# SkyLumi — Image & Data Credits SkyLumi composites publicly-licensed sky imagery and catalog data from several sources. This page lists every external asset bundled with the app. ## Generated (stylized) mode visual retune (issue #326) The Earthrise reference image (`docs/issue-assets/generated-mode-reference-earthrise.png`) is a photographic/composite image used as a visual reference only. The Generated sky look is recreated procedurally from the Brunier panorama, real catalog data, and original shaders; no pixels or assets from the reference are used, and the result is a stylistic approximation, not a reproduction — never presented as this app's own astrophotography. ## Black-hole visualization provenance The `sgr_a` hero scenario is clean-room application code. Its technique is informed by **dgreenheck/webgpu-black-hole** (MIT) and **oseiskar/black-hole** (MIT): - - No upstream imagery or Shadertoy code is shipped. The scenario is a Schwarzschild-geodesic visualization, not telescope imagery; the surrounding sky is the Brunier panorama credited below. ## Planetary-nebula procedural rendering The M57 scenario's volume and knot shaders are clean-room code using the project's own DreamSky value-noise basis. The curl-noise technique follows the mathematical description in Bridson, Hourihan & Nordenstam (2007), ; no Shadertoy or other CC BY-NC-SA shader code was copied. M57's bundled sprite credit remains the NASA/ESA Hubble credit in `src/data/dsos.ts`. ## Sky background panorama **"The Milky Way panorama"** by **Serge Brunier (ESO)**. - Source: - Image: `assets/sky/sky_8k.jpg` (4000×2000 equirectangular JPEG, ~4.6 MB) - License: **Creative Commons Attribution 4.0 International (CC BY 4.0)** - Credit string (visible in app footer): `ESO / S. Brunier` ESO's general copyright policy: ## High-resolution sky tiles (HiPS) — Photographic mode only The default **Stylized** sky background does not load any photographic tiles — it is rendered from the Brunier panorama (above) plus the HYG catalog (below) plus DSO sprites. The credits below apply when the user enables the optional **Photographic** sky-style from the Settings panel. In Photographic mode, SkyLumi streams progressively-detailed photographic sky tiles from the Centre de Données astronomiques de Strasbourg (CDS) Aladin HiPS service. Each tile tries: 1. **Pan-STARRS DR1** color-z-zg-g (Pan-STARRS1 Science Consortium, IfA Hawaii). - Source: - Coverage: north of Dec ≈ -30°. - Reference: Chambers et al. 2016, arXiv:1612.05560. 2. **DSS2 / DSSColor** (STScI Digitized Sky Survey, second epoch). - Source: - Coverage: full sky. Southern-sky fallback; also used for the low-res Allsky preview that paints in the first frame. - **STScI confirmed (2026-08-17):** free to use in SkyLumi while we do not charge for access to DSS data. Keep STScI and plate-holder (AAO/ROE, Caltech, AURA) attribution visible. - The Norder-3 Allsky preview specifically is self-hosted as a WebP re-encode (`public/assets/sky/dss2-allsky-n3.webp`, `scripts/build-dss2-allsky-preview.ts`, same source/license as above) — a same-origin perf optimization for the app's default view, not a separate work. Spectral-band Allsky mosaics (Hα/IR/X-ray) still stream live from CDS. (SkyMapper DR1 was previously included in the chain but produced visible colour-blown rectangular CCD-edge artefacts in many southern tiles; we fall through to DSS2 instead. DSS2 has subtle photographic-plate brightness steps but produces a uniformly continuous image.) For tiles below Dec ≈ -30° we skip the PanSTARRS attempt and go straight to DSS2 — saves one HTTP round-trip per tile. Tiles are organised in the **HEALPix** "nested" scheme described by Górski et al. (2005), ApJ 622, 759. All three surveys are made publicly available via CDS and are credited per their respective terms (CDS attribution required; STScI / Pan-STARRS / SkyMapper terms permit reuse with attribution). The on-screen credit is `CDS / Pan-STARRS / SkyMapper / STScI DSS`. **Rubin Observatory First Look** (sparse overlay, story-gated) — not part of the full-sky chain. While the "Rubin's first look" story is open, the app composites PNG HiPS tiles from CDS `P/Rubin/FirstLook` () over the existing map. Coverage is 29 square degrees (Virgo Cluster mosaic + Trifid and Lagoon mosaic). A missing tile is a 404, never a DSS2 fallback. HiPS packaging: ODbL-1.0. Images: CC BY 4.0. Credit: NSF–DOE Vera C. Rubin Observatory/NOIRLab/SLAC/AURA. `obs_copyright` on the HiPS properties file: `RubinObs/NOIRLab/SLAC/NSF/DOE/AURA`. **Static default-view preview** (`public/assets/sky/default-view-preview.webp`, ~48KB) — a real screen capture of the app's own default launch view (Orion, DSS2 survey, real constellation lines, no synthetic content). It depicts the same DSS2 DSSColor imagery as the Allsky preview above; the same STScI free-use confirmation and attribution requirements apply to this derivative. Shown as an instant full-viewport backdrop while the JS bundle downloads/parses (index.html's inline bootstrap script, `src/lib/defaultViewPreview.ts`), then removed once the live WebGL scene paints its first real frame. Captured manually via the app's own `capturePngBlob()` API at RA 84.23°, Dec −3.25°, FOV 28° (the default view — `ORION_DEFAULT_RA/DEC` in `src/state/store.ts`, `LIFE_SIZE_FOV_DEG` in `src/controls/zoomDetent.ts`), downscaled to 1280×720 and re-encoded to WebP q88. Regenerate if the default view ever changes: load the app with a clean `localStorage` at that RA/Dec/FOV, run `await window.skyAtlas.capturePngBlob({})` in the console, downscale and re-encode (`sharp(...).webp({quality:88})`), and replace the file — there's no automated build script for this one step, since it requires an actual running browser/WebGL session to capture from. ## Wavelength bands (issue #290) — Photographic mode only The Wavelength picker next to the image-source picker (Photographic mode) lets you REPLACE the visible-light survey above with a whole-sky imaging survey at a different wavelength. These are full-sky HiPS surveys streamed from CDS, same as the visible-light chain above, but each is its own self-contained dataset — never blended with the optical imagery. 