As for v2.5, we only get white/yellow selection circles around targeted UFOs on the geoscape.
What would be handy, even if the player comes to learn those ranges by experience, is to have the weapon ranges and why not the sensor range of any researched UFO that is displayed on the geoscape, or at least, of the one being selected or targeted by a selected PHALANX craft.

It would be better if this technical knowledge would come only after a given UFO and alien technology are researched, of course.

Any UFO type could be attached one, two or three flags when it's displayed on the geoscape:

* UFO is researched and PBW is researched -> draw red PBW range circle
* UFO is researched and Alien Launcher is researched -> draw red alien missile range circle
* UFO is researched and Alien Detection is researched -> draw white alien detection range circle
(perhaps the sensor range depends on the UFO type)