Location Kernels¶

Location Kernels (.lka files) allow you to define ground stations, observatories, or other points of interest on the surface of a celestial body.

The `Location` Object¶

A location is defined by its geodetic coordinates:

latitude_deg: Geodetic latitude.
longitude_deg: Geodetic longitude (positive East).
height_km: Altitude above the reference ellipsoid.
frame: The central body frame (e.g., ITRF93 for Earth, IAU_MOON for Moon).

Terrain Masks¶

Real-world ground stations do not have a perfect 0-degree horizon. Mountains or buildings may obstruct the view. ANISE supports Terrain Masks to account for this.

A TerrainMask is a list of Azimuth/Elevation pairs. - Azimuth: The start of the mask segment. - Elevation: The minimum elevation required for visibility in that segment.

If a mask is provided, ElevationFromLocation computations will account for it, and visibility searches will use it as the "horizon" limit.

Working with `.lka` Files¶

ANISE uses a custom Dhall-based or binary format for loading locations.

Loading (Rust/Python)¶

# Python
almanac = Almanac("de440.bsp").load("dsn_stations.lka")

# Now you can reference locations by ID or Name
azel = almanac.azimuth_elevation_range_sez_from_location_name(
    orbit_state,
    "DSS-65"
)

Creating (Python)¶

You can create location files programmatically:

from anise.astro import Location, TerrainMask, FrameUid

# Define a mask
mask = [TerrainMask(0.0, 5.0), TerrainMask(180.0, 10.0)]

# Create location
dss65 = Location(
    latitude_deg=40.427,
    longitude_deg=4.250,
    height_km=0.834,
    frame=FrameUid(399, 399), # Earth
    terrain_mask=mask,
    terrain_mask_ignored=False
)

# Export
entry = LocationDhallSetEntry(dss65, id=65, alias="DSS-65")
dhallset = LocationDhallSet([entry])
dhallset.to_dataset().save_as("my_locations.lka", True)