Credits and licences
The shared sky is drawn on real catalogue data. Each source below was checked for its reuse terms before any data was taken, and each is credited as that source asks.
Stars
- ESA/Gaia/DPAC — Gaia DR3. The Gaia data are open and free to use, provided credit is given to “ESA/Gaia/DPAC”.
- Yale Bright Star Catalogue (public domain, Harvard/Yale) — the stars brighter than V=3.0.
Named deep-sky objects
The 202-object overlay (deepsky.json) combines three sources.
- NASA/GSFC HEASARC — the
messiertable, via the HEASARC Open Archive. Acknowledged as HEASARC requests. - SIMBAD, operated at CDS, Strasbourg, France — coordinates and galaxy dimensions, used under the ODbL licence stated on the SIMBAD home page.
- OpenNGC by Mattia Verga and contributors —
github.com/mattiaverga/OpenNGC,
pinned to commit
da90466031b0372c896588b85be6016c617e205b, released under CC BY-SA 4.0.
Because OpenNGC is share-alike, the adapted file is too:
deepsky.json is redistributed under
CC BY-SA 4.0.
Changes made to the OpenNGC data: 92 named non-Messier rows were selected,
coordinates rounded to millidegrees, type and subtype normalized to a broad
galaxy / nebula / cluster / other scheme, and editorial display names supplied.
Photographs
Ten objects are drawn from ESO photographs, licensed under CC BY 4.0 per ESO’s copyright notice. ESO requires the full credit to be shown with the wording unaltered, so it is also displayed in the sky itself whenever one of these images is on screen. The images here are cropped, recentred on the catalogue position, background-removed, and scaled to 256 px.
- M 7 — ESO
- M 42 — ESO/J. Emerson/VISTA. Acknowledgment: Cambridge Astronomical Survey Unit
- NGC 253 — ESO/J. Emerson/VISTA. Acknowledgment: Cambridge Astronomical Survey Unit
- NGC 300 — ESO
- NGC 2070 — ESO/IDA/Danish 1.5 m/R. Gendler, C. C. Thöne, C. Féron, and J.-E. Ovaldsen
- NGC 3372 — ESO/APEX/T. Preibisch et al. (Submillimetre); N. Smith, University of Minnesota/NOAO/AURA/NSF (Optical)
- NGC 4755 — ESO/Y. Beletsky
- NGC 5128 — ESO
- NGC 5139 — ESO/INAF-VST/OmegaCAM. Acknowledgement: A. Grado, L. Limatola/INAF-Capodimonte Observatory
- NGC 7293 — ESO