1. **Hα (hydrogen-alpha)** — Finkbeiner (2003/2004) all-sky Hα composite, built from SHASSA, VTSS, and WHAM survey data. - Source: - Coverage: full sky, galactic frame. Native resolution ≈ 6 arcmin — shown Allsky-only (no deep zoom) since that's already close to native. - Reference: Finkbeiner, D. P. 2003, ApJS, 146, 407. 2. **Infrared** — 2MASS (Two Micron All Sky Survey) J/H/Ks color. - Source: - Coverage: full sky, equatorial frame. Pixel scale ≈ 2 arcsec. - Credit: University of Massachusetts and IPAC/Caltech (funded by NASA and NSF). 3. **X-ray** — ROSAT All-Sky Survey (RASS). - Source: - Coverage: full sky, equatorial frame. Angular resolution ≈ 2 arcmin. - Credit: Max Planck Institute for Extraterrestrial Physics (MPE). All three are HEALPixed and served by CDS (same mirror/attribution terms as the visible-light chain above; CDS attribution required). ## Star catalog **AT-HYG Database v3.3** (HYG: Hipparcos / Yale / Gliese — extended with **Tycho-2** and **Gaia DR3**) by David Nash. - Source: (and the original ); downloaded via the project's Codeberg mirror, . - License: **Creative Commons Attribution-ShareAlike — CC BY-SA 4.0**. ShareAlike applies to the derived `.bin` data file (attribute + link license + note the magnitude-filter/binary conversion); it does **not** extend to the app code. Underlying Gaia data: © ESA/Gaia/DPAC — the Gaia DR3 documentation requires credit to "ESA/Gaia/DPAC"; ESA's Gaia data licence page currently states distribution under CC BY-NC 3.0 IGO (it stated "open and free to use, provided credit is given to 'ESA/Gaia/DPAC'" until early 2025). Tycho-2 is public. - Used to build the binary star catalog `assets/stars/hyg_mag10.bin` (~328k stars to apparent magnitude ≤ 10, from the `athyg_33_reduced_m10` subset). These are real measured positions and populate both sky-styles. Since issue #289 the binary also carries each star's measured Gaia DR3/Hipparcos proper motion (mas/yr) in a trailing v2 block, used only by the opt-in "Proper motion" Hero Scenario (linear extrapolation of real measured motion, never invented) — inert everywhere else in the app. The per-star magnitude is kept on the GPU so the **Star density** slider can reveal or hide fainter stars at render time (default cutoff magnitude 8.5 ≈ 150k stars, a rich photographic-looking field; lower toward 6 for the recognizable naked-eye sky, or raise to 10 for the full catalog). The renderer additionally fades sub-pixel-size stars to alpha 0 via shader so the catalog never degenerates into screen-pixel noise. (Smaller `hyg_mag6.bin` / `hyg_mag7.5.bin` / `hyg_mag9.bin` binaries are also emitted by the build script.) The brightest ~50 stars (apparent magnitude ≤ 2) are drawn with an additional softer additive halo via `BrightStarBloom`, so prominent stars like Sirius, Vega and Betelgeuse visibly **bloom** instead of looking like generic dots. When **Landscape** mode is enabled, the star shader applies a simple atmospheric extinction curve — stars within ~25° of the horizon dim and redden, below the horizon fade out. Off by default in equatorial mode. ## City lookup **GeoNames** `cities15000` dataset (all cities with population > 15,000, plus every national/first-order-administrative capital regardless of population) and the `admin1CodesASCII` state/province name table, by the GeoNames contributors. - Source: , downloaded from . - License: **Creative Commons Attribution 4.0 — CC BY 4.0**. - Used to build `assets/cities.json` (~34k cities: name, ASCII name, country code, state/province, coordinates, population — see `scripts/build-cities.ts`). Powers the location popover's "near you" default and live city search (issue #594); raw latitude/longitude entry remains available as an advanced fallback for dark-sky sites away from any city. A short hand-curated list of native-spelling / English-exonym alternate names (e.g. "München" ↔ "Munich", "Köln" → "Cologne") is layered on for ~25 iconic world cities so common searches in either spelling resolve; it is not an exhaustive translation of the source's `alternatenames` column, which was intentionally dropped to keep the shipped asset small (~2.2 MB raw / ~880 KB gzipped) and free of transliteration noise. ## Constellations **Stellarium "Western" sky culture** — star pair indices for connecting Hipparcos stars into constellation figures. - Source: - License: the Western/"Modern" sky culture's text and line data are **CC BY-SA** (per the culture's `description.md`); the repo's AGPL-3.0 file covers tooling only, not the data — the earlier "GPL-2.0" label was wrong. We use only the line-pair data (HIP-number pairs), not Johan Meuris's Free-Art-License illustrations. The 88 IAU constellations/boundaries are themselves public domain; Stellarium maintainers have explicitly OK'd commercial reuse with attribution. ShareAlike applies to the derived `constellations.json`, not the app code. **CDS/VizieR catalog VI/49** — "Constellation Boundary Data" (Davenhall & Leggett 1989), transcribing the official 1930 Delporte IAU boundary delimitation, used for point-in-constellation lookup (which constellation a given sky position is actually inside) rather than for drawing lines. VI/49's own ReadMe recommends its companion catalog, VI/42 (Roman 1987), for