Skymap Convert

A dependency-light package for skymap operations--use the LSST skymap without the LSST stack.

Made for use within lsdb-rubin; can also be used on its own.

Quick start

1. Install the package.

pip install skymap-convert

2. Import a skymap reader.

import skymap_convert

reader = skymap_convert.ConvertedSkymapReader(preset="lsst_skymap")

3. Optionally, call summarize to take a peek at the convents of the converted skymap.

reader.summarize()

# Prints:
# 
# Skymap Summary
# ----------------------------------------
# Path:               /path/to/skymap-convert/converted_skymaps/lsst_skymap
# Name:               lsst_skymap
# Generated:          2025-07-01T18:11:20.873149Z
# ...

4. Use get_tract_vertices and get_patch_vertices to access the data.
   (See Reading and using a converted skymap.ipynb for more details.)

reader.get_tract_vertices(42)

# Returns:
#
# [[86.16241626810654, -88.63764259611838],
# [92.73276185933494, -88.5876043887882],
# [90.57872844947276, -88.43062126829582],
# [84.63000467541433, -88.47549635501055]]

reader.get_patch_vertices(1234, 56)

# Returns:
#
# [[353.19436746094334, -61.733705740129906],
# [353.5462936615678, -61.73505840062234],
# [353.54818789227375, -61.568395336612376],
# [353.19815518019567, -61.567052069980534]]

5. To plot, call plot_patches.
   (See Skymap plotting methods.ipynb for more details.)

reader.plot_patches(
    [
        (60, 0),
        (61, 8)
    ],
    tract_outer_boundaries=60
)

6. Finally, clean up the reader's temp files:

reader.cleanup()

A note on dependencies

In its simplest form, Skymap Convert requires no LSST-stack dependences.

This means that users may read and use the built-in LSST skymap (or any other pre-converted skymaps) with just the core version of this package (which can be obtained via pip install skymap-convert, or cloning the repo and running pip install .).

Users who wish to convert their own skymap from the lsst.skymap RingsSkyMap type will need to install additional dependencies. These may be installed by:

git clone https://github.com/lincc-frameworks/skymap-convert.git
cd skymap-convert
pip install '.[dev]'

For more information

A general overview on skymaps and how they are structured

See Skymaps overview.

Converting your own skymaps

See Converting from LSST skymaps.ipynb.