# Third-party notices ## IAU Minor Planet Center comet elements The offline comet catalogue is generated from an IAU Minor Planet Center `CometEls.txt` snapshot using the MPC Ephemerides and Orbital Elements comet format. - Project: https://www.minorplanetcenter.net/ - Format documentation: https://docs.minorplanetcenter.net/mpc-ops-docs/orbits/comet-orbit-format/ - Pinned source SHA-256: `8e7bb528fac5c5e8f0f11c72f4fa1102ee50220bab8654a4fedba1a558e68a8f` - Records: 1,214 Celestia Atlas changes include fixed-column parsing, compact JSON/JavaScript conversion, two-body universal-variable propagation, light-time correction, observer parallax, search metadata and approximate magnitude calculation. ## Astronomy Engine Solar-system positions, illumination and visual magnitudes are calculated with **Astronomy Engine** by Donald Cross. - Project: https://github.com/cosinekitty/astronomy - Version pinned by this project: `2.1.19` - Licence: MIT Astronomy Engine is distributed under the MIT licence. Its copyright and permission notice are available in the upstream project. ## HYG v4.1 naked-eye star layer The separate star supplement is derived from the **HYG Database** by David Nash (Astronomy Nexus). - Project: https://github.com/astronexus/HYG-Database - Pinned version: `v4.1` - Pinned source commit: `3bf37f4b2d5460e1278286320d1d62fab9b493c1` - Pinned source: https://github.com/astronexus/HYG-Database/blob/3bf37f4b2d5460e1278286320d1d62fab9b493c1/hyg/CURRENT/hygdata_v41.csv - Source SHA-256: `d9f69fd86bbf90a4e4d52b4c5c53eacfa6dfc0bfdef85bfd94f095e0bebe4ebd` - Upstream rows: 119,626 - Licence: Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0) - Local licence notice: `licenses/HYG-CC-BY-SA-4.0.md` Celestia Atlas selects the 8,920 non-solar records whose apparent visual magnitude is at most 6.5. To prevent duplicate plotting, it removes all 140 HYG components within 2 arcminutes of a star in the curated 130-record `STAR_DATA` layer. The 8,780 remaining records retain their HYG row identity, HIP identifier when supplied, HYG proper name when supplied, J2000.0 right ascension and declination, visual magnitude, optional B-V colour index, constellation and a compact HYG source label. The `named` field is emitted only for rows with a HYG proper name. HYG's `ci` field is renamed to `bv`; no missing colour is invented. These derived assets remain under CC BY-SA 4.0 and are kept separate from the MIT code and the other generated catalogue layers: ```text hyg-star-catalog.js data/hyg-star-catalog.json ``` Redistributors must retain the attribution, source link, licence link and indication of the selection, field renaming, duplicate removal and compact serialization modifications described above. ## SIMBAD A66 planetary-nebula layer The separate Abell 1966 planetary-nebula layer is derived from a pinned TAP response from the **SIMBAD astronomical database**, operated at CDS, Strasbourg, France. - Service: https://simbad.u-strasbg.fr/simbad/ - TAP endpoint: https://simbad.u-strasbg.fr/simbad/sim-tap/sync - Advertised service release at retrieval: `SIMBAD4 1.8 - 2026-06` - Retrieval date: `2026-07-15` - Committed query: `data/sources/simbad/a66-2026-07-15.adql` - Query SHA-256: `ab2fe86d5c84e6d027bcb363c9d775b428d11eb003ec3fbf426331b64751e639` - Committed TAP response: `data/sources/simbad/a66-2026-07-15.tsv` - Response SHA-256: `1aac0fb91c4ae39581b86a6bf1e8cc2fbdeaa93d0460762f73df59dd7e501348` - Response rows: 1,152 exact identifiers for 86 distinct `PN A66` objects - Licence: Open Data Commons Open Database License 1.0 (`ODbL-1.0`) - Local licence notice: `licenses/SIMBAD-ODbL-1.0.md` Required acknowledgement retained by Celestia Atlas: > This research has made use of the SIMBAD database, operated at CDS, > Strasbourg, France. SIMBAD also requests citation of Wenger et al. (2000), “The SIMBAD astronomical database,” _Astronomy and Astrophysics Supplement Series_ 143, 9. The historical designation originates with Abell (1966), _Astrophysical Journal_ 144, 259. Celestia Atlas groups the long-form response