High Guard (old) p48: Primitive and Advance Spacecraft: Stealth Jump
"Normally a ship that emerges into real space will be automatically detected in it emerges within the 'minimal' range of the sensor."
"detecting a ship equiped with a stealth drive emerging into real space requires a formidable (14+) Computer (sensors) check"
Pirates of Drinax (book 1) p109
"Picking up on the neutrino emissions requires a Difficult (10+) Electronics (sensors) check (INT)"
"A very difficult (12+) Astrogation check (INT) lets an astrogator guess the likeliest destination of a jumping ship based on neutrino emissions and the shape of the inflating hydrogen bubble"
From this I conjecture that:
Detection of a jump is automatic.
A sensors check is needed to get the magnitude of the jump bubble and therefor the distance jumped, based on the size of the ship.
Astrogation is able to then add the direction, based on the pattern of emissions and star alignments.