Creates the daily pages of a Nautical Almanac using Ephem
Project description
Pyalmanac is a Python 3 script that creates the daily pages of the Nautical Almanac using the UTC timescale, which is the basis for the worldwide system of civil time. Official Nautical Almanacs employ a UT timescale (equivalent to UT1).
The ‘daily pages’ are tables that are needed for celestial navigation with a sextant. Although you are strongly advised to purchase the official Nautical Almanac, this program will reproduce the tables with no warranty or guarantee of accuracy.
Pyalmanac was developed based on the original Pyalmanac by Enno Rodegerdts. Various improvements, enhancements and bugfixes have been added since.
This is the PyPI edition of Pyalmanac-Py3 (a Changelog can be viewed here). Version numbering follows the scheme Major.Minor.Patch, whereby the Patch number represents some small correction to the intended release.
Current state of Pyalmanac
Pyalmanac is a somewhat dated program. Pyalmanac is implemented using the Ephem astronomical library (originally named PyEphem), which has Mature development status. Ephem was based upon XEphem, which is ‘end of life’ as no further updates to XEphem are planned. Elwood Charles Downey, the author of XEphem, generously gave permission for their use in (Py)Ephem.
Pyalmanac contains its own star database, now updated with data from the Hipparcos Star Catalogue. Star names are chosen to comply with official Nautical Almanacs. The GHA/Dec star data now matches a sample page from a Nautical Almanac typically to within 0°0.1’. As of now, (Py)Ephem will continue to receive critical bugfixes and be ported to each new version of Python. Pyalmanac still has the advantage of speed over other implementations.
One minor limitation of Ephem is in the EOP (Earth Orientation Parameters) (affecting sidereal time) which is more accurate in Skyfield-based almanacs as they can employ the IERS (International Earth Rotation Service) EOP published data. This affects sidereal time, which minimizes GHA discrepancies (for all celestial objects) in general.
Given the choice, SFalmanac is an up-to-date program with more enhanced functionality compared to Pyalmanac, and it uses Skyfield, a modern astronomical library based on the highly accurate algorithms employed in the NASA JPL HORIZONS System. (Pyalmanac and SFalmanac have same formatted pages so differences can easily be spotted by swiching between them in Adobe Acrobat Reader.)
Software Requirements
python >= 3.4 (the latest version is recommended)
ephem >= 3.7.6 (4.1 is good; 4.1.1, 4.1.2 and 4.1.3 are faulty)
The fault with Ephem 4.1.1, 4.1.2 or 4.1.3 is an Endless loop in computing moon rise/set
Installation
Install a TeX/LaTeX program on your operating system so that ‘pdflatex’ is available.
Ensure that the pip Python installer tool is installed. Then ensure that old versions of PyEphem, Ephem and Pyalmanac are not installed before installing SkyAlmanac from PyPI:
python -m pip uninstall pyephem ephem pyalmanac python -m pip install pyalmanac
Thereafter run it with:
python -m pyalmanac
On a POSIX system (Linux or Mac OS), use python3 instead of python above.
This PyPI edition also supports installing and running in a venv virtual environment. Finally check or change the settings in config.py. It’s location is printed immediately whenever Pyalmanac runs.
Guidelines for Linux & Mac OS
Quote from Chris Johnson:
It’s best to not use the system-provided Python directly. Leave that one alone since the OS can change it in undesired ways.
The best practice is to configure your own Python version(s) and manage them on a per-project basis using venv (for Python 3). This eliminates all dependency on the system-provided Python version, and also isolates each project from other projects on the machine.
Each project can have a different Python point version if needed, and gets its own site_packages directory so pip-installed libraries can also have different versions by project. This approach is a major problem-avoider.
Troubleshooting
If using MiKTeX 21 or higher, executing ‘option 7’ (Increments and Corrections) it will probably fail with:
! TeX capacity exceeded, sorry [main memory size=3000000].
To resolve this problem (assuming MiKTeX has been installed for all users), open a Command Prompt as Administrator and enter:
initexmf --admin --edit-config-file=pdflatex
This opens pdflatex.ini in Notepad. Add the following line:
extra_mem_top = 1000000
and save the file. Problem solved. For more details look here.
Project details
Release history Release notifications | RSS feed
Download files
Download the file for your platform. If you're not sure which to choose, learn more about installing packages.
Source Distribution
Built Distribution
Hashes for pyalmanac-1.4.3-py3-none-any.whl
Algorithm | Hash digest | |
---|---|---|
SHA256 | 77fb7c3e16338ac3b14220206a50b279c7b73acfbeba28870d054ee3a1e42e1e |
|
MD5 | 11f61f2fb6a7892c402a4ff45eec6b5a |
|
BLAKE2b-256 | 0805f2c6edc1f7abf47933a1f52434c46c9080adab35bfa572f98520be5c612c |