I was a bit too late with this for the NX0.5 release... but here it is, a new version of CelNav:


*** NX0.4 users please see reply to this post below ***

The biggest change over the version that comes with NX0.5 is the addition of a new "Planet Finder" tab:

The idea is to show you at a glance when which planets will be above the horizon at your location and therefore available for a fix. The original idea wasn't mine - I saw something similar in the XEphem documentation and just tweaked it a bit. Tihe light grey shaded areas indicate twilight at your location, the dark stuff is night and yellow means the planet is "up" at that time.

There are a few more changes/additions in this new version:

• The Alamanac tab has a new "Star Data" button. pressing this button will generate a csv file with SHA, declination and magnitude for the 57 navigational stars plus Polaris. The file will also list Azimuth and Altitude for these stars at the time and location entered by the user. This can be used as a simple star finder in planning a sight.
• Both the Almanac Page and the Star Data csv files now list all angular vaule in two formats. One is signed degrees with decimal fractions the other is the more humanly readable format from the Nautical ALmanac (e. g. N 30 54.3). The former is suitable for sorting, filtering or use in calculations while the latter may be handy if you wanted to printed these files as a paper reference.
• On the Almanac tab you now also find semi diameter data for Sun and Moon. Hence you can now get everything that is in the Nautical Alamanac's daily pages on this tab.
• You no longer have to specify a file name when pressing the "Almanac Page" or "Star Data" buttons. CelNav will create the csv file in a temporary directory and open it in Gnumeric without bugging you. If you want to save the file somewhere you can do so from Gnumeric with File->Save As.... The temporary directory will be removed when you close CelNav.
• Some application parameters can be configured via a new celnav.ini file that will be put into the $HOME/.celnav directory. Most notably the ini file sets the lat and lon values to which the entry fields in CelNav will be initialized when the application starts.
• The nxcn shell script (in /usr/local/bin) has been modified. Before it launches CelNav it updates the lat/lon values in celnav.ini with the current values found in /etc/nx.lat and /etc/nx.lon. Under Navigatrix these latter two files will automatically be kept up to date with your latest GPS position (provided you have a GPS plugged into your computer).
• The celnav.ini and celnav.log files can be accessed via the file menu
• The log file now has column headings so you don't have to guess anymore whether that value in column 47 was the date portion of the time of a sight or your mother's birthday.
• There now is a separate "Write Log" button on the "Sight Reduction & Fix" tab (formerly "2-LOP Fix" tab). Sight and fix data will only be logged when you press this button rather than everytime you press "Update Fix".
• There is reasonably detailed help available under the new menu.
• Big change "under the hood": While the old version used the separate aa application (part of nx) to calculate ephemeris data for stars, the new version now uses PyEphem for all ephemeris calculations. This is however configurable in the celnav.ini file. If you ever come across a descrepancy and want to revert to aa you can set the STAR_CALC parameter in celnav.ini to "aa". CelNav will log in celnav.log which value for STAR_CALC was in effect when it was launched.

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

• Unpack the attached archive into any directory
• In the file manager go to that directory and open the CelNav-0.2.0 folder that was extracted from the archive
• Press [F4] to open a terminal window in the current CelNav-0.2.0 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.
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-0.2.0 directory with more detailed set-up information.

If you install CelNav under NX0.4 (or any other non-NX Linux system) you will need to install two additional Python packages (in NX0.5 they're already part of the plumbing):

• PyEphem for ephemeris calculations:
  Attachment:
  pyephem-3.7.5.1.tar.gz [686.95 KiB]
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• PyTtk for some GUI widgets:
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  pyttk-0.3.2.tar.gz [124.28 KiB]
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Installation for these packages is analogous to the procedure for CelNav described above. Both packages also have Readme files with instructions.

CelNav is pure Python code. Feel free to change, improve, correct it as you like. Please post any ideas, comments, bugs back to this forum so everyone else can benefit as well. Thanks!

The devil's in the detail... at least for NX0.4 users.

I did come across a little snafu in the new CelNav package posted above when I tried to install it on my 'old' SD card version of NX (0.4) during a recent passage. This will only affect NX0.4 users, the version above should run fine under NX0.5.

If you install the package above (CelNav-0.2.0) under NX0.4 and then try to launch it from the "Manta Menu" it will look as if the application doesn't start. To fix this you can take the updated package CelNav-0.2.1 attached below and install it following the procedure described in the previous post. The new version will run under both, NX0.4 and NX0.5.


Here's what was wrong with the 0.2.0 version: With NX0.5 the default Python version in Navigatrix has changed from 2.6 to 2.7. CelNav-0.2.0 used a function (total_seconds() method on a datetime.timedelta object) that is available in Python 2.7 but not in 2.6. Hence no issue for NX0.5 users but a non-starter for NX0.4. The new version 0.2.1 just does "manually" what the offending function did in 0.2.0. The devil is indeed in the detail...

Worked like a charm. Keep directory names as per unpacked.
Many thanks. Will now have to calibrade the sextant