Processes RINEX navigation files.
Optionally uses an OBS file to limit plot to the receiver observation time (--use-obs).
- When enabled, the tool looks for a matching file by replacing the last character of the NAV filename with O/o and uses it if found.
Calculates satellite positions using broadcast ephemeris.
Plots satellite tracks in azimuth-elevation coordinates.
Color-codes satellites by constellation (GPS, Galileo, GLONASS, BeiDou).
Customizable observer location.
Outputs high-quality image in PDF format.
Non-interactive mode for CI jobs (with --no-show flag).

Requirements

Usage

./skyplot.py <RINEX_FILE> [LATITUDE] [LONGITUDE] [ALTITUDE] [--use-obs] [--no-show]

Argument	Type	Units	Description	Default
`RINEX_NAV_FILE`	Required	-	RINEX nav file path	-
`LATITUDE`	Optional	degrees (°)	North/South position	41.275°N
`LONGITUDE`	Optional	degrees (°)	East/West position	1.9876°E
`ALTITUDE`	Optional	meters (m)	Height above sea level	80.0 m
`--use-obs`	Optional	-	Use RINEX obs data	-
`--no-show`	Optional	-	Do not show plot	-

Skyplot from default location (Castelldefels, Spain):
```
./skyplot.py brdc0010.22n
```
Skyplot from custom location (New York City, USA):
```
./skyplot.py brdc0010.22n 40.7128 -74.0060 10.0
```
Skyplot from custom location (Santiago, Chile) using receiver observation time:
```
./skyplot.py brdc0010.22n -33.4592 -70.6453 520.0 --use-obs
```

Non-interactive mode (for CI jobs):

./skyplot.py brdc0010.22n -33.4592 -70.6453 520.0 --no-show

The script generates a PDF file named skyplot_<RINEX_FILE>.pdf (with dots in <RINEX_FILE> replaced by _) with:

Satellite trajectories over all epochs in the file.
- NAV file - ephemeris time range (default)
- Receiver observation if --use-obs is specified and OBS file is found
Color-coded by constellation.
Observer location in title.
Time range in footer.