I use jump flash at both ends (and visible from inside as well!) so for me the stealth aspect is simply to put one's self at a point where one's flash is not going to be seen... but then, that means, in most TL 8+ systems, far outside the habited areas... and thus defeating surprise.
And, by TL12, gravimetrics exist which can detect jump-transitions due to changes in gravitic potential sweeping across a pair of sensors. (Use 4 in a tetrahedron, and you get 3D triangulation...) Mind you, you'd need to be looking, but that's not that hard...
Jump flash on entry is canon; it exists in TNE's Regency Source Book. Wherein it also says it is readable (rather hard, but readable) for which hex is targeted.
And, by TL12, gravimetrics exist which can detect jump-transitions due to changes in gravitic potential sweeping across a pair of sensors. (Use 4 in a tetrahedron, and you get 3D triangulation...) Mind you, you'd need to be looking, but that's not that hard...
Jump flash on entry is canon; it exists in TNE's Regency Source Book. Wherein it also says it is readable (rather hard, but readable) for which hex is targeted.