I say 5, for playability reasons.[/quote]
Some numbers: Update: these are all diameters, not radii, so if you’re looking for “how far away”, divide by 2.
Reality bubble is roughly 3 map tiles around you.
Presuming your vision is unimpaired, overmap scouting range (the current mechanic that usually marks the tile on your map: Lab satellite downloads can do the job too) is, at base, 10 tiles. This is more or less the 5-tile range desired.
Binoculars/a rifle scope (on or off a weapon), or the Scout trait doubles that to 20. /2 = 10 tiles.
Both an optic AND the Scout trait adds up to a 25-tile mapping range.
If you have Avian Eyes, you get an additional five tiles. (Bug: that doesn’t apply if you’ve no optics or Scout, but I’ll be filing a PR shortly to fix that.) Thus the absolute maximum range at which one can currently tell there’s a LMOE around is 30 map tiles away. That said, you’d have to be a post-thresh Bird being with both recon training/experience and proper optics to get that. 10-20 tiles is more realistic.
Bear in mind that some terrain is tougher to “see”/map through; in particular, forests can severely shorten your ability to map.
[hr]
Dunno how many folks have had to manually go coven-hunting in TES:Daggerfall, but having spent quite a lot of time looking even when given directions and map coordinates, I have no desire to inflict that experience on others.