soma

soma (Simons Observatory Map-based Analysis) is a set of companion tools for use with the pixell library.

This library is in active early development and its API will likely change significantly. It is meant to replace msyriac/orphics and integrate in modules from other libraries that supplement pixell.

Installation

To install from a local checkout, including the development dependencies:

git clone https://github.com/simonsobs/soma.git
cd soma
[uv] pip install -e ".[dev]"

A PyPI instance will be deployed once development is mature.

Usage

import somapy

print(somapy.__version__)

Runnable, pre-executed notebooks live in examples/; each is generated from a plain-Python builder script beside it.

Development

pytest              # run the test suite
ruff check .        # lint
ruff format .       # format

Documentation is built with Sphinx and hosted on Read the Docs:

[uv] pip install -e ".[docs]"
make -C docs html        # open docs/_build/html/index.html
make -C docs livehtml    # live preview with automatic rebuilds

Attribution

soma bundles one external data product: src/somapy/planck_dust_equ.fits, the sky backdrop that somapy.io.plot_footprints paints its globes with. It is a derived version of the Planck Commander thermal-dust map, rotated from Galactic to equatorial coordinates, band-limited and resampled onto a 0.5° CAR grid (see the footprints docs).

If you publish a figure made with it, please cite the source map:

Planck Collaboration X, 2016, Planck 2015 results. X. Diffuse component separation: Foreground maps, A&A 594, A10 (arXiv:1502.01588)

and include the Planck acknowledgement:

Based on observations obtained with Planck (http://www.esa.int/Planck), an ESA science mission with instruments and contributions directly funded by ESA Member States, NASA, and Canada.

The exact product is COM_CompMap_dust-commander_0256_R2.00.fits, column 0 (I_ML — dust intensity at 545 GHz in µK_RJ, HEALPix Nside 256, 60′ FWHM, PROCVER = DX11D), from the Planck Legacy Archive, also mirrored at IRSA.