Metadata-Version: 2.4
Name: TerraFrame
Version: 0.2.0
Summary: A library for calculating the orientation of the earth relative to GCRS.
Author-email: Caleb Morrison <cmorrison8191@gmail.com>
Maintainer-email: Caleb Morrison <cmorrison8191@gmail.com>
License: Mozilla Public License
        Version 2.0
        1. Definitions
        1.1. “Contributor”
        means each individual or legal entity that creates, contributes to the
        creation of, or owns Covered Software.
        
        1.2. “Contributor Version”
        means the combination of the Contributions of others (if any) used by a
        Contributor and that particular Contributor’s Contribution.
        
        1.3. “Contribution”
        means Covered Software of a particular Contributor.
        
        1.4. “Covered Software”
        means Source Code Form to which the initial Contributor has attached the
        notice in Exhibit A, the Executable Form of such Source Code Form, and
        Modifications of such Source Code Form, in each case including portions
        thereof.
        
        1.5. “Incompatible With Secondary Licenses”
        means
        
        that the initial Contributor has attached the notice described in Exhibit B
        to the Covered Software; or
        
        that the Covered Software was made available under the terms of version 1.1 or
        earlier of the License, but not also under the terms of a Secondary License.
        
        1.6. “Executable Form”
        means any form of the work other than Source Code Form.
        
        1.7. “Larger Work”
        means a work that combines Covered Software with other material, in a separate
        file or files, that is not Covered Software.
        
        1.8. “License”
        means this document.
        
        1.9. “Licensable”
        means having the right to grant, to the maximum extent possible, whether at
        the time of the initial grant or subsequently, any and all of the rights
        conveyed by this License.
        
        1.10. “Modifications”
        means any of the following:
        
        any file in Source Code Form that results from an addition to, deletion from,
        or modification of the contents of Covered Software; or
        
        any new file in Source Code Form that contains any Covered Software.
        
        1.11. “Patent Claims” of a Contributor
        means any patent claim(s), including without limitation, method, process, and
        apparatus claims, in any patent Licensable by such Contributor that would be
        infringed, but for the grant of the License, by the making, using, selling,
        offering for sale, having made, import, or transfer of either its
        Contributions or its Contributor Version.
        
        1.12. “Secondary License”
        means either the GNU General Public License, Version 2.0, the GNU Lesser
        eneral Public License, Version 2.1, the GNU Affero General Public License,
        Version 3.0, or any later versions of those licenses.
        
        1.13. “Source Code Form”
        means the form of the work preferred for making modifications.
        
        1.14. “You” (or “Your”)
        means an individual or a legal entity exercising rights under this License.
        For legal entities, “You” includes any entity that controls, is controlled by,
        or is under common control with You. For purposes of this definition,
        “control” means (a) the power, direct or indirect, to cause the direction or
        management of such entity, whether by contract or otherwise, or (b) ownership
        of more than fifty percent (50%) of the outstanding shares or beneficial
        ownership of such entity.
        
        2. License Grants and Conditions
        2.1. Grants
        Each Contributor hereby grants You a world-wide, royalty-free, non-exclusive
        license:
        
        under intellectual property rights (other than patent or trademark) Licensable
        by such Contributor to use, reproduce, make available, modify, display,
        perform, distribute, and otherwise exploit its Contributions, either on an
        unmodified basis, with Modifications, or as part of a Larger Work; and
        
        under Patent Claims of such Contributor to make, use, sell, offer for sale,
        have made, import, and otherwise transfer either its Contributions or its
        Contributor Version.
        
        2.2. Effective Date
        The licenses granted in Section 2.1 with respect to any Contribution become
        effective for each Contribution on the date the Contributor first distributes
        such Contribution.
        