that exact purpose and describes VI/49 itself as better suited to chart/atlas construction — this app uses VI/49 anyway, for its machine-readable polygon corners, and independently cross-checked the result against ~400k probe points using Roman's own VI/42 algorithm as an oracle (zero disagreements beyond quantization noise). - Source: - License: the underlying 1930 Delporte boundary delimitation, formalized by the IAU, is public domain. VizieR's own site-wide terms () ask that original authors and publication references be cited for scientific use and that a VizieR acknowledgment "would be appreciated" — CDS/VizieR is credited here on that basis, the same as the CDS Aladin HiPS credit above. See docs/LICENSING-AND-ASSETS.md §3.4a. ## Landscape panorama **Stellarium "Guereins" landscape** (TBD — to be downloaded in Phase 6). - Source: - License: CC BY-SA, attribution to original photographer (Stellarium contributors). **"Sentinel Dome Panorama"** by AWBridges, via Wikimedia Commons — the optional "Yosemite" landscape style's horizon strip (`assets/landscape/yosemite-panorama-alpha.webp`). - Source: - License: CC BY-SA 3.0 Unported (). - Modifications: cropped to a horizon band, sky removed (alpha), darkened to a night rendition. The derived image file remains CC BY-SA 3.0; pipeline: `scripts/build-yosemite-horizon.mjs`. ## Deep-sky catalog — bulk NGC/IC tier (issue #1514) **OpenNGC**, by Mattia Verga and contributors. - Source: , `database_files/NGC.csv`, pinned commit `da90466031b0372c896588b85be6016c617e205b` (2026-07-26). - License: **Creative Commons Attribution-ShareAlike 4.0 International — CC BY-SA 4.0**. ShareAlike applies to the derived `assets/dso/ngc_bulk.bin` + `ngc_bulk_names.json` files (attribute + link the license + note the magnitude/major-axis filter and binary conversion — see `scripts/build-ngc.ts`); it does **not** extend to the app code. - Used to build a bulk deep-sky tier (~11,231 galaxies/clusters/nebulae — everything OpenNGC catalogues with both a measured magnitude and major axis, minus the 137 objects already in the curated catalog below) — see `docs/LICENSING-AND-ASSETS.md` §3.4c for the full funnel and current wiring status. **d3-celestial**, by Olaf Frohn — credited here for the first time (2026-08-20, issue #1514): the curated 137-object catalog immediately below was originally built from d3-celestial's Messier list and this credit had been missing. - Source: . - License: **BSD-3-Clause**. Copyright (c) 2015, Olaf Frohn. ## DSO sprites All deep-sky-object sprites are hand-curated from the following sources. **All are CC BY 4.0 and require visible attribution with the exact, unaltered per-image credit string** (a flat "ESO" / "ESA/Hubble" is not compliant). Note: ESA/Hubble images via `cdn.esahubble.org` are **CC BY 4.0, NOT public domain** — the earlier "public domain" note for Hubble sprites was wrong. No institution logos. - ESO image archive (CC BY 4.0): - NASA / ESA Hubble — ESA/Hubble distribution (CC BY 4.0): - NASA / ESA / CSA JWST image gallery (CC BY 4.0): - NOIRLab Image Gallery (CC BY 4.0): Per-sprite credit, source URL, and license details are exposed in the in-app **Object Info** card. See `src/data/dsos.ts` for the machine-readable catalog. **Folder split (2026-08-06) — astrometric, not licensing.** The 53 sprites live in `enabled/` (5) or `disabled/` (48) under `public/assets/sprites/`. Only the `enabled/` ones have a verified sky footprint and are drawn as celestial overlays; the rest are shown as photographs in Object Info, the hover card and search. **All 53 still ship and every credit above still applies to all of them** — nothing here is affected by which folder a file sits in. ## Storybook imagery (issue #1145) The storybook asset directory contains 64 local WebPs used by the "Tonight's Wonders" stories: 51 fetched photographs/artist impressions, 9 computed figures, and 4 generated illustrations. The fetched photo/artist-impression rows follow the same attribution rules as the DSO sprites above: **exact, unaltered per-image credit strings**, no institution logos. - ESO image archive (CC BY 4.0): - NASA / ESA Hubble — ESA/Hubble distribution (CC BY 4.0): - NASA / ESA / CSA Webb — ESA/Webb distribution (CC BY 4.0): - NOIRLab Image Gallery (CC BY 4.0): - NASA image archives (free use with credit): Current split: **35 CC BY 4.0, 15 NASA, 1 public-domain (CC0 1.0)**. The machine-readable record — direct source URL, verbatim credit, licence, and kind — is `scripts/storybook-image-manifest.ts` (the curated, human-reviewed input) and the generated `src/data/storybook/images.ts`. Per-image credit is shown on the story card itself. **Nothing here is DSS2-derived, deliberately.** Two natural picks were rejected on exactly that ground: ESO's large Virgo cluster mosaic (`eso0919c`, credited "ESO/Digitized Sky Survey 2") and the Hubble press image for the Methuselah star (`opo1308a`, credited to the DSS). DSS2 is cleared for the free app (STScI 2026-08-17); storybook still avoids it for cleaner per-card licences. See `docs/LICENSING-AND-ASSETS.md`. **Honesty flags are data, not convention.** Ten images are artist's impressions — every exoplanet (none has ever been photographed), plus Voyager 1 in flight, Gaia BH1's invisible companion, and Tabby's Star — and each is badged as art on the card. Four more are stand-ins that illustrate a story rather than portray its subject, and each carries its own disclosure line. This is what the storybook's opening promise ("when something is an artist's guess, I'll say so") costs in practice. **Starman/Roadster photograph.