# Credits and licensing

Sol is developed by **Tsogtgerel Gantumur**, also credited as **Ts. Gantumur** or
**Gantumur** where space is limited. See the [licensing scope](../LICENSING.md)
and the [MIT License](../LICENSE). Individual tools include their own full license.

## Planetary models

The original English and Mongolian pages credit:

- Prof. van Gent's [Almagest Ephemeris Calculator](https://webspace.science.uu.nl/~gent0113/astro/almagestephemeris.htm).
- Prof. Duke's [Almagest Planetary Model Animations](https://people.sc.fsu.edu/~dduke/models).

These credits are retained. They are not an MIT permission grant for upstream code.
The legacy portions remain excluded from a blanket MIT declaration while permissions
and the boundary of borrowed code are unresolved. See the local
[English](../planets-en/THIRD_PARTY_NOTICES.md) and
[Mongolian](../planets-mn/THIRD_PARTY_NOTICES.md) notices.

## Doppler and Kinetic

Doppler's current author-owned implementation is offered under MIT by the author.
The old [GPL text](../doppler/LICENSES/GPL-3.0.txt) is retained with an
[explanation of its historical scope](../doppler/NOTICE.md).
Kinetic retains its MIT provenance and original 2023 copyright year.

## Rainbow angles and Stellar warmth

These tools derive from the author's older `spectrum` notebooks. Their current Sol
implementations are offered under MIT by explicit author authorization. The older
notebooks are not imported or relicensed by this change. Their mathematical models
and source references remain documented in the tool READMEs.

## Armatur and Sundial

Armatur retains its source history and dedication to M. Purev-Erdene in its
[README](../armatur/README.md#dedication) and interface. Sundial records its
geometrical references in its [README](../sundial/README.md#provenance-and-license).