 486 [Tables of Computed Altitude and Azimuth] and have very little to look forward to unless it be my dream of ‘a small hopper, into which one throws two or more altitudes, turns a handle, and tears off a neatly printed position’. I can see no loss of caste to seamen in this. All I ever did know about a haversine, for example, was that it contained a conglomeration of figures which when conjoined with others, cosines and suchlike, led by tortuous and unseamanlike stages to a position line on a chart. I never felt the slightest bump when crossing over to H.D. 486, where all those abominable spherical trigonometrical triangles have already been worked out by experts who, I understand, really like 'em. So roll out that hopper.

The Barcoo Observations

In the course of a survey of the Arafura Sea by H.M.A.S. Barcoo, many astronomical observations were made under good, and controlled, conditions; through the courtesy of the Admiralty these observations have been made available for analysis. This analysis has been regarded as a pilot investigation for the working party on the accuracy of astronomical observations at sea. Its main, crude, result gives (from these observations) a standard deviation of a single observation as 1.1.During the latter half of 1952, H.M.A.S Barcoo was engaged in surveying an area, 200 miles by 30, in the Arafura Sea some 50 miles north-west of Cape Wessel. Seven fleets of beacons were laid out, each consisting of about 14 beacons at intervals of about 5 miles. The first beacon of each fleet was used as a datum beacon and its position determined by astronomical observations by three observers, both morning and evening on two days; each observer took as many stars as possible on each occasion and the mean of three or four shots of each star. The datum beacons were connected by taut-wire runs and it was found that the taut-wire distances were not in agreement with the mean positions determined from the astronomical observations. It was primarily for this reason that the observations were carefully collated by Lieutenant J. M. Child, R.N., and forwarded to the Admiralty. The observations were in due course sent to H.M. Nautical Almanac Office, where it was decided to subject them to a detailed statistical analysis. They are not suitable for inclusion in the (deliberately) heterogeneous observations being collected for the working party of the Institute on the accuracy of astronomical observations at sea; but they provide the ideal material for a pilot investigation into methods of analysis.

Thomas Young, Natural Philosopher

List of plates List of illustrations in the text Alex Wood - a memoir Charles E. Raven Preface Acknowledgements 1. Early years, 1733-92 2. Medical study in London and Edinburgh, 1792-4 3. Medical study in Gottingen and Cambridge, 1795-9 4. Physician and medical author 5. The human eye 6. Professor at the Royal Institution 7. The wave theory of light is founded 8. Theory of light 9. The Rosetta Stone 10. Rival claims of Young and Champollion 11. The Encyclopaedia Britannica (1917-25) 12. Herculaneum and languages 13. Standards of length, Young and the Admiralty, life assurance 14. Nautical almanac and board of longitude 15. Events in later life Appendix Index of names Index of subjects.

The Accuracy of Astronomical Observations at Sea

It was with some surprise that I read Commander Sharpey-Schafer's ‘Some Notes on Astronomical Observations at Sea’ (this Journal, Vol. VI, p. 362), especially his conclusions regarding the fixing accuracy obtainable with marine sextant observations. I can makeno claim to be an experienced navigator myself, but, as a member of the staff of H.M. Nautical Almanac Office, I was privileged, in 1949, to spend three months as an observer on board H.M.S. Dalrymple, a newly-commissioned surveying ship, under the command of Captain (now Vice-Admiral Sir) A. Day.

The Size of Navigation Tables

In his review of Sight Reduction Tables for Air Navigation (A.P. 3270) on page 98, Mr. J. B. Parker suggests that navigators might tolerate the disadvantage of tables with large intervals in the arguments. Mr. D. H. Sadler, Superintendent of H.M. Nautical Almanac Office, comments on this suggestion as follows:Mr. Parker's suggestion is most intriguing. A substantial reduction in bulk would be possible, as the following table of approximate figures shows.

Computing the Revised Edition of H.O. 249 (A.P. 3270)

The new U.S. Hydrographic Office publication H.O. 249, Sight Reduction Tables for Air Navigation, comprises three volumes: Volume I covers all latitudes and contains tables of altitude and azimuth of selected navigational stars; Volume II contains tables of computed altitude and azimuth angle for latitudes 0°–39°, declinations 0°–29°; and Volume III contains tables of computed altitude and azimuth angle for latitudes 40°–89°, declinations 0°–29°. The tables have been produced jointly by the American Nautical Almanac Office and H.M. Nautical Almanac Office for the U.S. Hydrographic Office. The British edition of the tables is being published by H.M. Stationery Office as A.P. (Air Publication) 3270; the actual tables are identical with the American edition but the introductory matter has been reset.