** The card uses [Elon Musk's Tesla Roadster (40143096241).jpg](https://commons.wikimedia.org/wiki/File:Elon_Musk%27s_Tesla_Roadster_(40143096241).jpg), an image by **SpaceX** sourced from the Falcon Heavy Demo Mission Flickr page. Wikimedia Commons records SpaceX's public-domain dedication and CC0 1.0 status; the original is a 1,920×1,080 JPEG. The direct downloaded source and exact attribution are pinned in `scripts/storybook-image-manifest.ts`. ## DSO add-on images **None are currently active (2026-08-06).** The one add-on ever built, M31 below, is switched off via `enabled: false` in `src/data/dso-addons.ts` — Andromeda already reads well straight from the survey imagery, so a second Andromeda on top of it only risked doubling the disk. The asset still ships and its credit below still applies if it is ever switched back on. **M31 / Andromeda Galaxy add-on prototype** (inactive) - Source: NASA SVS, - Source asset: `M31_Wide.jpg` - Credit: Swift image: NASA/Swift/Stefan Immler (GSFC) and Erin Grand (UMCP); Optical image: Bill Schoening, Vanessa Harvey/REU program/NOAO/AURA/NSF. - Processing: local deterministic alpha extraction and color grade via `scripts/build-dso-addons.mjs`. **Resolved (2026-06-11):** the former DSS2-sourced `smc` sprite (AAO/ROE non-commercial restriction) has been replaced with ESO's VISTA VMC survey image (`eso1714a`, CC BY 4.0). No DSS2-derived base SMC sprite remains. **AI-generated sprite (2026-06-11): `m42` (Orion Nebula).** The M42 sprite is an **AI-generated artistic reconstruction** (Google Gemini image model), digitally re-rendered from CC BY 4.0 reference imagery: ESO/Igor Chekalin (`eso1103a`), ESO/VISTA (`eso1625a`), and NASA/ESA Hubble heic0601a (M. Robberto / HST Orion Treasury Project Team). It is an illustration of the full ~85'×60' nebula fan, not a calibrated photograph. Workflow: `scripts/generate-m42-sprite.mjs`. **Synthetic 3D volume, close-zoom only (2026-07-13, issue #291): `m42` (Orion Nebula).** At tight FOV (photographic-style close zoom, stylized mode) M42 crossfades from the flat sprite above into a raymarched volumetric effect. The density field is a DETERMINISTIC, DISCLOSED ARTISTIC EXTRAPOLATION baked offline from the sprite above (`scripts/build-m42-volume.ts`) — a single 2D image carries no true depth information, so this is an artistic derivative of an artistic derivative, not a measurement of M42's real 3D structure. See that script's and `src/scene/effects/m42Volume.ts`'s doc comments for the full method (brightness-weighted synthetic z-thickness + noise, renormalized per column so it crossfades seamlessly with the flat sprite). Disclosed in-app via the same `m42` credit string above. **AI star-removal overlays (2026-06-23, issue #103): 17 DSO sprites.** These sprites are real CC BY 4.0 astrophotos processed through the Google Gemini image model (`gemini-3.1-flash-image`) to remove foreground/background **stars and the sky background**, leaving only the object isolated on pure black so it composites via the DSOSprites SCREEN blend. The structure, colour and detail of the object are the **original photograph's** — only stars were removed. This is disclosed per-object in the in-app Object Info card (`credit` = "AI star-removal (Google Gemini) from "). Workflow: `scripts/dso-overlays.mjs` (star-removal) → `scripts/build-sprites-clean.ts --overlays` (falloff + WebP). Per-object base sources (all CC BY 4.0): - ESO (CC BY 4.0): `m16` (eso0926a), `m1` (eso9948f), `m33` (eso1424a), `m17` (eso1119a), `helix` (eso0907a), `eta-car` (eso0905a) - NASA/ESA Hubble — ESA/Hubble (CC BY 4.0): `m57` (heic1310a), `m104` (opo0328a), `m101` (heic0602a), `m82` (heic0604a) - NSF NOIRLab (CC BY 4.0): `m8` (noao-m8), `m20` (m20johnson, Adam Block), `m27` (noao-m27), `m51` (noao0124a, T. Rector), `m45` (noao-m45), `m81` (noao-m81, T. Rector), `ngc2237` (noao-rosette, T. A. Rector) **DSS2-derived overlays — `m31` and `ngc7000`.** The star-removal pipeline also produced overlays for M31 (from `heic1112f`'s DSS2-derived context) and NGC 7000 (from a CDS DSS2 4° cutout). Provenance is attributed to STScI and the plate holders (AAO/ROE, Caltech, AURA). STScI confirmed (2026-08-17) that SkyLumi may use DSS data while access is not charged for. Reassess before any paid/paywalled reuse. M42 keeps its owner-approved bespoke sprite (not the overlay) — see `OVERLAY_KEEP_EXISTING`. ## Chandra "Galactic Gems" companion imagery (issue #1999) **Five objects** — M82, M104 (Sombrero), M106, M33 (Triangulum), and Centaurus A (NGC 5128) — show a second, explicitly captioned image on their Object Info card: a NASA/CXC "Galactic Gems" press composite released 2026-08-25, combining Chandra X-ray data with optical (and, for some objects, infrared or ultraviolet) imagery from other observatories. **These are false-colour, multi-wavelength composites, never a photograph of what the object looks like to the eye** — each carries structure (X-ray superwinds, haloes, polarimetry) invisible in real starlight. Every card caption states the real wavelength layers and observatories for THAT object and says plainly that it is not the true-color view; source data and full per-object provenance are in `assets-src/chandra-gems/` (acquired PR #2000). Licence basis: the [CXC image use policy](https://chandra.harvard.edu/photo/image_use.html) — NASA/CXC/SAO material carries no copyright claim, free use with credit requested; every third-party layer used below is an institutional NASA/ESA/ ESO/NOIRLab credit, never a named individual/amateur rights holder. This composite imagery is strictly SECONDARY: it is never the card's primary hero image, and it is never drawn on the sky — see `src/data/chandra-companion-images.ts`'s doc comment for why that module deliberately carries no ra/dec/fov/rotation. - **M82** — Credit: X-ray: NASA/CXC/SAO; Optical: