scholarly journals Note on the Nautical Almanac Values of the Semidiameters of the Sun and Venus used in the calculations of the Transit of Venus

1873 ◽  
Vol 33 (5) ◽  
pp. 293-294
Author(s):  
Edwin Dunkin
Keyword(s):  
The Sun ◽  
Nautical Almanac

The New Abridged Nautical Almanac

1951 ◽  
Vol 4 (04) ◽  
pp. 377-385
Keyword(s):  
Present Form ◽  
Transitional Period ◽  
The Sun ◽  
American Spanish ◽  
Detailed Work ◽  
Right Ascension ◽  
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.

scholarly journals Graphical Methods of Finding the Sun's Azimuth and Elevation

1963 ◽  
Vol 16 (3) ◽  
pp. 369-374
Author(s):  
D. H. Shinn
Keyword(s):  
Radiation Pattern ◽  
Vertical Plane ◽  
Graphical Form ◽  
Graphical Methods ◽  
The Sun ◽  
Simple Method ◽  
The Mean ◽  
Nautical Almanac ◽  
Local Noon

Like Mr. R. S. Blicq (Journal 15,456) we have also been concerned in supplying details of the Sun's position to engineers on radar sites who use radiation from the Sun for, at present, two purposes:(a) Measuring or checking the radiation pattern of the aerial in the vertical plane.(b) Lining up the aerial in azimuth or elevation.For these purposes the required accuracy of computation is usually about ±0°·1 in azimuth and elevation. Greater accuracy is never required, but less accuracy is sometimes adequate, up to ±1°.We have found that graphical methods appeal most to engineers, and that even when a full table of values is supplied to them they prefer to display this information in graphical form. We have accordingly evolved a simple method of constructing graphs of elevation against time, and azimuth against time.In order to achieve the required accuracy of ±0°·1 in elevation we have constructed a graticule of size 21 in. × 40 in. A skeleton version of this is shown in Fig. 1. The engineer has to know his latitude, and to find, from the Nautical Almanac or other source, the time of local noon (i.e. when the Sun is due south) and the mean declination, δ, of the Sun during the period of observation, which usually lasts up to three hours.

scholarly journals Remarks on a correction of the solar tables required by Mr. South’s observations

1833 ◽  
Vol 2 ◽  
pp. 305-305
Keyword(s):  
The Sun ◽  
Peculiar Form ◽  
The Mean ◽  
Right Ascension ◽  
Nautical Almanac

The discordancies observed by Mr. South between the sun’s right ascension, as deduced from observation, and those given in the Nautical Almanac, follow a law so simple as not to allow of their being regarded as errors of observation, or arising from any casual cause, but justify us in attributing them to imperfections in the solar tables, with the exception of three days, in which there seems to be some ground to suspect error of computation. A single inspection of these discrepancies, Mr. Airy observes, suffices to show that they arise almost entirely from an error in the epoch, and an error in the place of the perigee. From the peculiar form of the tables in Vince’s Astronomy, which give great facility to the introduction of an error in the excentricity, he was induced at first to suspect that one might exist; but on calculation found the error in the equation of the centre so small as to be entirely insensible. He then proceeds to detail the process by which, from Mr. South’s observations, he has deduced the amount of the several errors, which consist in regarding the epoch, the mean anomaly, and the equation of the centre, as erroneous by three very small unknown quantities, and forming as many equations of condition for determining them as there are observations. These combined and resolved, so as to give the most probable result, lead to the conclusions, first, that the correction of the equation of the centre is evanescent; secondly, that the epochs of the sun must all be increased by 9", and the epochs of the perigee each by 1' 48".

Appendix: Reports of the Directors of the National Ephemerides

1970 ◽  
Vol 14 (1) ◽  
pp. 5-9
Author(s):  
V. K. Abalakin ◽  
J. Kovalevsky ◽  
D. H. Sadler ◽  
W. Fricke ◽  
A. M. Sinzi ◽  
...  
Keyword(s):  
The Sun ◽  
Lunar Crater ◽  
Royal Greenwich Observatory ◽  
Proper Motions ◽  
Lunar Ephemeris ◽  
Differential Corrections ◽  
Nautical Almanac ◽  
Astronomical Constants

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.

