Processes RINEX navigation files.
Calculates satellite positions using broadcast ephemeris.
Plots satellite tracks in azimuth-elevation coordinates.
Customizable observer location.
Color-codes satellites by constellation (GPS, Galileo, GLONASS, BeiDou).
Elevation mask set to 5°, configurable via the --elev-mask optional argument.
Outputs high-quality image in PDF format. EPS, PNG, and SVG formats are also available via the --format optional argument.
Non-interactive mode for CI jobs with the --no-show optional argument.
Constellations to plot can be configured via the --system optional argument.
Optionally, it uses the corresponding RINEX observation file to limit the plot to the receiver observation time via the--use-obs optional argument.
- If this argument is set, the tool looks for a matching file following standard RINEX naming conventions, and uses it if found.
- If this argument is set and the observation file is found, the position selection logic is:
  1. If user provides latitude, longitude, and altitude as positional arguments, that position is always used.
  2. Otherwise, if the provided observation file contains a valid APPROX POSITION XYZ field in its header, that position is used.
  3. Otherwise, the default position is used.

Requirements

Python 3.6+
Required packages:
- numpy
- matplotlib

Usage

Basic Command

./skyplot.py <RINEX_FILE> [LATITUDE] [LONGITUDE] [ALTITUDE]
             [--elev-mask ELEV_MASK]
             [--format {pdf,eps,png,svg}]
             [--no-show]
             [--system SYSTEM [SYSTEM ...]]
             [--use-obs]

Arguments

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
`--elev-mask`	Optional	degrees (°)	Elevation mask	5°
`--format`	Optional	-	Output {pdf,eps,png,svg}	pdf
`--no-show`	Optional	-	Do not show plot	-
`--system`	Optional	-	Systems to plot	All
`--use-obs`	Optional	-	Use RINEX obs data	-

Examples

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

Only plot GPS and Galileo satellites:

./skyplot.py brdc0010.22n -33.4592 -70.6453 520.0 --system GPS Galileo

./skyplot.py brdc0010.22n -33.4592 -70.6453 520.0 --system G E

Get a PNG file:

./skyplot.py brdc0010.22n -33.4592 -70.6453 520.0 --format png

Output

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 time if --use-obs is specified and the RINEX OBS file is found.
Color-coded by constellation.
Observer location in title.
Time range in footer.
Embedded fonts that display consistently across all systems and generate publication-ready figures.
EPS, PNG, and SVG output formats available via --format eps, --format png, and --format svg.