NASA/ESA/STScI; Infrared: NASA/ESA/CSA/STScI; Image Processing: NASA/CXC/SAO/L. Frattare, J. Major, and K. Arcand Source: - **M104 (Sombrero)** — Credit: X-ray: NASA/CXC/SAO; Optical:NASA/Hubble Heritage Team/AURA/STScI; Infrared: NASA/ESA/CSA/STScI; Image Processing: NASA/CXC/SAO/L. Frattare Source: - **M106** — Credit: X-ray: NASA/CXC/SAO; Optical: NASA/ESA/STScI; Infrared: NASA/ESA/CSA/STScI; Image Processing: NASA/CXC/SAO/L. Frattare (Release page labels this object "NGC 4258"; M106 is its Messier designation.) Source: - **M33 (Triangulum)** — Credit: X-ray: NASA/CXC/SAO; Optical: ESO/VLT; UV: NASA/Swift; Image Processing: NASA/CXC/SAO/L. Frattare ESO imagery is CC BY 4.0. Source: - **Centaurus A (NGC 5128)** — Credit: X-ray: (Chandra) NASA/CXC/SAO, X-ray (IXPE): NASA/MSFC; Optical: ESO; Infrared: NASA/ESA/CSA/STScI; Image Processing: NASA/CXC/SAO/L. Frattare, K. Arcand, and J. Major ESO imagery is CC BY 4.0. Source: The remaining six freely-usable images from this release (NGC 1672, NGC 660, NGC 1385, Arp 143, II Zw 096, NGC 3256) have no curated catalog entry yet and are not surfaced anywhere in the app. ## Deep-sky tile enhancements — AI-composited nebula cores (issue #1439, attribution corrected #1744) **Twenty-seven deep-sky objects** render with an AI-composited core over DSS2 survey imagery in Photographic survey mode, gated by the Sky-tab **"Deep sky overlays"** switch (default on). This is a different product from the DSO sprites/overlays above: it composites onto the live HiPS survey tile itself (`CleanedPatchLayer`), not a separate sprite layer. What renders is decided by the rows in `src/data/cleaned-patches.ts`, NOT by `review` in `shared/tile-blends.json` — those two sets are related but have drifted apart before, so this list is derived from the rows. Today twenty-seven objects render; the registry holds seventy-one entries, the rest being candidates with no rows. `m42` was re-approved by the owner on 2026-08-30 and renders; `ngc7000` is parked (`review: 'todo'`) and its rows were removed 2026-08-28, so it no longer renders; `ngc891` was registered 2026-08-28 and renders. Ten more (M33, M81, NGC 5128, M83, M17, NGC 6946, NGC 7635, M78, M100, M110) were approved in-app by the owner on 2026-09-02 and render. Every object that renders is credited below, whatever its review state — the licence obligation follows the pixels a visitor actually sees, not the workflow status. - **What the model is instructed to touch:** the DSS2 plate's overexposed, detail-less white core only. The prompt (`docs/prompts/dso-blend.txt`) directs the model to leave everything outside that core untouched — see `docs/dso-tile-blend-pipeline.md` §8 for the verification method and its known failure modes (the pipeline has caught the model deviating from this instruction before — stylization drift and fabricated structure on M27's first pass, §3). - **The background tile the core is composited onto is always DSS2** — the same DSS2/STScI provenance already disclosed above under "DSO sprites" ("DSS2-derived overlays"). DSS2 is cleared for this free app (STScI confirmed 2026-08-17, see above). - **Reference imagery and its license, per object — this is NOT uniform.** A real photograph of the same object guides what the AI model (Google Gemini, "nanobanana") composites into the core. Each credit below is copied verbatim from that object's `assets-src/tile-blends// reference-PROVENANCE.md` record — the sole source of truth for this section (never inferred, never carried over from a different image's credit): (Credit text below is kept unwrapped/verbatim on one line per object — even where long — because it must match `referenceCredit` in `shared/tile-blends.json` character-for-character; see `blendCreditCoverage.issue1744.test.ts`.) - **Lagoon Nebula (M8)** — ESO/VPHAS+ team. Licence: CC BY 4.0. - **Dumbbell Nebula (M27)** — Radan Mitrović (Радан Митровиќ), CC BY-SA 4.0, via Wikimedia Commons. - **Helix Nebula (NGC 7293)** — ESO. Licence: CC BY 4.0. - **Crab Nebula (M1)** — ESO / Manu Mejias. Licence: CC BY 4.0. - **Trifid Nebula (M20)** — NSF–DOE Vera C. Rubin Observatory/NOIRLab/SLAC/AURA. Licence: CC BY 4.0. - **Eagle Nebula (M16, Pillars of Creation)** — ESO. Licence: CC BY 4.0. - **Orion Nebula (M42)** — Astro.sin, CC BY-SA 4.0, via Wikimedia Commons. - **Rosette Nebula (NGC 2237)** — Mystery Ray, CC BY-SA 4.0, via Wikimedia Commons. - **Whirlpool Galaxy (M51)** — K. Rhode, M. Young and WIYN/NOIRLab/NSF/AURA. Licence: CC BY 4.0. - **Sunflower Galaxy (M63)** — Taavi Niittee (CC0 — attribution not required). Licence: CC0 1.0. - **Black Eye Galaxy (M64)** — KPNO/NOIRLab/NSF/AURA/Brandon Chadwell/Flynn Haase. Licence: CC BY 4.0. - **Sculptor Galaxy (NGC 253)** — ESO/INAF-VST Acknowledgement: A. Grado/L. Limatola/INAF-Capodimonte Observatory. Licence: CC BY 4.0. - **Cigar Galaxy (M82)** — KPNO/NOIRLab/NSF/AURA/Steve Peterson/Katy Garmany. Licence: CC BY 4.0. - **Needle Galaxy (NGC 4565)** — Ken Crawford, CC BY-SA 3.0. - **M106 (NGC 4258)** — KPNO/NOIRLab/NSF/AURA; Ack: PI M.T. Patterson (NMSU); processing T.A. Rector (UAA), M. Zamani, D. de Martin. Licence: CC BY 4.0. - **Silver Sliver Galaxy (NGC 891)** — KPNO/NOIRLab/NSF/AURA; Ack: PI M.T. Patterson (NMSU); processing T. Rector (UAA), M. Zamani, D. de Martin. Licence: CC BY 4.0. - **North America Nebula (NGC 7000)** — Giuseppe Donatiello (CC0 — attribution appreciated, not required). Licence: CC0 1.0. *(no longer renders — rows removed 2026-08-28; credit retained for prior releases)* - **Sombrero Galaxy (M104)** — NASA and The Hubble Heritage Team (STScI/AURA). Licence: STScI/HubbleSite material — usable without fee with credit (hubblesite copyright notice); **not CC-licensed**. - **Triangulum Galaxy (M33)** — ESO. Licence: CC BY 4.0. - **Bode's Galaxy (M81)** — Ken Crawford, CC BY-SA 4.0, via Wikimedia Commons. - **Centaurus A (NGC 5128)** — ESO. Licence: CC BY 4.0. - **Southern Pinwheel (M83)** — ESO. Licence: CC BY 4.0. - **Omega Nebula (M17)** — ESO/INAF-VST/OmegaCAM. Acknowledgement: OmegaCen/Astro-WISE/Kapteyn Institute. Licence: CC BY 4.0. - **Fireworks Galaxy (NGC 6946)** — KPNO/NOIRLab/NSF/AURA/T.A. Rector (University of Alaska Anchorage)/H. Schweiker (WIYN). Licence: CC BY 4.0. - **Bubble Nebula (NGC 7635)** — T.A. Rector (University of Alaska Anchorage), WIYN ODI team & WIYN/NOIRLab/NSF/AURA. Licence: CC BY 4.0. - **NGC 2068 Reflection Nebula (M78)** — T. A. Rector/University of Alaska Anchorage, H. Schweiker/WIYN and NOIRLab/NSF/AURA. Licence: CC BY 4.0. - **Pinwheel Spiral (M100)** — N.A.Sharp/NOIRLab/NSF/AURA. Licence: CC BY 4.0. - **M31 Companion (M110)** — NOIRLab/NSF/AURA. Licence: CC BY 4.0. Five of the twenty-seven (Dumbbell/M27, Rosette/NGC 2237, Needle/NGC 4565, Orion/M42, Bode's/M81) are credited under **CC BY-SA**, not CC BY — a ShareAlike term, distinct from the plain-attribution CC BY 4.0 that covers most of the rest. This section states that fact; whether/how ShareAlike applies to the derived blend artifact is a separate legal question the owner has not yet resolved (tracked on #1744). A fourth (Sombrero/M104) carries a different, non-CC Hubble Heritage/STScI copyright notice — stated above exactly as its provenance file states it, with no CC label invented for it. - **Independent of "Show repaired tiles":** the Debug-tab repair toggle governs only genuine survey-defect repairs (reflections, bad tiles, streaks) — a separate class inside the same renderer. Full pipeline: `docs/dso-tile-blend-pipeline.md`. **Source corrections (2026-06-11), with per-image credit lines verified 2026-09-01:** several sprites previously pointed at wrong archive subjects (finder charts, comparison strips, observatory photos) and were replaced with NSF NOIRLab / ESO images (CC BY 4.0). Full URL list in `scripts/build-sprites-clean.ts`. ⚠️ **NOIRLab states the full credit line is MANDATORY for fee-free use**, so each line below is reproduced exactly as that image's own page gives it — including `m97`'s missing space in "NRCof", which is NOIRLab's own rendering and not a typo to fix here. These are the strings `src/data/dsos.ts` carries and the Object Info card shows; the two must not drift. | object | image | credit line, verbatim from the licensor's page | |---|---|---| | `m11` | ESO `eso1430a` | ESO | | `m13` | `noao0103a` | N.A.Sharp, REU program/NOIRLab/NSF/AURA | | `m22` | `noao-m22` | N.A.Sharp, REU program/NOIRLab/NSF/AURA | | `m27` | `noao-m27` | REU program/NOIRLab/NSF/AURA | | `m57` | `noao-m57` | N.A.Sharp, REU program/NOIRLab/NSF/AURA | | `m63` | `noao-m63` | N.A.Sharp/NOIRLab/NSF/AURA | | `m87` | `noao-m87block` | KPNO/NOIRLab/NSF/AURA/Adam Block | | `m94` | `noao-m94` | Hillary Mathis, N.A.Sharp/NOIRLab/NSF/AURA | | `m97` | `geminiann10008a` | International Gemini Observatory/NOIRLab/NSF/AURA/Émilie Storer (Collège Charlemagne, QUE)/André-Nicolas Chéné (HIA/NRCof Canada)/T. Rector (U.Alaska, Anchorage). | | `hperchi` | `noao-hcper` | N.A.Sharp/NOIRLab/NSF/AURA | | `ngc6888` | `noao-04494` | T.A. Rector (NRAO/AUI/NSF and NOIRLab/NSF/AURA) | | `smc` | ESO `eso1714a` | ESO/VISTA VMC | **What was wrong before this pass.** Six of these read `"Source TBD"` in the catalog (`m11`, `m22`, `m63`, `m87`, `m94`, `m97`) and three carried an attribution belonging to a *different institution and a different image* than the sprite actually shown — `m13` credited "ESA / Hubble / NASA" with a `creditShort` of "ESO/VLT" for an NSF NOIRLab image, `m57` credited Hubble for a NOIRLab image, and `m27` had NOIRLab credit text pointing at an eso.org URL. The earlier note here said only "credit per image page — KPNO/NOAO/AURA/NSF", which described none of them exactly and let the drift sit unnoticed. CC BY 4.0 requires attribution to the actual licensor, so a confidently wrong credit is worse than a missing one. ⚠️ **`m31` and `m45` are NOT part of this batch, and this file used to say they were.** The list above previously named both, but neither appears in the source-URL list in `scripts/build-sprites-clean.ts` — which is the authority for what was actually re-fetched. `m31` appears in that file only as a command-line *example* (`build-sprites-clean.ts m42 m31`), which is easy to misread as a source entry. Their sprites are therefore NOT the `noao-m31`/`noao-m45` images, their existing credits stand, and an attribution was **not** rewritten for them on the strength of this file's own prose. Corroboration that they differ: the `noao-m31` page credits "T.A.Rector and B.A.Wolpa", while this file's old note said "Bill Schoening/Vanessa Harvey" — two different photographers for one supposed image, which is the tell that the prose list was never verified against the script. **`m42`** is not from this batch: its sprite is a COMPOSITE of three CC BY 4.0 images (`scripts/generate-m42-sprite.mjs`) and now credits all three — ESO/Igor Chekalin (`eso1103a`, WFI base); NASA, ESA, M. Robberto (STScI/ESA) and the Hubble Space Telescope Orion Treasury Project Team (`heic0601a`, core); ESO/H. Drass et al. (`eso1625a`, HAWK-I infrared). It previously named only two of the three and linked a fourth page. ⚠️ **`m83` is an OPEN LICENCE QUESTION, deliberately left as `"Source TBD"`.