        2.3. Limitations on Grant Scope
        The licenses granted in this Section 2 are the only rights granted under this
        License. No additional rights or licenses will be implied from the
        distribution or licensing of Covered Software under this License.
        Notwithstanding Section 2.1(b) above, no patent license is granted by a
        Contributor:
        
        for any code that a Contributor has removed from Covered Software; or
        
        for infringements caused by: (i) Your and any other third party’s
        modifications of Covered Software, or (ii) the combination of its
        Contributions with other software (except as part of its Contributor Version);
        or
        
        under Patent Claims infringed by Covered Software in the absence of its
        Contributions.
        
        This License does not grant any rights in the trademarks, service marks, or
        logos of any Contributor (except as may be necessary to comply with the notice
        requirements in Section 3.4).
        
        2.4. Subsequent Licenses
        No Contributor makes additional grants as a result of Your choice to
        distribute the Covered Software under a subsequent version of this License
        (see Section 10.2) or under the terms of a Secondary License (if permitted
        under the terms of Section 3.3).
        
        2.5. Representation
        Each Contributor represents that the Contributor believes its Contributions
        are its original creation(s) or it has sufficient rights to grant the rights
        to its Contributions conveyed by this License.
        
        2.6. Fair Use
        This License is not intended to limit any rights You have under applicable
        copyright doctrines of fair use, fair dealing, or other equivalents.
        
        2.7. Conditions
        Sections 3.1, 3.2, 3.3, and 3.4 are conditions of the licenses granted in
        Section 2.1.
        
        3. Responsibilities
        3.1. Distribution of Source Form
        All distribution of Covered Software in Source Code Form, including any
        Modifications that You create or to which You contribute, must be under the
        terms of this License. You must inform recipients that the Source Code Form
        of the Covered Software is governed by the terms of this License, and how they
        can obtain a copy of this License. You may not attempt to alter or restrict
        the recipients’ rights in the Source Code Form.
        
        3.2. Distribution of Executable Form
        If You distribute Covered Software in Executable Form then:
        
        such Covered Software must also be made available in Source Code Form, as
        described in Section 3.1, and You must inform recipients of the Executable
        Form how they can obtain a copy of such Source Code Form by reasonable means
        in a timely manner, at a charge no more than the cost of distribution to the
        recipient; and
        
        You may distribute such Executable Form under the terms of this License, or
        sublicense it under different terms, provided that the license for the
        Executable Form does not attempt to limit or alter the recipients’ rights in
        the Source Code Form under this License.
        
        3.3. Distribution of a Larger Work
        You may create and distribute a Larger Work under terms of Your choice,
        provided that You also comply with the requirements of this License for the
        Covered Software. If the Larger Work is a combination of Covered Software with
        a work governed by one or more Secondary Licenses, and the Covered Software is
        not Incompatible With Secondary Licenses, this License permits You to
        additionally distribute such Covered Software under the terms of such
        Secondary License(s), so that the recipient of the Larger Work may, at
        their option, further distribute the Covered Software under the terms of
        either this License or such Secondary License(s).
        
        3.4. Notices
        You may not remove or alter the substance of any license notices (including
        copyright notices, patent notices, disclaimers of warranty, or limitations of
        liability) contained within the Source Code Form of the Covered Software,
        except that You may alter any license notices to the extent required to remedy
        known factual inaccuracies.
        
        3.5. Application of Additional Terms
        You may choose to offer, and to charge a fee for, warranty, support, indemnity
        or liability obligations to one or more recipients of Covered Software.
        However, You may do so only on Your own behalf, and not on behalf of any
        Contributor. You must make it absolutely clear that any such warranty,
        support, indemnity, or liability obligation is offered by You alone, and You
        hereby agree to indemnify every Contributor for any liability incurred by such
        Contributor as a result of warranty, support, indemnity or liability terms You
        offer. You may include additional disclaimers of warranty and limitations of
        liability specific to any jurisdiction.
        
