A ship igniting its reverse thrusting procedure on approach to you would be easily visible. A ship accelerating away from you would be easily visible. But a ship that is not accelerating or decelerating would not be visible, except by any identifier lights shining on its hull. Ships leaving would be duller than ships arriving due to time dilation and distance shortening/lengthening causing shorter and longer light wave frequences respectively.

 I am the first one to admit my real space science knowledge is limited, but simple choices like everyone can or can not see lasers in the void of space can have a huge affect... both can be used to generate thrill in a plot line, but once a choice is established it must be maintained, even if latter you learn science says "no" as the players now know the reality you have created for them, it is the reality of the game. 

More imporatant in a setting with lots of small fighter style craft like Star Wars, BSG, or B5... but being able to see the firing solutions of ships might be imporant, like tracer rounds in heavy machine guns in real life.

So, maybe they would work on some kind of tracer laser light that is mixed in with other laser fire.

Also... Astrogation must need to take in to account hundreds or thousands of sources of gravity.  So... perhaps the telescopic tech in SF is FAR better then anything we have today.

The problem is the light years distance however.  So... if you see the ship on a space lane... its been gone from that point for years.   I don't see subspace tech working for some kind of detection attempt since the reflection would need to be carefully aimed back at the viewer.

So.... due to light sources... maybe... due to TIME... no.

How else would you justify the large time requirement of plotting a jump?

My assumptions where they while you are in void space grvity wells have some effect on you as you pass by them.  Your assumption is that while you are in void space it is entirely a different dimension totally detatched from the x,y, and z of real space.

In the concepts of space time being bendable and void space represents the distance between to points made closer by bending the real space reality.... I'm wondering if travelling through void space is really more like jumping from ripple to ripple in a real space planar wave created by all the gravity wells in between.  So in a sense each gravity well you pass by pulls you closer back into real space but your ship needs to resist that pull and basically jump from well to well... rather then being able to bend great real space distances together.  Just typing while thinking about it.  All this is still hinged on my assumption that gravity wells effect void space.

I suppose your saying that the greate the distance the greater the number of decimal points your calucations must go out to, but fundementally the nature of the calculations are the same.  In that method... you could establish that the time spent in void space could be calculated to a distance.  Like you could boil down a formula that says 1 second in void space equals 10000 AU... which might be useful on its own as it would enable a ship that is void jump capible to mke an emergency jump in any direction by say jumping for exactly one second.

I've been wondering if there could be able way to track or follow somebody making an emergency jump.  In trek... i think they can follow a warp signature or warp trail.  Star Wars they seem to be unable to follow you however as shown by the falcon's escapes from star destroyers.  How does Bobba Fett follow them?

Since void jumping is dependent upon how fast you go before being able to access the void, simply choosing to jump through the void at any time is not possible. You have to accelerate into the void and decelerate out of the void, which is why short void jumps are not possible. You need time to turn the ship or engines around to slow down. If you want a ship that can make short void jumps, you would have to double the number of engines on the ship and then some (to account for the extra mass). Thus void jumps cover long spaces, not small space. Thus, you also have to calculate exactly where you want to enter the void a distance so many AU's away from your starting point. In order to make those calculations, you have to start from a stopped position or else know exactly where you are going to be when you begin acceleration into the void. All of that is very difficult to calculate.

Yes, void jumping is no doubt very specific distances for very specific periods of time, but it is also not something that can be undertaken haphazardly. Any speculation about gravity wells is your own. It is not something indicated in KH and seems counter to the description in KH.

There are two things required here: locating the object, by the light reflected off it; and tracking it. The reflection is a function of the size and distance from the observer. Tracking a moving object is more difficult than it sounds.  Automation would be needed and some way of keeping focusing on a manuevering target. 

 I have read that the CIA/DIA examines foreign satellites with high powered telescopes located in the cargo bays of specially modified aircraft like the C-135. They fly in the upper atmosphere and photograph them. 

Subspace... its that SciFi fudgery in many many settings.  Does it use the void?  Is it something else outside of real space and possible the root of a different FTL travel method?  Some discovery of an energy wavelength that inately travels FTL (and considering 1 ly = 1 hour in subspace much much faster). 

Describing to myself and my players the sensor capabilities in the setting has left me with just telling them they have relatively short range radar, relatively short range energy sensors and visual.  But really when you boil down void jump calculations... visual isn't good enough.  

For radar to work at a distance of 30 hexes in ten minutes... i'm thinking it can't be radar as we know it.  Or maybe I'm wrong about that.

If you go to far with sensor tech, similar to gravity tech... you can radically change the setting's low-tech FTL space setting.

Maybe sensors has been discussed somewhere already or should be it's own topic.

I'm now thinking this... perhaps on the space lanes... the reason astrogation is so much easier... is because space buoys are installed along the route to communicate in subspace?  Still the need to accuruatly pin-point the target of a subspace transmission makes buoys not useful as you would need to know where they are?

Can you brodcast in subspace radially?  Like could there be a subspace radio station that can be heard at light years distances?  Real radio stations brocastig range is a function of power... maybe a subspace broadcast would have much less range but a series of buoys could be layed out one every ly along the space lane and they could daisy chain info.

How do they judge distances in real life and would that method not be sufficiant in SF?  

It seems like too some sort of alert system could exist based on the visible spectrum, telescope set to sweep in a pattern an area of space, recording images that the computer analysis and then alerts the crew/PC that a possible ship is present, this can then needs to be confirmed by a person.

Also open question on ship transponders... can the ship's id signal be picked up by others before exiting the void? Yes, no, maybe? I was thinking it might, then thought no... I suppose it depends on how fast the signal is going in relation to the vessel... like super fast jets that are already through the airspace by the time the radio signal for them is received?

I know it is probably a game convienance... but on a misjump... you always pop up at a planet by the rules.  I think that is where I get the idea that gravity wells reach into the void.... on a misjump you get pulled into a planet's gravity well, and that is why you pop up at a planet.

oh... how about this... gravity wells the exsist in the void itself so maybe you plop out in the real space equivlant of the other side of a void blackhole.  Rare and unpredictable... a tool for narative purposes.