PySQM info
PySQM is a multi-platform, open-source software designed to read and plot data from Unihedron SQM-LE and SQM-LU photometers, giving as an output files with the International Dark Sky Association (IDA) NSBM Community Standards for Reporting Skyglow Observations.
PySQM known issues
In headless systems, such as the Raspberry PI, if you run the program without X, you may suffer from the following fatal error when the program tries to generate the plot:
This application failed to start because it could not find or load the Qt platform plugin “xcb”.
Available platform plugins are: eglfs, kms, linuxfb, minimal, minimalegl, offscreen, xcb.
Reinstalling the application may fix this problem. Aborted (core dumped)
In order to avoid this problem, you need to create (or modify if the file exists) in your HOME directory the following file:
.config/matplotlib/
You just need to set the matplotlib backend to Agg:
backend : Agg
Save the changes and exit. Now, PySQM should make the plots without issues. You may need to restart PySQM to apply the changes.
References:
http://awhan.wordpress.com/
http://matplotlib.org/users/
"PySQM the UCM open source software to read, plot and store data from SQM photometers"
Nievas Rosillo, Mireia and Zamorano Calvo, Jaime (2014) UCM eprint (PDF)