        4. Inability to Comply Due to Statute or Regulation
        If it is impossible for You to comply with any of the terms of this License
        with respect to some or all of the Covered Software due to statute, judicial
        order, or regulation then You must: (a) comply with the terms of this License
        to the maximum extent possible; and (b) describe the limitations and the code
        they affect. Such description must be placed in a text file included with all
        distributions of the Covered Software under this License. Except to the extent
        prohibited by statute or regulation, such description must be sufficiently
        detailed for a recipient of ordinary skill to be able to understand it.
        
        5. Termination
        5.1. The rights granted under this License will terminate automatically if You
        fail to comply with any of its terms. However, if You become compliant, then
        the rights granted under this License from a particular Contributor are
        reinstated (a) provisionally, unless and until such Contributor explicitly and
        finally terminates Your grants, and (b) on an ongoing basis, if such
        Contributor fails to notify You of the non-compliance by some reasonable
        means prior to 60 days after You have come back into compliance. Moreover,
        Your grants from a particular Contributor are reinstated on an ongoing basis
        if such Contributor notifies You of the non-compliance by some reasonable
        means, this is the first time You have received notice of non-compliance with
        this License from such Contributor, and You become compliant prior to 30 days
        after Your receipt of the notice.
        
        5.2. If You initiate litigation against any entity by asserting a patent
        infringement claim (excluding declaratory judgment actions, counter-claims,
        and cross-claims) alleging that a Contributor Version directly or indirectly
        infringes any patent, then the rights granted to You by any and all
        Contributors for the Covered Software under Section 2.1 of this License
        shall terminate.
        
        5.3. In the event of termination under Sections 5.1 or 5.2 above, all end user
        license agreements (excluding distributors and resellers) which have been
        validly granted by You or Your distributors under this License prior to
        termination shall survive termination.
        
        6. Disclaimer of Warranty
        Covered Software is provided under this License on an “as is” basis, without
        warranty of any kind, either expressed, implied, or statutory, including,
        without limitation, warranties that the Covered Software is free of defects,
        merchantable, fit for a particular purpose or non-infringing. The entire risk
        as to the quality and performance of the Covered Software is with You. Should
        any Covered Software prove defective in any respect, You (not any Contributor)
        assume the cost of any necessary servicing, repair, or correction. This
        disclaimer of warranty constitutes an essential part of this License. No use
        of any Covered Software is authorized under this License except under this
        disclaimer.
        
        7. Limitation of Liability
        Under no circumstances and under no legal theory, whether tort (including
        negligence), contract, or otherwise, shall any Contributor, or anyone who
        distributes Covered Software as permitted above, be liable to You for any
        direct, indirect, special, incidental, or consequential damages of any
        character including, without limitation, damages for lost profits, loss of
        goodwill, work stoppage, computer failure or malfunction, or any and all other
        commercial damages or losses, even if such party shall have been informed of
        the possibility of such damages. This limitation of liability shall not apply
        to liability for death or personal injury resulting from such party’s
        negligence to the extent applicable law prohibits such limitation. Some
        jurisdictions do not allow the exclusion or limitation of incidental or
        consequential damages, so this exclusion and limitation may not apply to You.
        
        8. Litigation
        Any litigation relating to this License may be brought only in the courts of
        a jurisdiction where the defendant maintains its principal place of business
        and such litigation shall be governed by laws of that jurisdiction, without
        reference to its conflict-of-law provisions. Nothing in this Section shall
        prevent a party’s ability to bring cross-claims or counter-claims.
        
        9. Miscellaneous
        This License represents the complete agreement concerning the subject matter
        hereof. If any provision of this License is held to be unenforceable, such
        provision shall be reformed only to the extent necessary to make it
        enforceable. Any law or regulation which provides that the language of a
        contract shall be construed against the drafter shall not be used to
        construe this License against a Contributor.
        
        10. Versions of the License
        10.1. New Versions
        Mozilla Foundation is the license steward. Except as provided in Section 10.3,
        no one other than the license steward has the right to modify or publish new
        versions of this License. Each version will be given a distinguishing version
        number.
        
