Sources & licences
Checked August 2026 · The Quiet Sky
The Quiet Sky computes almost nothing of its own. The astronomy is arithmetic, but every number about the weather, every catalogue position, every image and every map tile is somebody else's work, fetched live. This page names all of it, with the licence each one is used under and the credit that licence asks for.
Wording here is quoted from the licences themselves rather than paraphrased. Where a licence asks for a specific sentence, that sentence appears below verbatim, spelling and all.
On this page
Weather and sky conditions
Open-Meteo
The hour-by-hour forecast that scores the night, the ensemble spread behind it, the regional cloud grid drawn on the map, the place-name search in the site picker, and the aerosol optical depth that floors the transparency score (their Air Quality API).
Licensed CC BY 4.0. Required credit: Weather data by Open-Meteo.com. The gazetteer behind the place-name search is GeoNames, which Open-Meteo credits in turn. The aerosol series originates with the Copernicus Atmosphere Monitoring Service, whose licence asks derived works to carry its own wording: contains modified Copernicus Atmosphere Monitoring Service information 2026.
Open-Meteo builds its forecasts from the open data of national weather services: Deutscher Wetterdienst (DWD), ECMWF, NOAA NCEP, Environment and Climate Change Canada, Météo-France, ItaliaMeteo (ARPAE), the Japan Meteorological Agency (JMA), the Norwegian Meteorological Institute, KNMI, DMI and the UK Met Office, each under its own licence as Open-Meteo lists on its licence page. Atmospheric forecasts from the UK Met Office are used under CC BY-SA 4.0.
Part of this data may be answered by an unmodified copy of the Open-Meteo server (AGPL-3.0) that we run ourselves from Open-Meteo's open data on AWS; the licences and credits above apply unchanged.
Environment and Climate Change Canada: MSC GeoMet
The GDPS and RDPS cloud values our server reads for the second opinion shown beside each hour. The map no longer draws ECCC images; its shading is the Open-Meteo regional grid above.
Used under the MSC Data Server End-use Licence. Where a specific product cannot be named, clause 3 offers this form, which is the one we use: contains information licenced under the Data Server End-use Licence of Environment and Climate Change Canada. The British "licenced" and the singular "Data Server" are the licence's own spelling.
Note what this is not: the licence grants use, not ownership. An earlier build printed "clouds © ECCC", which asserts a copyright the licence never transfers. That wording is gone and should not come back.
7Timer!
Seeing and transparency, treated throughout as optional enrichment. Run by the Shanghai Astronomical Observatory of the Chinese Academy of Sciences, computed from the NOAA/NCEP Global Forecast System.
7Timer!'s published Term of Use, shown on every forecast page of the site, says the service is provided as-is and may be used freely, naming software "free or paid" explicitly and asking no permission for either; the operator would "certainly appreciate a note", and takes issues and suggestions through the project's GitHub tracker. An older line in the API documentation still reads non-commercial and asks developers to notify the operator about server load; the Term of Use is the site's newer and operative statement, and it is the one this app relies on. Recorded here with both citations precisely because the two pages differ.
Astronomical catalogues and imagery
SIMBAD and Sesame: Centre de Données astronomiques de Strasbourg
Target name resolution, the common-name corpus behind the search type-ahead, and object sizes.
Requested acknowledgement: This research has made use of the SIMBAD database, CDS, Strasbourg Astronomical Observatory, France; see the CDS acknowledgement page. The reference paper is Wenger et al. (2000), A&AS 143, 9.
hips2fits: Centre de Données astronomiques de Strasbourg
The framing preview in the target panel is a real survey cutout rendered on demand at the field of view of your rig, by the hips2fits service.
Requested acknowledgement: This research has made use of hips2fits, a tool developed at CDS, Strasbourg, France aiming at extracting FITS images from HiPS sky maps with respect to a WCS.
