What we hold, why, and how to have it removed.
| Your photograph | the file as uploaded |
| Its metadata | camera make and model, lens, capture time and UTC offset, exposure, ISO, focal length, image size, and GPS if the file contains it |
| Coordinates you give | latitude, longitude, optional height, and how they were obtained — your device, typed by you, or the centre of a town you named |
| Time zone | your browser's zone and offset, and the difference between your clock and ours |
| Email address | optional. Only if you choose to give one, and only used to send you a copy of the write-up once it is ready |
| Technical | your browser's user-agent string, a random session token stored in a cookie, and a random contributor id stored in your browser |
The study measures how accurately a position can be recovered from a photograph of the Moon against the stars. That requires knowing where the photograph was actually taken, so our answer can be scored against the truth. Without your coordinates and an accurate capture time the photograph has no scientific value.
Your coordinates together with a capture time are personal data: they record where you were at a particular moment. You are welcome to round them: the method itself is only accurate to about 100 km, so a few hundred metres is already far finer than anything we can measure. A submission is screened by asking whether our answer falls within 500 km of what you claimed, so even a town centre passes comfortably.
On your first visit your browser generates a random id and keeps it in local storage. It lets us see that several photographs came from the same contributor — which matters scientifically, because a second frame on a different night with the Moon at a different height is the most useful thing you can send us, and we need to know it is a second one.
It is a random string. It is not derived from your device, your network or anything about you, we do not link it to any other dataset, and because your own browser creates it we treat it as a hint rather than proof of who sent something. Clearing your browser's site data removes it; you will then appear as a new contributor, and nothing else is affected. You can see yours on your result page.
The instant check on the upload page stores the photograph, the verdict and the time, even when the verdict is negative — and most are. This is deliberate: frames that fail are the ones the measurement needs to get better at, and in our own sessions most frames fail for want of stars. If you would rather a checked frame were not kept, do not upload it.
Photographs and their measurements are research data and are kept indefinitely, including frames that failed to solve — those are what the method gets improved against. Email addresses are deleted once the write-up has been sent.
You can ask us for a copy of what we hold about you, or ask us to delete it, and we will do so. Your result link identifies your contribution; keep it if you may want to exercise either.
Your results are reachable only from the browser you uploaded with, through its session cookie. Nothing about your contribution travels in a web address, so there is no link that could be forwarded, left in a browser history, or pasted somewhere public and still work. The trade is that a result cannot be opened on another device — if you clear your site data or sign out, tell us the approximate date and place and we will find your contribution from that.
Write to pavel@devnull.ae and say what you would like done. If you still have your result link, include it — it is the quickest way for us to find your photographs.
| Organisation | DevNull FZCO, United Arab Emirates |
| Contact | pavel@devnull.ae |
One address for everything: questions about the study, a copy of what we hold, deletion, or withdrawing an email address you gave us.