Glad to see this getting exposure on HN. I gave a PyCon keynote [1] last year about how this was done. I've also put the image online in my own viewer [2], which has a few additional features: it encodes the viewing location in the URL and it allows for multi-pane synchronized views [3]. (Please be nice to my server.) I'm happy to answer questions here or on Twitter (@erdmann).

[1] https://www.youtube.com/watch?v=z_hm5oX7ZlE

[2] https://hyper-resolution.org/Nightwatch5

[3] https://hyper-resolution.org/view.html?mode=trumpet&pointer=...