Colophon
How this site is made, and what it rests on
What First Rig is built with, what it collects and what it does not, how its numbers are checked, and every source of data it uses, with the license and the credit each one asks for. What changed and when is in the changelog; errors found and fixed are in the corrections log.
Built and served
First Rig is a Next.js site written in TypeScript, served from the founder’s own server with Cloudflare in front as a cache. There is no database and there are no accounts. The gear catalogue is typed data compiled into the site when it is built, and each tool keeps its inputs in the page address, so a result is a link you can share. The observatory guide and the guides are written in MDX and compiled at build time.
There are no ads and no sponsored content. There are no affiliate links on the site today; if any are added, they will be labeled, and they will not move a ranking (how the site makes money).
What is collected
Visits are counted with Cloudflare Web Analytics. It sets no cookies, so there is no consent banner, and Cloudflare adds it at the edge; it is not in the site’s code. It records the path of each page viewed and the path of the page the visitor came from. It does not record query strings, which is where every tool keeps your inputs: a link to your rig in the Backfocus Solver reaches the analytics as /tools/backfocus and nothing more. There is no other tracker on the site.
Two things stay in your browser. The Session Checklist keeps your ticks, the half of the night you chose and any checklists you customize, and the site remembers night mode, in local storage; none of it is sent anywhere. A checklist you share by link travels after the # in the address, a part browsers do not send to a server, and the page takes it out of the address as it loads. Sky from my location reads your position in the browser and fetches the map tile for your area, a 5° square; the coordinates are never sent, stored or written into the link.
How the numbers are checked
Every formula in the physics package carries a citation and a unit test built from a worked example in our physics reference. Where a test and a published value disagree, the site is treated as wrong until shown otherwise. Every catalogue row carries the link to the page it was keyed from, and the gear rows behind the Rig Reality Check stay marked unchecked until the founder has checked them by hand against that page. A figure that could not be confirmed on a maker’s own page is labeled unverified where it is used.
| Tests in the suite, in 53 files, counted 13 October 2026 | 1,348 |
| of them on the physics package | 410 |
| on the catalogue data | 423 |
| on the site's own logic and content | 515 |
| Gear rows behind the Rig Reality Check | 206 |
| of them checked by hand so far | 0 |
| Cameras and correctors in the Backfocus Solver | 112 |
| Backfocus figures labeled unverified | 22 |
| Sensor profiles in the Exposure Planner | 21 |
When a figure turns out to be wrong it goes into the corrections log, and the page it was on carries a dated note where the figure changed.
Data sources
Every source the site uses, what for, under which license, and the credit that license asks for, as we give it. Where a license asks us to say what we changed, the last column says. Each credit also appears where the data is used.
OpenNGC, tag v20260501
Mattia Verga
- Used for
- The angular sizes of the targets drawn in the Rig Reality Check's framing check, on the rig pages and in the framing tool, and the galaxies' position angles in the framing tool.
- License
- CC BY-SA 4.0
- Credit, and what we changed
- Target sizes: OpenNGC by Mattia Verga (tag v20260501), CC BY-SA 4.0. This table is shared under the same license.We keep the published major and minor axes of the targets we draw, unadjusted, and the position angle where OpenNGC gives a source for it, in a table of our own. That table is kept apart from the gear and price data and is shared under CC BY-SA 4.0.Also credited on: Rig Reality Check, how it is computedField of View & Framing, how it is computed
VIIRS Nighttime Lights (VNL) V2, annual 2024
Earth Observation Group, Payne Institute for Public Policy, Colorado School of Mines
- Used for
- The night-time radiance behind the sky-brightness model and the sky-from-location estimate.
- License
- CC BY 4.0
- Credit, and what we changed
- Earth Observation Group, Payne Institute for Public Policy, Colorado School of Mines. Elvidge, C.D., Zhizhin, M., Ghosh, T., Hsu, F-C., Taneja, J. (2021), “Annual time series of global VIIRS nighttime lights derived from monthly averages: 2012 to 2019”, Remote Sensing 13(5), 922.The map tiles this site serves under /skyglow/v1/ are derived from VNL 2024: each cell holds a distance-weighted sum of the radiance within 300 km, on a 60″ grid covering the lower 48 states. They are not the original data.Also credited on: Sky brightness method, note 1Beside each sky-from-location estimate
- Used for
- Our copy of VNL: the same EOG layer, served without a login.
- License
- CC BY 4.0
- Credit, and what we changed
- T. Hengl, OpenLandMap, Zenodo record 17294744.Also credited on: Sky brightness method, note 1
A simplified model of all-sky artificial sky glow derived from VIIRS Day/Night band data
Duriscoe, D.M., Anderson, S.J., Luginbuhl, C.B., Baugh, K.E. (2018)
- Used for
- The form of the sky-brightness model, and the measured sites in its Table 1 that set our calibration level.
- License
- CC BY 4.0
- Credit, and what we changed
- Duriscoe, D.M., Anderson, S.J., Luginbuhl, C.B., Baugh, K.E. (2018), JQSRT 214, 133–145, doi:10.1016/j.jqsrt.2018.04.028.We re-fitted the model's two shape constants for the zenith; the paper fitted them for the whole sky.Also credited on: Sky brightness method, note 2
Globe at Night, 2024 and 2025 data
NSF NOIRLab
- Used for
- Handheld sky-quality readings: the 2024 set fits the model's shape and the 2025 set tests it. Not redistributed.
