An update for the CelNav application that is part of Navigatrix' Navigation menu.


What has changed?

• Improved accuracy for GHA Aries: The new version uses the sidereal_time method of PyEphem's Observer object rather than the formula from chapter 15 in Henning Umland's A Short Introduction to Celestial Navigation. The difference between the two methods is small (< 1 arc minute), so it was more of a nuisance than a navigational issue. In any case, the new values for GHA Aries now match the values published in the Nautical Almanac.
  
• Change in semi diameter calculation for Sun and Moon from topocentric to geocentric so that the displayed values now match the Nautical Almanac. Again. more of a nuisance than a navigational issue in the old version.

Installation

Installation of the new version under Navigatrix should be straight forward:

• Unpack the attached archive above into any directory
• In the file manager go to that directory and open the CelNav-0.2.2 folder that was extracted from the archive
• Press [F4] to open a terminal window in the current CelNav-0.2.2 directory
• At the command prompt enter
  
  Code:
  sudo python setup.py install
  
  You will be asked to enter your password and then the setup script does a little magic.

That's it. when it's done, selecting Manta Menu -> Navigation -> CelNav should now launch the new version. The ini, cfg, log and error files will be in $HOME/.celnav.

You can tell that the new version is running by checking the version in the applications title bar:


The files for the old version will not be overwritten but renamed with an additional ".old" extension (the setup script will actually print a message for each file that is renamed/moved). So you can revert to the old version in case something goes horibbly wrong during installation. There also is a README file in the CelNav-0.2.2 directory with more detailed set-up information.

The archive and the extraction directory can be removed after installation.