        10.2. Effect of New Versions
        You may distribute the Covered Software under the terms of the version of the
        License under which You originally received the Covered Software, or under the
        terms of any subsequent version published by the license steward.
        
        10.3. Modified Versions
        If you create software not governed by this License, and you want to create a
        new license for such software, you may create and use a modified version of
        this License if you rename the license and remove any references to the name
        of the license steward (except to note that such modified license differs from
        this License).
        
        10.4. Distributing Source Code Form that is Incompatible With Secondary
        Licenses
        If You choose to distribute Source Code Form that is Incompatible With
        Secondary Licenses under the terms of this version of the License, the
        notice described in Exhibit B of this License must be attached.
        
        Exhibit A - Source Code Form License Notice
        This Source Code Form is subject to the terms of the Mozilla Public License,
        v. 2.0. If a copy of the MPL was not distributed with this file, You can
        obtain one at https://mozilla.org/MPL/2.0/.
        
        If it is not possible or desirable to put the notice in a particular file,
        then You may include the notice in a location (such as a LICENSE file in a
        relevant directory) where a recipient would be likely to look for such a
        notice.
        
        You may add additional accurate notices of copyright ownership.
        
        Exhibit B - “Incompatible With Secondary Licenses” Notice
        This Source Code Form is “Incompatible With Secondary Licenses”, as defined by
        the Mozilla Public License, v. 2.0.
Project-URL: Source, https://github.com/cmorrison31/TerraFrame
Keywords: IAU,Precession,Nutation,Earth,Astronomy,IERS,Transformation,ITRS,GCRS
Classifier: Development Status :: 4 - Beta
Classifier: Intended Audience :: Science/Research
Classifier: Topic :: Scientific/Engineering :: Astronomy
Classifier: License :: OSI Approved :: Mozilla Public License 2.0 (MPL 2.0)
Classifier: Programming Language :: Python :: 3
Classifier: Programming Language :: Python :: 3.12
Classifier: Programming Language :: Python :: 3.13
Classifier: Programming Language :: Python :: 3 :: Only
Requires-Python: >=3.12
Description-Content-Type: text/markdown
License-File: LICENSE.txt
Requires-Dist: numpy
Requires-Dist: platformdirs
Requires-Dist: requests
Provides-Extra: animation
Requires-Dist: manim; extra == "animation"
Provides-Extra: test
Requires-Dist: pytest; extra == "test"
Requires-Dist: pyerfa; extra == "test"
Requires-Dist: astropy; extra == "test"
Dynamic: license-file

[![Test](https://github.com/cmorrison31/TerraFrame/actions/workflows/test.yml/badge.svg)](https://github.com/cmorrison31/TerraFrame/actions/workflows/test.yml)
[![Release](https://github.com/cmorrison31/TerraFrame/actions/workflows/release.yml/badge.svg)](https://github.com/cmorrison31/TerraFrame/actions/workflows/release.yml)

# TerraFrame
TerraFrame is a library designed to provided key Earth related calculations and 
associated functionality to modeling & simulation software. Primarily, 
TerraFrame provides Earth orientation and gravity routines.

![Animation of CGRS to ITRS Transformation](https://raw.githubusercontent.com/cmorrison31/TerraFrame/main/Animations%20and%20Plots/GCRS_to_ITRS.gif)

![Example of Precession, Nutation, & Polar Motion](https://raw.githubusercontent.com/cmorrison31/TerraFrame/main/Animations%20and%20Plots/Earth%20Motion%20Example.gif)

## Earth Orientation
TerraFrame provides an implementation of the IAU 2006/2000A precession-nutation 
model which accounts for precession, nutation, and polar motion. Specifically, 
this implementation provides a transformation tensor between the Geocentric 
Celestial Reference System (GCRS) and the International Terrestrial Reference 
System (ITRS).