** It is one of the five sprites DRAWN ON THE SKY (`public/assets/sprites/enabled/`), yet no source is recorded for it anywhere in this repo: it is absent from `scripts/build-sprites-clean.ts`, absent from this file, and its only file history is #1025 moving it into `enabled/`. A credit was NOT invented for it. It needs either a sourced provenance or a move back to `disabled/` until one exists — a displayed image whose licence nobody can state is the risk here, and guessing would only hide it. **5 previously-missing sprites added (2026-07-17, issue #450):** `ngc7662`, `m67`, `m34`, `m110`, and `m35` had `sprite` references in `src/data/dsos.ts` pointing at `.webp` files that didn't exist, so their stylized-mode photo overlay silently failed. Sourced real astrophotos and ran them through the standard `scripts/build-sprites-clean.ts` pipeline: - **NGC 7662 (Blue Snowball Nebula)** — NASA/ESA Hubble, CC BY 4.0. Credit: Bruce Balick and Jason Alexander (University of Washington), Arsen Hajian (US Naval Observatory), Yervant Terzian (Cornell University), Mario Perinotto (University of Florence), Patrizio Patriarchi (Arcetri Observatory) and NASA/ESA. Source: - **M67 (King Cobra Cluster)** — NSF NOIRLab, CC BY 4.0. Credit: Nigel Sharp, Mark Hanna/NOIRLab/NSF/AURA. Source: - **M34** — NSF NOIRLab, CC BY 4.0. Credit: REU program/NOIRLab/NSF/AURA. Source: - **M110 (NGC 205)** — NSF NOIRLab, CC BY 4.0. Credit: NOIRLab/NSF/AURA. Source: - **M35 (Shoe-Buckle Cluster)** — NSF NOIRLab, CC BY 4.0. Credit: N.A. Sharp/NOIRLab/NSF/AURA. Source: (the source frame also shows NGC 2158, a fainter, unrelated background cluster in the same field — cropped out before processing so the M35 sprite shows only M35 itself). All 5 ids were also added to `src/data/sprite-manifest.ts`'s `AVAILABLE_SPRITE_IDS` (the runtime gate `DSOSprites.add()`/`hasSprite()` checks before ever attempting to load a sprite texture — without this, the `.webp` files alone would not have been enough to make the photos appear). ## Planet surface maps (Stylized mode) The realistic planet-systems layer (Stylized mode "Planets & moons" toggle) renders textured spheres from cylindrical surface maps, downscaled/re-encoded for the web (orientation unchanged; see `scripts/fetch-planet-textures.mjs` for the exact pipeline). Per-file source + license: ### Planet globes — Mercury → Neptune (Solar System Scope, CC BY 4.0) Replaced (#166, 2026-06-25) with the **Solar System Scope** 2k map set — a coherent, high-quality, correctly-lit set built from **NASA elevation + imagery** and published by Solar System Scope under **Creative Commons Attribution 4.0 International (CC BY 4.0)** — commercial use OK *with* attribution; **not** NC. This fixed the artificial look (the old maps were tiny/low-res, and Venus was a radar *surface* map rather than its cloud-tops). Downloaded at 2048×1024 and re-encoded for the web (orientation unchanged; sources kept in gitignored `assets-src/planets/`). - Source: **Solar System Scope** — (License: CC BY 4.0). Required credit: *"Textures by Solar System Scope (solarsystemscope.com), CC BY 4.0."* - `assets/planets/mercury.jpg` — `2k_mercury.jpg`. - `assets/planets/venus.jpg` — `2k_venus_atmosphere.jpg` (cloud-tops, so Venus shows its true featureless golden cloud disk + lit crescent, not radar terrain). - `assets/planets/mars.jpg` — `2k_mars.jpg`. - `assets/planets/jupiter.jpg` — `2k_jupiter.jpg`. - `assets/planets/saturn.jpg` — `2k_saturn.jpg`. - `assets/planets/uranus.jpg` — `2k_uranus.jpg` (a clearly-licensed CC BY 4.0 Uranus map, replacing the prior Stellarium one; CelestiaContent's CC BY-**NC** Uranus remains excluded). - `assets/planets/neptune.jpg` — `2k_neptune.jpg`. ### Jupiter's moons (CelestiaProject / CelestiaContent) Sourced from the **CelestiaProject / CelestiaContent** repository — community processings built on **NASA / JPL-Caltech / USGS** public-domain imagery — under **Creative Commons Attribution (CC BY)** licenses. - Source repo: (`textures/hires`) - `assets/planets/io.jpg` — **CC BY 4.0**. NASA/JPL-Caltech/ASI/USGS; NASA/JPL/SwRI/MSSS/G. Eichstädt/J. Perry/J. Rogers; ItzImcool; AstroChara. - `assets/planets/ganymede.jpg` — **CC BY 3.0**. © Askaniy Anpilogov; NASA/JPL-Caltech/ASI/USGS; NASA/JPL-Caltech/Björn Jónsson; NASA/JPL-Caltech/SwRI/MSSS/B. Swift. - `assets/planets/europa.jpg`, `assets/planets/callisto.jpg` — from the same CelestiaContent `textures/hires` set (CC BY family, NASA/JPL-Caltech/USGS base). **TODO before commercial release:** confirm the exact per-file CC BY author strings for these two (their REUSE `.license` sidecars were absent at fetch time). ### Saturn ring profile (procedural — no asset) The ring radial color/alpha profile is **generated procedurally at runtime** (`makeRingProfileTexture` in `src/scene/PlanetSystem.ts`): band radii (C/B/ Cassini division/A/Encke gap) are the real values, but the fine-scale banding is synthesized — a deliberately **stylized** profile, used because no clearly-licensed Cassini-derived radial scan was available. No third-party ring imagery is bundled. ### Moons & ephemerides The non-Galilean moons (Phobos/Deimos, Saturn's seven majors, the five Uranian moons, Triton) render as tinted spheres — no textures bundled. Moon positions/orbits use `astronomy-engine` for the Galileans and mean-element Keplerian orbits for the rest (JPL-derived elements as compiled in CelestiaContent `data/solarsys.ssc`; orbital elements are facts/data — see `src/astronomy/planetMoons.ts` for the per-system citations). Planet poles/rotation come from `astronomy-engine` (IAU rotation models). No bundled ephemeris data. ## Satellite orbital elements (TLEs) **TLE data: CelesTrak (celestrak.org)** — maintained by Dr. T.S. Kelso. - Source: (GP API, `stations` and `visual` groups, OMM/JSON format), fetched at runtime and cached locally. - CelesTrak data is free to use; credit "TLE data: CelesTrak (celestrak.org)". - A small bundled fallback set of TLEs (`src/data/satellite-seed.ts`) derives