- License
- CC BY 4.0
- Credit, and what we changed
- Globe at Night, NSF NOIRLab.Also credited on: Sky brightness method, note 3
Night Skies Program measurements
U.S. National Park Service, Natural Sounds and Night Skies Division
- Used for
- Testing the model out of sample, and the 21.83 mag/arcsec² median natural sky.
- License
- U.S. public domain
- Credit, and what we changed
- No credit is required. We cite the National Park Service, and never use the observers' names the data carries.Also credited on: Sky brightness method, note 4
Worldwide variations in artificial skyglow, supplementary tables S2 and S3
Kyba, C.C.M. et al. (2015)
- Used for
- Testing the model against 45 fixed sky-quality meters on four continents. Validation only: no row is published.
- Credit, and what we changed
- Kyba, C.C.M. et al. (2015), Scientific Reports 5, 8409.Also credited on: Sky brightness method, note 5
The new world atlas of artificial night sky brightness
Falchi, F. et al. (2016)
- Used for
- Two published values: the 22.0 mag/arcsec² reference sky and its luminance. None of the atlas data.
- License
- Article and atlas CC BY-NC 4.0; facts only are used
- Credit, and what we changed
- Falchi, F. et al. (2016), Science Advances 2, e1600377.Also credited on: Sky brightness method, note 6
Manufacturer pages, manuals and drawings
ZWO, QHYCCD, Player One, ToupTek, Sky-Watcher, Celestron, Askar, William Optics, iOptron and the other makers in the catalogue
- Used for
- Every specification in the gear catalogue, re-keyed by hand as a figure with the page it came from.
- License
- Facts, which no license covers. No image or marketing text is copied.
- Credit, and what we changed
- The source link on each catalogue row.Also credited on: Backfocus SolverRig Reality Check
Store listings
Makers' own stores and U.S. retailers
- Used for
- The dated prices in the Rig Reality Check.
- License
- Facts, which no license covers
- Credit, and what we changed
- The seller, the date read and a link, on each price.Also credited on: Rig Reality Check
The target-size line the Rig Reality Check prints reads: “Target sizes: OpenNGC by Mattia Verga (tag v20260501), CC BY-SA 4.0. This table is shared under the same license.” It links here, to the OpenNGC, tag v20260501 row above, for the source and license.
Software and type
The site’s own code is not open source. These are the open-source parts it is built on, each under its own license, with the copyright line from that license. The build strips license comments from the code your browser loads, so for the MIT code marked “sent to your browser” the notice is here: the copyright lines in the table and the license text below it.
| Name | Version | License | Copyright | Where it runs |
|---|---|---|---|---|
| Geist and Geist MonoEvery page's type. The font files are fetched when the site is built and served from this site, so no visitor request goes to a font service. Each file carries its copyright line and license in its own metadata. | 1.800 and 1.701 | SIL Open Font License 1.1 | Copyright 2024 The Geist Project Authors | Sent to your browser |
| three.jsThe 3D viewer on the observatory model page, and only there. The model it shows is the founder's own. | 0.186.1 | MIT | Copyright © 2010-2026 three.js authors | Sent to your browser |
| Next.jsThe framework every page is built and served with. | 16.3.1 | MIT | Copyright (c) 2025 Vercel, Inc. | Sent to your browser |
| ReactThe interface of every page and tool. | 19.2.8 | MIT | Copyright (c) Meta Platforms, Inc. and affiliates. | Sent to your browser |
| Tailwind CSSGenerates the stylesheet from the design tokens. | 4.3.3 | MIT | Copyright (c) Tailwind Labs, Inc. | Build only |
| MDXCompiles the observatory guide's chapters and the guides. | 3.1.1 | MIT | Copyright (c) 2017 Compositor, Inc. and Vercel, Inc. | Build only |
| remark-gfmTables and task lists in the observatory guide and the guides. | 4.0.1 | MIT | Copyright (c) Titus Wormer | Build only |
| yamlReads the front matter of each observatory chapter and guide. | 2.9.1 | ISC | Copyright Eemeli Aro | Build only |
| TypeScriptThe language the site and its physics are written in. | 5.9.3 | Apache License 2.0 | Copyright (c) Microsoft Corporation | Build only |
| VitestRuns the test suite on every change. | 4.1.10 | MIT | Copyright (c) 2021-Present VoidZero Inc. and Vitest contributors | Tests only |
The MIT License
Applies to three.js, Next.js, React, with the copyright lines given in the table above.
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
Left out on purpose
Sources that would have been easier to use, and why they are not here.
- The World Atlas of Artificial Night Sky Brightness (2016)
- Its data is licensed for non-commercial use only (CC BY-NC 4.0), and this site is a business. We built our own model from VIIRS radiance instead, and publish it in full on the sky brightness method page.
- Night-sky measurement sets licensed CC BY-NC, such as the Madrid SQM survey and REI-NSB Japan
- Tuning a commercial model on them is a commercial use, so they are excluded even as a private check. The model is fitted and tested on openly licensed and public-domain measurements only.
- AstroBin's equipment database
- AstroBin's terms ban scraping, and its API does not expose the equipment database. The gear catalogue is keyed by hand from manufacturer pages.
Last updated Counts computed at build time from the catalogue; the test count is dated