Credits

Star map: the stars

Star positions and brightness come from the HYG database by David Nash (astronexus), licensed under Creative Commons Attribution-ShareAlike 4.0 (CC BY-SA 4.0). We use a trimmed copy (stars to magnitude 5.2; position, brightness, catalog number, name and constellation). That adapted file is shared under the same license: /sky/stars.json.

Star map: constellation lines

The constellation stick figures come from d3-celestial by Olaf Frohn (constellations.lines.json), used under its BSD 3-clause license:

Copyright (c) 2015, Olaf Frohn
All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.

2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

3. Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

Star map: places and time zones

Town names, coordinates and time zones come from GeoNames (cities of 15,000 people or more), licensed under Creative Commons Attribution 4.0 (CC BY 4.0). We use a trimmed copy, plus the GeoNames alternate names in other scripts (such as Москва or 東京) for towns of 100,000 or more. Daylight saving and past clock changes come from your browser's own time-zone database.

The sky is worked out with standard formulas (sidereal time and precession as in Jean Meeus, Astronomical Algorithms). You can check any star map in Stellarium.

Photos: models that run in your browser

• Face and object finding, and the in-browser background cut: MediaPipe by Google (BlazeFace, EfficientDet-Lite0, selfie multiclass segmentation, DeepLab v3), Apache License 2.0.
• Depth: Depth Anything V2 Small, Apache License 2.0.
• Photo enlarging: Real-ESRGAN (general x4v3), BSD 3-clause.
• Running the models: ONNX Runtime Web, MIT License. 3D previews: three.js, MIT License.
• Lettering fonts: Google Fonts, SIL Open Font License.