by the SIMBAD object selected by the query, normalizes display spacing, adds deterministic `Abell`, `A66`, and `PN A66` search variants, and preserves the SIMBAD main identifier, object type, ICRS coordinates, and exact cross-identifiers. Only four unique exact NGC/IC identities are emitted as optional merge keys. Sky position is never used to infer identity. SIMBAD's current classification is preserved even for historical A66 entries now typed as a galaxy, possible object, possible active galaxy, emission-line galaxy, H II region, or supernova remnant rather than a planetary nebula. The snapshot and these derived assets remain under ODbL 1.0 and are kept separate from the MIT code and other catalogue licence boundaries: ```text data/sources/simbad/a66-2026-07-15.tsv abell-pn-catalog.js data/abell-pn-catalog.json ``` Redistributors must retain the ODbL terms, SIMBAD attribution, source/query metadata, hashes, and modification statement above. ### SIMBAD Messier 40 completion The normalized base catalogue also includes one separately sourced SIMBAD record for `M40` / Winnecke 4, retrieved on `2026-07-22`: - Record: https://simbad.harvard.edu/simbad/sim-basic?Ident=M40 - Retained data: identifier and ICRS position - Licence: Open Data Commons Open Database License 1.0 (`ODbL-1.0`) - Local licence notice: `licenses/SIMBAD-ODbL-1.0.md` Celestia Atlas converts the published sexagesimal position to decimal degrees and represents M40 as a point-like double-star marker. It does not infer a deep-sky object class or angular extent. The SIMBAD acknowledgement above also applies to this record. The explicit OpenNGC-only package exports do not contain this addition. ## OpenNGC The generated deep-sky catalogue is based on **OpenNGC**, created by Mattia Verga and contributors. - Project: https://github.com/mattiaverga/OpenNGC - Data licence: Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0) - Version pinned by this project: `v20260501` OpenNGC incorporates data from sources including the NASA/IPAC Extragalactic Database (NED), HyperLEDA, SIMBAD, HEASARC, and Harold Corwin's NGC/IC research. See the OpenNGC project and each generated record's source information for the upstream acknowledgements. Changes made by Celestia Atlas include CSV parsing, filtering out star, duplicate and explicitly non-existent entries from the plotted DSO set, normalising identifiers, compact JSON/JavaScript conversion, and merging a small curated description layer for prominent objects. The normalized base catalogue assigns Messier membership from OpenNGC cross-identifiers and follows NASA Hubble's documented convention of identifying M102 with NGC 5866 (the Spindle Galaxy): https://science.nasa.gov/mission/hubble/science/explore-the-night-sky/hubble-messier-catalog/messier-102/. The historical M102 identification remains disputed; this association is explicitly recorded as a convention rather than presented as settled fact. Generated OpenNGC-derived catalogue files must remain available under CC BY-SA 4.0 with attribution and share-alike terms. ## Western constellation line paths The image-free Western constellation overlay is derived from Stellarium's Western sky culture. Celestia Atlas retains the 88 IAU line paths and Latin names, removes illustrations, image anchors, boundaries, translations and Stellarium runtime fields, and resolves the 691 referenced HIP vertices to ICRS/J2000 coordinates using the pinned HYG v4.1 snapshot. The resulting 674 segments are distributed separately as `data/western-constellations.json` and `western-constellations.js` under GPL-2.0-or-later. The imported source snapshot SHA-256 is `d206983eee84a73279324845c1e7a5b114317a59042f8bc3af83b18651c6e065`. No sky-culture illustration is included. Redistribution must retain this notice, the attribution, modification statement and `licenses/Stellarium-GPL-2.0.txt`. ## Stellarium DSO cross-index supplement The separate public historical DSO supplement is derived from the standard DSO catalogue distributed with **Stellarium**. - Project: