The real question is: why do you want to get THAT close.
This program, though reasonably normal at times, seems to have a strong affinity to classes belonging to the Cat 2.0 program. Questerius 2.7 will break down on occasion, resulting in garbage and nonsense messages whenever it occurs. Usually a hard reboot or pulling the plug solves the problem when that happens.
It depends on your stealth rating versus the enemy's perception. Aux power and sensor skill increase perception. The most stealth you can probably achieve with a very specialized build is about 4978.5 (that's just with consoles, skills, sci ship aux at 130, and reman/romulan deflector). That would mean a ship would have to have no more than 5003.5 perception or they would detect you at 0.5 km. Even an escort could detect you at that distance with minimal aux power. I'm not sure why you would be interested in getting that close since nothing requires you to be any closer than 3 km from the target. A science ship with maxed out aux, a full set of VR sensor probes, 9 ranks in sensors, and Jem'Hadar deflector would detect you at over 8 km.
Comments
You might want to read this maintenance thread on stealth and detection.
Regarding Stealth Detection