2. Solar Eclipse, 31st December 1880

1882 ◽  
Vol 11 ◽  
pp. 18-19
Author(s):  
E. Sang
Keyword(s):  
Solar Eclipse ◽  
The Sun ◽  
Actual Observation ◽  
Lunar Ephemeris ◽  
The Times ◽  
The Right ◽  
Right Ascension ◽  
Nautical Almanac

The elements for the compution of eclipses are given in the “Nautical Almanac” with precision sufficient for all ordinary purposes; but, when we wish to compare the lunar ephemeris with actual observation for the purpose of verifying or of improving our data, we must go somewhat more minutely into the investigation.Thus, in the List of Elements, p. 403, the changes in the right-ascension and declination of the sun and moon are supposed to be proportional to the times, while the moon's geocentric semidiameter, as well as the horizontal parallax, is supposed to be constant during the eclipse. In this way some exceedingly small errors are introduced into the calculation.

Astronomical observations

1833 ◽  
Vol 2 ◽  
pp. 135-135
Keyword(s):  
Direct Method ◽  
The Sun ◽  
Vernal Equinox ◽  
Astronomical Observations ◽  
The World ◽  
The Mean ◽  
The Right ◽  
Right Ascension ◽  
Nautical Almanac

In the present improved state of astronomical observations, it is material to possess the readiest and most accurate means of finding the apparent time. The right ascension of certain fixed stars having been precisely obtained relatively with each other, and with the equinoctial points during the course of many years, affords the direct method of ascertaining the right ascension of the mid-heaven: hence the convenience of having the corrections of these stars in the form of tables, that the same may be taken out at one view with the arguments of the sun’s longitude, and of the moon’s node. For this purpose the mean diurnal motion is adapted to the longitude of the sun, as found in the Nautical Almanac, at the time the star passes the meridian. The mean epoch is reduced to the vernal equinox less four seconds, in order to render the corrections additive; which, being an universal period, the same applies to all parts of the world. To these tables Mr. Groombridge has subjoined some observations of the planets at and near the oppositions; also of the solstices of the last two years, and of the comet of 1819.

scholarly journals Irradiation: A Note

1974 ◽  
Vol 27 (2) ◽  
pp. 261-265
Author(s):  
Charles H. Cotter
Keyword(s):  
Upper Limb ◽  
The Sun ◽  
Considerable Time ◽  
Considerable Contribution ◽  
Correction Table ◽  
Nautical Almanac

It is some considerable time since the questions associated with irradiation were considered in the pages of the Journal. Indeed the interesting and practical paper by Captain Brett Hilder is the latest considerable contribution to the Journal and this appeared no less than twenty years ago. It is only in comparatively recent times that nautical astronomers have been provided with an authoritative irradiation correction of any sort. This, which applies only to observations of the Sun's upper limb, was incorporated in the altitude correction table for the Sun and appeared annually in the Nautical Almanac after 1953, the year of Hilder's paper, but was discontinued after 1969.

scholarly journals III. On the corrections in the elements of Delambre’s solar tables required by the observations made at the Royal Observatory, Greenwich

1828 ◽  
Vol 118 ◽  
pp. 23-34
Keyword(s):  
Royal Society ◽  
The State ◽  
The Sun ◽  
Remarkable Difference ◽  
Royal Observatory ◽  
Laborious Work ◽  
Nautical Almanac

The attention of the Board of Longitude having been directed to the state of the Solar Tables used in the construction of the Nautical Almanac, the Astronomer Royal was requested to furnish the Board with a comparison of the computed and observed Right Ascensions of the Sun since the erection of the new transit instrument at Greenwich : and I was desired to examine the discrepancies with a view to the discovery of the errors in the elements of the tables. The papers containing this comparison I received at the beginning of June last; and in the last summer, as soon as other engagements permitted, I undertook the laborious work of examining the discordances. The corrections of the elements determined by these calculations agree in general with those that have been obtained from other observations ; but in one particular, and that an important one, there is a very remarkable difference. The results of such an inquiry will perhaps be acceptable to the Royal Society ; and the singularity of the conclusion which I have mentioned, will make it necessary for me to describe the manner in which I have obtained it.

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