Pan-STARRS1 (PS1): the default sky survey
Northern targets are rendered from PanSTARRS DR1 colour (i/r/g). Its 3π footprint stops at declination −30°, which is why anything further south is routed to 2MASS instead.
The survey asks to be cited as Chambers, K. C., et al. (2016), The Pan-STARRS1 Surveys, and for the acknowledgement published at the PS1 public science archive: the surveys and archive were made possible through contributions by the Institute for Astronomy and the University of Hawaii, the Pan-STARRS Project Office, the Max Planck Society and its participating institutes, The Johns Hopkins University, Durham University, the University of Edinburgh, Queen's University Belfast, the Harvard-Smithsonian Center for Astrophysics, the Las Cumbres Observatory Global Telescope Network, the National Central University of Taiwan, the Space Telescope Science Institute, NASA, the National Science Foundation, the University of Maryland, Eötvös Loránd University and the Los Alamos National Laboratory. The full text is on that page and governs.
2MASS: the all-sky fallback survey
Southern targets, and anything PanSTARRS returns blank for.
Required acknowledgement: This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation.
Wikipedia / Wikimedia Foundation
The one-paragraph description under a resolved target, and its thumbnail, come from the Wikipedia REST summary endpoint.
Article text is licensed CC BY-SA 4.0; each summary shown links back to the article it came from, which is where the contributor history lives. Thumbnails are not covered by that licence. Images on Wikipedia carry their own, file-by-file (public domain, CC BY, CC BY-SA, occasionally fair use), and the summary endpoint does not return which. Follow the article link for the file's own terms before reusing an image from here.
Light Pollution Atlas: David Lorenz
Zenith sky brightness and the darkest-horizon sweep are decoded from the VIIRS-derived binary tiles of the Light Pollution Atlas, by David Lorenz.
No formal licence is attached to the atlas; the author's stated request is that his maps not be conflated with the Bortle scale. This app honours that: it reports an SQM figure, and where it offers a Bortle class it is labelled an approximation, because zenith brightness and whole-sky Bortle class only correlate loosely.
The map
OpenFreeMap
The basemap under the sightline view is served by OpenFreeMap (tiles.openfreemap.org), the provider selected in config/map.php. Change the provider and this page, the map control and the privacy policy all follow; none of the three restates it by hand.
Credit, in the order the licence asks for it: OpenFreeMap · OpenMapTiles · OpenStreetMap contributors. Free for commercial use with no key; tiles built from OpenMapTiles and OpenStreetMap data under ODbL, and the public instance carries no SLA. See the provider's attribution terms.
OpenStreetMap
Every basemap option here is rendered from OpenStreetMap data, contributed by its mappers and licensed under the Open Data Commons Open Database License. Required credit: © OpenStreetMap contributors; see the OSM copyright page.
Typefaces and bundled software
The interface uses self-hosted EB Garamond for headings and Instrument Sans for content, controls and forecast data. Both are licensed under the SIL Open Font License 1.1. The new design uses self-hosted Manrope for its interface and JetBrains Mono for forecast data, under the same licence.
The page ships Vue and Laravel (MIT) and Leaflet (BSD 2-Clause), including Leaflet's own control and marker images. Both licences ask for their copyright notice to travel with the distributed code; the full texts sit beside each package in the repository's node_modules and vendor trees.
The icons in the visible sky panel and its first-visit step are from Iconsax, by Vuesax, as packaged in vue-iconsax by Emad Moghimi (MIT). Only the icons the panel uses are copied into the page, as their original path data. The QR code that opens a spot on a phone is drawn in the browser by node-qrcode by Ryan Day (MIT), loaded only when that card is shown.
What is not here
The astronomy (sun and moon positions, twilight windows, altitude and azimuth, angular separations) is computed in this application from published algorithms, not fetched. The scoring model, its gates and penalties, is ours. ACCURACY.md in the repository sets out how much that is worth, including the claims it does not yet earn.
Something credited wrongly, or not at all? That is a bug like any other; the contact page says where to send it.