Automated Solar Altitude stamps on NLC images

[noctal]

Hi there, here is a free Perl-based tool for NLC analysis that you might find useful or interesting, especially for time-lapses.
sites.google.com/site/alistargazing/articles/solar-altitude-stamp-on-nlc-images

User supplies lat,lon,elev, and camera time offset to UT, the script retrieves the solar altitude from JPL that matches the UT time of the image, then puts a stamp on a copy of the image (resized if you want). Loops through the whole folder (assumes they are from the same session). Also outputs text only. 

As much as it was designed to run on windows, it will work on linux with minor modification of the directory (\ instead of /) parameters.

Requirements:

- ImageMagick (free)

- ActiveState Perl (free) on Windows with a free Komodo editor

- Internet [to access JPL's Horizons ephemeris service]
Regards,and best wishes for a great 2018 NLC season!
Alister.

[johnm]

I set my NLC camera to UTC. Then use EXIFTool to set the filename to the date and time the image was taken. It is generally easier to use the GUI but this particular operation requires that you use the command line. The GUI has a facility to use command lines from it.

The command line I use is Exif:DocumentName<$filename -r -d %Y%m%d-%H%M%S-%%c.%%e "-FileName<DateTimeOriginal"

This gets over the problem of the file dates and times changing when they are copied from the camera to my RaspberryPi controller and then to my NAS.

EXIFTool can also be used to write/'read  information user created EXIF tags so the Solar Declination could be stored in a user tag. Also there are facilities to store the location from a GPS in the EXIF location tags. A very powerful tool however it does not do image overlays.

John Murrell