https://github.com/Stellarium/stellarium - Pinned Stellarium version: `v26.2` - DSO catalogue version: `3.23` - Pinned source: https://raw.githubusercontent.com/Stellarium/stellarium/v26.2/nebulae/default/catalog.txt - Validated upstream rows: 94,899 - Upstream licence: GPL-2.0-or-later (declared by Stellarium's `CITATION.cff`) - Full licence copy: `licenses/Stellarium-GPL-2.0.txt` Celestia Atlas selects 8,658 rows carrying at least one non-zero Abell/ACO, Barnard, Sh2, vdB, RCW, LDN, or LBN cross-index. Modifications include strict schema and row count validation; source-aware aliases; FK5/J2000-to-ICRS transformation with build-time coordinate provenance; conservative type mapping; dark-nebula opacity handling that does not mislabel the ordinal class as magnitude; exact axis/position-angle preservation when present; provenance metadata; and deterministic compact JSON/JavaScript serialization. Original Stellarium type, morphology when supplied, row identifier, selected cross-indices, catalogue version, and source URL are retained in the derived records or supplement metadata. The Abell/ACO galaxy-cluster designations refer to Abell, Corwin, and Olowin (1989), “A Catalog of Rich Clusters of Galaxies,” _Astrophysical Journal Supplement Series_ 70, 1, DOI `10.1086/191333`. They are distinct from the Abell-1966 planetary-nebula designations in the separate SIMBAD A66 layer. The following derived assets remain under GPL-2.0-or-later and are kept separate from the OpenNGC-derived CC BY-SA 4.0 files: ```text stellarium-supplement.js data/stellarium-dso-supplement.json data/stellarium-supplement-meta.json ``` Redistribution of the supplement must comply with GPL-2.0-or-later, including the applicable notice, licence-copy, and corresponding-source requirements. Its inclusion does not relicense Celestia Atlas's MIT source code or OpenNGC's CC BY-SA 4.0 catalogue data. ## Optional historical nebula and dark-cloud catalogues Celestia Atlas contains build-time import support for the following CDS/VizieR catalogues. These provide richer source-specific properties than the public Stellarium cross-index supplement, but are not its data source. Their complete source tables and transformed records are **not** committed or included in the public deployment because neither the current CDS catalogue metadata nor the catalogue ReadMes state an open redistribution licence. | Catalogue | Original publication | CDS/VizieR ID | | --------------------------------------- | -------------------------------------------------------------------------------------------------------- | ------------- | | Lynds Dark Nebulae (LDN) | Lynds, B. T. (1962), _ApJS_ 7, 1, DOI `10.1086/190072` | `VII/7A` | | Barnard dark objects | Barnard, E. E. (1927), _A Photographic Atlas of Selected Regions of the Milky Way_ | `VII/220A` | | Lynds Bright Nebulae (LBN) | Lynds, B. T. (1965), _ApJS_ 12, 163, DOI `10.1086/190123` | `VII/9` | | Sharpless 2 H II regions | Sharpless, S. (1959), _ApJS_ 4, 257, DOI `10.1086/190049` | `VII/20` | | van den Bergh reflection nebulae | van den Bergh, S. (1966), _AJ_ 71, 990, DOI `10.1086/109995` | `VII/21` | | RCW emission nebulae | Rodgers, A. W.; Campbell, C. T.; Whiteoak, J. B. (1960), _MNRAS_ 121, 103, DOI `10.1093/mnras/121.1.103` | `VII/216` | | Southern Dark Clouds | Hartley et al. (1986), _A&AS_ 63, 27 | `VII/191` | | Feitzinger-Stuewe southern dark nebulae | Feitzinger, J. V.; Stuewe, J. A. (1984), _A&AS_ 58, 365; erratum _A&AS_ 63, 203 | `VII/68A` | CDS states in its [VizieR rules of usage](https://cds.unistra.fr/vizier-org/licences_vizier.html) that data are freely usable in a scientific context with citation of the original authors, publication, and publisher; commercial conditions depend on data origin and users must review the relevant ReadMe and journal policy. Those rules do not provide an open-source redistribution grant. The local fetch tool therefore requires an explicit acknowledgement, stores downloads under the ignored `.cache/` directory, and never runs in the public Pages workflow. A user's acknowledgement