from the same source; the app age-gates it and labels it as non-live. - Satellite positions are propagated in-browser with **satellite.js** (MIT) — . Displayed brightnesses are estimates from standard-magnitude values (McCants/CelesTrak compilation convention) and are labeled as estimates in the UI. ## Satellite standard magnitudes (issue #962) **Standard-magnitude data: Mike McCants** (`quicksat.mag`, bundled in `quicksat.zip`). - Source: , fetched 2026-08-07. Dated 2010-06-04 in the archive. - No explicit license is stated anywhere on mmccants.org or in the bundled files. This is the same compilation Stellarium, Guide, and Heavensat all redistribute without a documented written grant; bundled here on that community-norm basis, an owner-reviewed decision — see `docs/LICENSING-AND-ASSETS.md` §3.4b for the full writeup. - Stored locally as generated `src/data/satellite-stdmag-table.ts` (`scripts/build-satellite-stdmag.ts`). ## ISS 3D model (issue #524) At deep zoom, aimed directly at the ISS, the generic satellite dot is replaced by NASA's real ISS 3D model. - Source: **NASA Visualization Technology Applications and Development (VTAD)**, published at (glTF, `ISS_stationary.glb`, originally ~42 MB). - License: **U.S. Government work — public domain** (17 U.S.C. §105; no copyright is asserted on works of the U.S. federal government). No attribution is legally required, but NASA is credited here per its own media usage guidelines, which also ask that use of NASA material **not imply or state that NASA endorses** a commercial product, service, or activity — this app makes no such claim. - The bundled file (`public/assets/satellites/iss.glb`, ~1.1 MB) is a re-encoded, decimated, and compressed derivative of NASA's original — not the original file. Pipeline (via `@gltf-transform/cli`, a dev dependency): duplicate-resource dedup, mesh simplification (meshoptimizer), Draco geometry compression, and WebP texture re-encoding at 256×256 (down from the source's 1024×1024 JPEGs) — the model never fills more than a small on-screen icon at the zoom level where it renders, so this loses no perceptible detail there. Geometry and materials are otherwise NASA's own modeling, unmodified in content. - The Draco decoder (`public/assets/satellites/draco/`, ~750 KB) is **Three.js's own vendored copy** (`node_modules/three/examples/jsm/libs/ draco/gltf/`, Google's Draco project, Apache 2.0) — bundled locally so decoding never depends on a third-party CDN. - The model is not rendered at true angular scale (real ISS ≈ 1 arcminute, a few px even at this zoom) — like the point-sprite dot it replaces, its on-screen size is floored to a fixed legible size (see `src/scene/IssModel.ts`). ## Satellite card images (issue #1724) The ISS, Tiangong, and generic-satellite Object Info cards each show a hero image above the identity sentence. - **AI-generated illustrations** (Google Gemini image model, `gemini-3.1-flash-image`, "nanobanana") — pure text-to-image generation, not derived from any specific source photograph. Unlike the DSO sprite overlays above, these are UI card art only: they are never placed on the sky as a scaled overlay, since (per this file's DSO sprite section) that would need a measured footprint this artwork doesn't have. - Workflow: `scripts/generate-satellite-images.mjs`. Raw generations live in `assets-src/satellite-images/raw/` (gitignored); the shipped files are `public/assets/satellites/{iss,tiangong,generic-satellite}-card.webp`. - The ISS and Tiangong images are artistic reconstructions depicting each station's real, distinctive silhouette (ISS's long truss with paired solar-array wings; Tiangong's T-shaped core-and-labs layout) — not calibrated photographs. The generic-satellite image is a representative illustration, not any specific real spacecraft. ## Fonts The Aurora UI typeface set is self-hosted (issue #243 Phase 0 — no external font CDN dependency, so a future Capacitor-wrapped native app shell can render its core UI offline). All four are **SIL Open Font License 1.1** (confirmed via the `ofl/` directory of the google/fonts repo), Latin subset only, and trimmed to only the weights actually used (verified against every `font-display` / `font-mono` / Tailwind font-weight utility in `src/`, and the `@font-face` block at the top of `src/site/site.css`): - **Space Grotesk** (weight 600 only) — Florian Karsten, - **Outfit** (weights 300, 400, 500, 600, 700) — Rodrigo Fuenzalida, - **IBM Plex Mono** (weight 400 only) — IBM, - **Sora** (variable, weights 400-700) — Jonathan Barnbrook / Soar Communications Group, — the marketing site's display face and the app's splash lockup. Two files: the Latin subset plus `latin-ext`. Files: `public/fonts/*.woff2` (~132 KB total), referenced via `@font-face` at the top of `src/index.css` (app) and `src/site/site.css` (marketing site). Bodoni Moda was the site's display face until 2026-08-23 and its files were removed when Sora replaced it — recover them from git history if it ever returns. No attribution string is required by the OFL for using the fonts as intended (unlike the CC BY-licensed imagery elsewhere on this page), but author/source credit is kept here for provenance. ## Libraries - **Three.js** (MIT) — - **React** (MIT) — - **Zustand** (MIT) — - **astronomy-engine** (MIT) — - **satellite.js** (MIT) — - **Fuse.js** (Apache 2.0) — - **Tailwind CSS** (MIT) — ## SkyLumi code **Proprietary — © Kiruna Labs. All rights reserved.** This is a private, closed-source project; no license to reuse the application code is granted. The third-party data and imagery above retain their own licenses (see each section), and their attribution obligations are honored independently of the application code.