Nautical Astronomical Almanac, 2019-2020

Preface

The Institute of Applied Astronomy of the RAS (IAA RAS) submits the next issue of "The Nautical Astronomical Almanac for the years 2019-2020" biennial (NAA-2).

NAA-2 is based on "The Nautical Astronomical Yearbook" (NAY) also prepared by IAA RAS. NAA-2 provides an easy access to a useful navigational publication which is constantly present aboard a ship and has a longer period of validity as compared to standard navigational manuals. The Almanac does not require any other publications for observation processing and gives the same accuracy of basic astronomical parameters as NAY does. NAA-2 contains detailed algorithms of solving the main navigational tasks, such as determination of the compass' correction and finding a ship's position by means of the Sun's and stars' observations. It also contains instructions for the use of the marine sextant, the celestial globe, star charts and the fixing position plotter for the determination of a ship's location.

The structure of "The Nautical Astronomical Almanac for the years 2019-2020" has not undergone essential changes in comparison with the previous issue of NAA-2. The theoretical basis of ephemerides is the EPM2011/m theory of movement of the Solar system bodies created in IAA RAS. In accordance with the resolutions of XXIV and XXV General Assemblies of International Astronomical Union positions of stars are published in the system of FK6 and HIPPARCOS catalogues referred to International Celestial Reference System (ICRS) based on the observations of extragalactic radio-sources. Thus, consistency is achieved between the data published in NAA-2 and Russian "The Astronomical Yearbook" which is the basis for planning and carrying out astronomical and geodetic programs. The Explanation and part of auxiliary tables are given in both Russian and English versions. The detailed description of theoretical basis of modern astronomical ephemerides, as well as algorithms for their calculation may be found in "The Expanded explanation to the Astronomical Yearbook" published in "Transactions of IAA RAS", 2004, v.10 (in Russian).

The basic contents of the Almanac are daily tables. They include ephemerides of hour angles of the first point of Aries, the Sun and the Moon, declinations of the Sun and the Moon for each hour, and also hour angles and declinations of planets (Venus, Mars, Jupiter and Saturn) with a 5 hour step and to within 0.1'. Besides, time of sunrises and sunsets are given for 68 values of latitude. Azimuths of the upper limb of the Sun for risings and the opportunity time of the beginning of morning and evening observations of stars are also included.

The apparent places of 160 navigational stars are given for the beginning of each month in a special table, with the apparent places of 77 brightest stars being available in daily tables for every three days of a year (accuracy 0.1'). The tables of azimuths of Polaris (Pole star) are given with accuracy 0.1°.

NAA-2 contains brief data on solar and lunar eclipses, configurations of planets, phases of the Moon and dates of the beginning of astronomical seasons. It also contains tables for the calculation of time of moonrises and moonsets to within 0.1h according to the time of lunar culmination and latitude of the observer. There are some auxiliary tables for interpolation and calculation of altitude and azimuth in NAA-2.

Calculations of ephemerides in NAA-2 for 2019-2020 have been executed by the following researchers of Laboratory of Astronomical Yearbooks of IAA RAS:

• hour angles of the first point of Aries, coordinates of the Sun, Moon, and planets, the moments of culminations, parallaxes, visible semi-diameters and phases of the Moon, configurations of planets, the beginnings of seasons - N.I.Glebova;

• conditions of visibility of planets, apparent places of stars, tables of azimuths of Polaris - M.L.Sveshnikov, G.A. Kosmodamianskij;

• the time of sunrises and sunsets, azimuths of the upper limb of the Sun for the time of sunrise, the time of the beginning of morning and evening observations, tables of corrections to the times of the culmination of the Moon for calculation of moonrises and moonsets, eclipses of the Sun and the Moon - M.V.Lukashova.

The Explanation for NAA-2 (2019-2020) is revised by M.V. Lukashova, G.A. Kosmodamianskij. Such issues as the application of the marine sextant, the use of the celestial globe and star charts are also included into NAA-2, as well as the universal altitude correction form and a fixing position plotter. Examples for NAA-2 are calculated by M.V. Lukashova, M.L. Sveshnikov, G.A. Kosmodamianskij. The data control over various sections of NAA-2 is made by G.A. Kosmodamianskij, N.I. Glebova, M.V. Lukashova, M.L. Sveshnikov, I.A. Lebedeva, and N.K. Omel'yanchuk.

G.A. Kosmodamianskij, M.V. Lukashova have prepared the original of the Explanation for NAA-2. Presentation of the fixing position plotter, star charts and diagrams of visibility of planets in PS-format is made by M.L.Sveshnikov. Editing version of the tables has been made by D.A. Ryzhkova using systems of making-up tabulated editions "PUBLISHER" developed in IAA RAS.

The work of editing the Almanac has been headed by G.A. Kosmodamianskij, editor-in-chief, with active participation of all the researchers of the Laboratory.

In IAA RAS within the framework of creation of the electronic version of NAA-2 the first version of the remote access system of "The Navigator" is developed. It is intended for the solving basic astronavigation tasks included in the explanations of NAA-2. The solving of tasks is carried out in accordance with the accepted in this edition accuracy (0.1') and format of protocols of the solutions for examples published in it (M.V.Lukashova, M.L.Sveshnikov, G.A. Kosmodamianskij). The system "The Navigator" is available from the Internet: http://shturman.ipa.nw.ru.

In conformity with the STCW-95 Code provisions, every navigator should be able to use classic methods of Nautical Astronomy. Therefore, they will undoubtedly appreciate the new "Nautical Astronomical Almanac" presented.

"The Nautical Astronomical Almanac" has been approved by Department of Navigation Safety of the State Marine Fleet Service (ROSMORFLOT) of Ministry of Transport of the Russian Federation, and it is recommended for navigators in the Russian Federation.

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