does not create redistribution rights. The source review is catalogue-specific: - `VII/7A`, `VII/9`, `VII/20`, and `VII/21` originate in historical AAS journal publications; neither their CDS records nor ReadMes identify an open data licence for the electronic tables. - Barnard's 1927 publication may be public domain in some jurisdictions, but the later machine-readable compilation served as `VII/220A` has no explicit redistribution licence. The project does not infer one. - The `VII/216` ReadMe expressly describes the original RCW/MNRAS publication as copyrighted. Local access is not treated as permission to republish it. - `VII/191` and `VII/68A` originate in A&AS/ESO publications and have no open table licence in their current CDS records. The Feitzinger-Stuewe raster is excluded entirely. When locally importing these catalogues, cite the original publication above, the specific CDS/VizieR identifier, and the CDS/VizieR service DOI `10.26093/cds/vizier`. Generated provenance records identify the source table, original identifier and coordinate frame. Celestia Atlas modifications include schema validation, identifier and alias normalization, Astropy FK4/Galactic to ICRS transformation, explicitly marked approximate size derivation, conservative cross-identification merging, and compact browser serialization. The `VII/68A` raster sky map and globule table are not part of the initial import. Do not redistribute a locally generated combined catalogue until the rights for every included source are cleared for the intended use. The public Stellarium supplement covers Abell/ACO, LDN, Barnard, LBN, Sharpless 2, vdB, and RCW cross-indices. Southern Dark Clouds (`VII/191`) and Feitzinger-Stuewe (`VII/68A`) remain local-only and are not present in the public deployment. ## NASA Image and Video Library Images downloaded with `tools/fetch_nasa_dso_images.py` come from the NASA Image and Video Library. Each image has a sidecar JSON file containing its source URL, NASA identifier, credit and a rights reminder. NASA media is generally available for informational and educational use under NASA's media usage guidelines, but NASA pages may include third-party material. Review each source page before redistribution. ## Bundled Milky Way panorama `assets/milky-way.webp` is a locally generated artistic panorama included with this project. It is not calibrated scientific survey imagery. ## Optional Digitized Sky Survey imagery The narrow-field photographic background uses the registered HiPS survey `CDS/P/DSS2/color` through this CDS-listed MAST mirror: `https://stpubdata.s3.us-east-1.amazonaws.com/mast/skybackgrounds/DSSColor` The remote survey is not bundled with, derived into, or redistributed as part of this repository. The application requests only visible tiles and may retain a bounded browser cache of tiles already viewed. A full mirror or bulk download is explicitly outside the application design. Display credit: > Digitized Sky Survey — STScI/NASA; colored and HiPS-processed by CDS > (CNRS/Unistra). The [CDS survey record](https://alasky.cds.unistra.fr/MocServer/query?ID=CDS%2FP%2FDSS2%2Fcolor&fmt=html&get=record) advertises the HiPS product under ODbL 1.0. The underlying photographic survey plates retain their own rights. The current [MAST photographic-survey policy](https://outerspace.stsci.edu/spaces/MASTDATA/pages/176435492/Photographic+Sky+Surveys) allows scientific and educational website use with acknowledgment, prohibits commercial use, and requires an agreement with STScI for bulk redistribution. The older [DSS copyright notice](https://archive.stsci.edu/dss/copyright.html) also requires acknowledgment. In addition to the visible short credit, deployments should acknowledge DSS production at STScI under U.S. Government grant NAG W-2166 and the original photographic observations from the Oschin Schmidt Telescope at Palomar and the UK Schmidt Telescope. Recheck the current terms for the intended deployment; the MIT licence for Celestia Atlas code grants no rights to remote survey imagery.