Nautical Almanac for Celestial Navigation
The nautical almanac data from this site, is available in two forms:
An interactive form, supplying the almanac data for
six successive days of a celestial object in HTML format.
The links from the list below (see "Interactive Almanac")
will give access to these almanac tables for the selected object. A pre-compiled Nautical Almanac in PDF format, which can be
viewed and printed with e.g "Acrobat Reader" ,"Xpdf"
or "Evince".
The pre-compiled Nautical Almanac can be downloaded from the
links further below (see "Pre-compiled Almanacs").
Please notice that the almanac data made available here is
intended for exercising purposes.
Almanac data is available for the Sun, Moon, Venus, Mars, Jupiter and Saturn.
Other celestial objects, especially the stars are not so well suited
for celestial navigation on a sailing vessel.
Keep in mind that in order to be useful for Celestial Navigation,
both the horizon and the celestial object have to be clearly visible.
This can only be obtained for a few of the brightest stars such
as Sirius (α-Canis-Major) or Canopus (α-Carinae).
Therefore, data for the "First Point of Aries" and some selected stars
is available only as a separate compiled manual and is not included in the
standard Nautical Almanac.
NOTICE on the data format of the Almanacs:
For the interpolation of integral-hour values of the Greenwich Hour Angles
and Declination, a slightly different approach than the one usually used in
commercial Nautical Almanacs is used here in order to obtain a (slightly)
better accuracy and to obtain a uniform calculation scheme for all celestial objects.
Please refer to the
notes on linear interpolation
for more information.
Tables
Interactive Almanac
Pre-compiled Nautical Almanac
The Nautical Almanac may also be downloaded as 'printer-ready' PDF manual.
In order to reduce web traffic and download cost, the pre-compiled Nautical
Almanac is divided into 5 sections.
The first section contains some general information on terms and usage,
an overview of the Lunar Phases for the covered year as well as
information on special astronomical events such as Solar and Lunar Eclipses.
Also included in the first part are simple star maps showing the positions
of the planets for each month of the year.
These maps may simplify the tracing of the planets on the morning and
evening sky.
The intrinsic almanac data is divided over four quarterly-based volumes
each part containing the ephemerides for three successive months.
The star data is made available in a separate manual including star maps
the data for the position of the "First Point of Aries" and the coordinates
of a set of selected stars.
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The pre-compiled Nautical Almanac for the current and the following
year is available from the
"Download Section". |
Background Information
The Nautical Almanac data available here are based on calculations done
with the software package "NOVAS" from the
U.S. Naval Observatory.
The basic ephemerides are taken from the "DE405" files published by
the
Jet Propulsion Laboratory.
More information including a link to the source codes I used
for this project are available on the page
"Notes on the C-programs used to calculate the Ephemerides".
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