The Abridged Nautical Almanac for 1954

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I—Thomas Hariot's Manuscript

In a previous article in this Journal mention was made of an unexamined manuscript by Hariot belonging to the Petworth Collection entitled The Doctrine of Nauticall Triangles Compendious, which promised to be of interest to navigators. When Lord Leconfield, the owner of the Collection, heard of this he very kindly himself brought this manuscript to the British Museum for study there, and meanwhile Dr. Shirley of the United States, who is at work on other aspects of Hariot's life, sent over from America a transcript from a microfilm copy which was in his possession. The contents of the manuscript more than fulfilled expectation, for it appeared that the main theme was the computation of meridional parts for drawing a Mercator chart and, as Mr. Sadler, the Superintendent of H.M. Nautical Almanac Office, shows in the second part of this paper, Hariot was remarkably in advance of his time in his mathematical treatment of this problem, which continued to be a favourite one for discussion until the discovery of the calculus. As is well known, the first table of meridional parts to be published was that compiled (by simple addition of secants) by Edward Wright (1558–1615) of Caius College, Cambridge, a mathematician who had been nautical adviser to the Earl of Cumberland, and on occasion to the Lord High Admiral himself.

SELECTED STARS 1953 ALMANACS

Through the cooperation of the U.S. Nautical Almanac Office and Her Majesty’s Nautical Almanac Office, Selected Stars have been chosen to be used in both the Nautical and Air navigational stars previously listed. It can be seen that careful attention has been given both to the brightness and distribution of the stars selected. Beta Crucis, Caph, Dschubba, Mitar, Ruchbah and Polaris have been omitted from the 1752 star list. Ankaa, Gienah, Hadar, Mekar, Schedar and Zubenelgenubi have been substituted. Data for Polaris, as usual, are given on a special page. The reason for selecting exactly stars, as before, is not clear except that such number is, in general, adequate for navigational purposes. It might be noted that there are lines available on the page and then there is the American precedent in the 57 varieties.

BOOK REVIEWS

NAVIGATIONVolume 3, Issue 6 p. 213-217 BOOK REVIEWS First published: December 1952 https://doi.org/10.1002/j.2161-4296.1952.tb00653.xAboutPDF 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 Abstract Book reviewed in this article: PRIMER OF NAVIGATION; THIRD EDITION; George W. Mixter, Revised by Ramon O. Williams; D. Van. THE ABRIDGED NAUTICAL ALMANAC FOR THE YEAR 1952: His Majesty's Stationery Office. THE PRINCIPLES OF THE CONTROL AND STABILITY OF AIRCRAFT; W. J. Duncan D.Sc. F.R.S. Volume3, Issue6December 1952Pages 213-217 RelatedInformation

THE INSTITUTE OF NAVIGATION

society, the Institute of Navigation, devoted to the advancement of the science of navigation on the sea and in the air. Those in attendance who became charter members of the organization include outstanding representatives of many fields associated with navigation. Meteorologists, cartographers, the Army Air Forces, the Nautical Almanac Office, the astronomical observatories, the United States Power Squadron, the U.S. Coast and Geodetic Survey, the Hydrographie Office of the Navy, the Navy Air Corps, the aircraft manufacturers, the manufacturers of navigational instruments, the commercial airlines, and writers on and teachers of navigation were all liberally represented in the roster. The representatives of the observatories were : Dr. Seth B. Nicholson, Dr. R. S. Richardson, and Mrs. Elizabeth S. Mulders, Mount Wilson Observatory; Dr. G. F. W. Mulders, Occidental College; G. M. Clemence, United States Naval Observatory; Dr. C. H. Cleminshaw, Griffith Observatory; Dr. Charles H. Smiley, Ladd Observatory, Brown University ; Dr. F. J. Neubauer, Lick Observatory ; and Dr. Samuel Herrick.

Chauncey Wright: Forgotten American Philosopher

CHAUNCEY WRIGHT's analyses of the structure and methods of science were probably even more penetrating than those of John Stuart Mill; his precise characterization of English empiricism was an equally important achievement in general philosophy. In empirical psychology he introduced the Darwinian concepts of minute variation and natural selection to account for the origin of self-consciousness, but only recently has the historical importance of his writings been at all recognized, and even then chiefly by writers who share the view that he anticipated the philosophy known as pragmatism.' The neglect of so important a figure in the history of American thought may in part be explained by Wright's retiring personality and unsensational career. In his autobiographical sketch for the Harvard Class Book of 1858 Wright wrote, the earliest period of my conscious life I have shrunk from everything of a startling or dramatic character. I was indisposed to active exercise, to any kind of excitement or change. That this attitude persisted is evident from the uneventful character of his later life. From 1852 to 1870 he was a computer for the Nautical Almanac; he lectured twice at Harvard College-in psychology in 1870 and mathematical physics in 1874-and occasionally tutored private pupils; in 1860 he was elected a fellow of the Academy of Arts and Sciences; he visited Darwin in England in 1872; and between 1864 and 1875 he contributed numerous articles to the North American Review and the Nation.

