The Institute of Applied Astronomy of the Russian Academy of Sciences submits the next issue of òÀÜThe Nautical Astronomical Almanac for the years 2005-2006òÀÝ (NAA-2) biennial.

NAA-2 is based on òÀÜThe Nautical Astronomical YearbookòÀÝ (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 a marine sextant, the celestial globe, star charts and new form of fixing position plotter for determination of a ship's location.

The structure of òÀÜThe Nautical Astronomical Almanac for the years 2005-2006òÀÝ has not undergone essential changes in comparison with the previous issue of NAA-2. Thus the theoretical basis of ephemerides has undergone to radical processing. The DE200/LE200 theory of movement of bodies of Solar system has replaced on DE405/LE405, in which coordinates and speeds of objects are gave as the polynoms by Tchebyshev. 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. This reform has been made in accordance with the resolutions of XXIV General Assembly of International Astronomical Union (Manchester, 2000). Thus, consistency is achieved between the data published in NAA-2 and in Russian òÀÜThe Astronomical YearbookòÀÝ which is the basis for planning and carrying out astronomical and geodetic programs. In Explanation to òÀÜNautical Astronomical AlmanacòÀÝ the additions are made and some algorithms of calculation of ephemerical data are revised for increase their accuracy. The detailed description of theoretical basis of modern astronomical ephemerides, as well as algorithms of their calculations may be found in òÀÜThe Expanded explanation to the Astronomical YearbookòÀÝ published in òÀÜTransactions of IAA RASòÀÝ, 2004, v.10.

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 step a 5 hour 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 published.

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

The Almanac 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 moonrise and moonset to within 0.1^h according to the time of lunar culmination. There are some auxiliary tables for interpolation and calculation of altitude and azimuth in NAA-2.

Calculations of ephemerides in NAA-2 for 2005-2006 have been executed by the following researchers of Laboratory of astronomical yearbooks 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 the planets, apparent places of stars, tables of azimuths of Polaris – M.L.Sveshnikov;
• 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 time 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 (2005-2006) is revised by N.I.Glebova, M.V.Lukashova, M.L.Sveshnikov. Such paragraphs as the application of 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 new fixing position plotter. These sections have been elaborated by prof. G.A.Golubev (Admiral S.O.Makarov State Maritime Academy) for NAA-2 issue of 2002-2003.

Examples for NAA-2 are calculated by M.V.Lukashova, M.L.Sveshnikov, and N.B.Zeleznov.

The data control over various sections of NAA-2 is made by N.I.Glebova, I.A.Lebedeva, M.V.Lukashova, N.K.Omel'yanchuk and M.L.Sveshnikov.

M.V.Lukashova and M.L.Sveshnikov have made the original of the Explanation for NAA-2 with T_EX-system. Presentation of fixing position plotter and star charts in PS-format is executed by M.L.Sveshnikov and A.M.Sveshnikov. Design of the cover of the volume has been made by A.E.Nechaev. Editing version of the tables has been made by G.A.Netsvetaeva using òÀÜSystems of Making-up of Tabulated Editions SVITAòÀÝ developed in IAA RAS.

Work associated with editing the Almanac has been headed by M.V.Lukashova, Chief of Laboratory of astronomical yearbooks, with active participation of all the researchers of the Laboratory.

In conformity with the STCW95 Code provisions, every watch officer, chief mate and captain should be able to use classic methods of nautical astronomy, so they will surely appreciate the new òÀÜNautical Astronomical AlmanacòÀÝ available.

òÀÜThe Nautical Astronomical AlmanacòÀÝ has been approved by Department of Safety Navigation of the State Service of Marine (ROSMORFLOT) of Ministry of Transport of Russian Federation, and it is recommend to be used by navigators in Russian Federation.