TerraFrame also provides routines for calculating the Earth's angular 
velocity tensor. The angular velocity tensor is based on the partial 
derivative of the numerous IAU 2006/2000A equations with respect to time (in 
seconds).

IERS precession and nutation model data files are shipped with TerraFrame. 
Utility code is also provided which automates the downloading of IERS data for 
polar motion, UTC, and UT1 offsets.

## Gravity
Gravity calculations are provided by an implementation of the EGM2008. A double 
Clenshaw summation approach is used to evaluate the spherical harmonics which 
yields high numerical stability and computational efficiency. TerraFrame is 
numerically capable of evaluating EGM2008 to it’s complete degree and 
order: 2190.

By default, only data for degree and order 200 is shipped with TerraFrame for 
space efficiency. Most near earth modeling & simulation applications will not 
need to exceed degree and order 100 per WGS84 guidance.

## Ancillary Functionality
Support is provided for converting from geodetic latitude, longitude, and 
height above ellipsoid to geocentric cartesian coordinates or vice versa. The 
WGS84 spheroid and a simple spherical earth are provided as built-in options.

TerraFrame also provides robust datetime and timescale conversion functionality 
that is fully leap second aware. Conversions between UTC, UT1, TT, and TAI are 
provided. The user is encouraged to not work in UTC directly to avoid leap 
second ambiguity. Conversion to UTC from TT or TAI can be safely done in 
post-processing.

# License

This project - except for the IERS and WGS84 data files - is covered under the 
Mozilla Public License Version 2.0 (MPL2). See the LICENSE.txt file for more
information.

# Acknowledgements and References

This project uses data published by the International Earth Rotation and
Reference Systems Service (IERS). The original data along with additional
information can be found on the IERS website:
[here.](https://www.iers.org/IERS/EN/DataProducts/EarthOrientationData/eop.html)

The [Astropy](https://www.astropy.org/),
[PyERFA](https://pypi.org/project/pyerfa/), and 
[GeographicLib](https://geographiclib.sourceforge.io/index.html) libraries have 
been used as invaluable sources of truth for the testing of TerraFrame.

This project would not have been possible without the technical information
provided by the following sources:

- Urban, S. E., & Seidelmann, P. K. (Eds.). Explanatory Supplement to the
  Astronomical Almanac (3rd ed.). University Science Books, 2013. ISBN:
  978-1-891389-85-6.
- Gérard Petit and Brian Luzum (Eds.). IERS Conventions (2010), IERS Technical
  Note No. 36, Frankfurt am Main: Verlag des Bundesamts für Kartographie und
  Geodäsie, 2010. ISBN: 3-89888-989-6.
- Deakin, R.E., 1998, 'Derivatives of the earth’s potentials'. Geomatics 
  Research Australasia, No.68, June, 1998, pp. 31-60.

# Acronyms and Abbreviations

| Term | Meaning                                                    |
|------|------------------------------------------------------------|
| CIO  | Celestial Intermediate Origin                              |
| CIP  | Celestial Intermediate Pole                                |
| CIRS | Celestial Intermediate Reference System                    |
| CEO  | Celestial Ephemeris Origin                                 |
| EGM  | Earth Gravitational Model                                  |  
| GCRS | Geocentric Celestial Reference System                      |
| IAU  | International Astronomical Union                           |
| IERS | International Earth Rotation and Reference Systems Service |
| ITRF | International Terrestrial Reference Frame                  |
| ITRS | International Terrestrial Reference System                 |
| TAI  | International Atomic Time                                  |
| TIO  | Terrestrial Intermediate Origin                            |
| TIRS | Terrestrial Intermediate Reference System                  |
| TT   | Terrestrial Time                                           |
| UT1  | Universal Time                                             |
| UTC  | Coordinated Universal Time                                 |
| WGS  | World Geodetic System                                      |