The New Abridged Nautical Almanac

TheAbridged Nautical Almanacin its revised form, for the year 1952, has now appeared. In place of right ascension and the familiar quantitiesEandRwhich were adopted in 1929, it tabulates Greenwich hour angle in arc for the Sun, Moon, planets and Aries, and sidereal hour angle (or versed ascension) for the stars.Greenwich hourangle has been used in air almanacs for a number of years, and several surface almanacs have tabulated it as an alternative to right ascension; it is only recently, however, that it has been given exclusively in surface almanacs. Among the surface almanacs which tabulate G.H.A. at present are the American, Spanish, Argentine, Brazilian and Yugoslav.The redesign of theAbridged Nautical Almanachas been under consideration for many years, but the change was delayed first by the war, and then by the desire to avoid a transitional period during which the new G.H.A. andEandRwere given together; it was also decided to give as much notice of the proposed changes to users as possible. The design in substantially its present form was in fact accomplished in 1947, though the arrangement of the daily pages and much detailed work was carried out later.

Unification of the Air Almanac and the American Air Almanac

As from 1953 theAir Almanacand theAmerican Air Almanacwill become a single publication, under the title of theAir Almanac. It will be produced jointly by H.M. Nautical Almanac Office of the Royal Greenwich Observatory, Herstmonceux, and the Nautical Almanac Office of the U.S. Naval Observatory in Washington, to meet the general requirements for air navigation in the United Kingdom, the United States and Canada. TheAir Almanacwill be printed and published separately in the United Kingdom and the United States but the two publications will otherwise be identical.

The Abridged Nautical Almanac

The Abridged Nautical Almanac

An Almanac for Surveyors - The Star Almanac for Land Surveyors for the year 1951, prepared by H.M. Nautical Almanac Office. H.M. Stationery Office, 1950. 3s.

An Almanac for Surveyors - The Star Almanac for Land Surveyors for the year 1951, prepared by H.M. Nautical Almanac Office. H.M. Stationery Office, 1950. 3<i>s</i>.

Calculation of the shadow path of a chosen lunar feature during an occultation.

view Abstract Citations References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Calculation of the shadow path of a chosen lunar feature during an occultation. Moser, Nora B. Abstract had two serious limitations: the inaccuracy of visual observation and the influence of limb irregularities. As a development of A. E. Whitford's photoelectric measurements of stellar diameters, mobile equipment has been designed to observe an occultation photoelectrically and record it alongside radio time signals to thousandths of a second. To cancel out the effect of limb irregularities, a prominent lunar feature which will dominate the limb for several hours is selected and two or more observation posts are so placed that at each the star will disappear behind the chosen feature. A suitable occultation having been chosen, Hayn's selenographic coordinates of the edge of the moon as presented to the earth at a given time are computed by Watts' method.i The results are plotted on Hayn's contour charts of the limb region, and a prominent mountain within about 20 of the edge line is picked. The selenographic coordinates of the top of this mountain, together with more or less arbitrary times, will be the starting data for computing the shadow path along which the mountain will occult the star. To obtain maximum precision, the moon s positions, tabulated with an extra decimal place, are requested from the British Nautical Almanac Office, and the earth's selenographic coordinates (librations) are computed from basic formulas rather than interpolated from published tables. The path of the shadow axis on Bessel's fundamental plane is calculated by standard formulas. Some significant figures are lost in subtraction in this process but the relative error between points on the shadow path will be negligible. The geocentric earth's selenographic coordinates and position angle of the moon s axis are referred to the shadow axis by Watts' method for selenographic coordinates, avoiding his approximations. The selenographic coordinates of the shadow axis and of the chosen mountain are transformed to one set of rectangular coordinates fixed in the moon and then projected onto the fundamental plane, resulting in the shadow path of the mountain. Bessel's device of a parametric declination is employed in transferring the path to the earth's surface. The observation positions are tied into the U. S. first-order triangulation and may be assumed correct. The error in the moon's place will be sensibly constant during one occultation. The limb error is under control. An observation equation may be set up to solve for the correction to the lunar parallax. Acknowledgments. Walter D. Lambert of the U. S. Coast and Geodetic Survey and C. B. Watts of the U. S. Naval Observatory have furnished valuable assistance in this project. Dr. John A. O'Keefe and Mrs. Rose L. Rowen of the Army Map Service had a large part in the work described. I.A. J. 48, 170, 1940. U.S. A rmy Map Service, Washington, D. C. Publication: The Astronomical Journal Pub Date: April 1950 DOI: 10.1086/106348 Bibcode: 1950AJ.....55...75M full text sources ADS |

17. Commission Du Mouvement Et De La Figure De La Lune

The discussions of observations of occultations have been published annually in the Astronomical Journal. The publication, dealing with the observations in the year 1942, which appeared in A. J. 51, 144–5 (1945), concludes the series of annual discussions made at the Yale Observatory. Beginning with the observations in the year 1943, the British Nautical Almanac Office has assumed the responsibility for the reduction and discussion of occultations of stars by the Moon.A discussion of the Moon’s motion based upon about 5000 occultations in the eleven years, 1932–42, and about 1000 Washington meridian circle observations in the years 1933–44 was made by D. Brouwer and A. J. Watts, A. J. 52, 169–76 (1947). Both series were reduced to the FK3 system and corrections for limb error were applied, based upon Hayn’s charts. In the case of the occultations the tables by Watts, A. J. 48, 170 (1940), were used for a partial elimination of the systematic limb effect from the lunation solutions. The meridian circle observations were corrected individually.