How far do Ship sensors work to?

[Vidgar]

This table below show sensor work (to varying degree) out to 50,000km.
A ship accelerating at 1G (9.08655m/s2 to travel 1 AU (149,600,000km) will travel for 68.7hours and at the point where the ship starts to de-accelerates the ship is travel at 4,321,202 km/h and covers 50,000km in 41.6 seconds.
1) My numbers maybe in error.
2) That's not a lot of time to nig a ship around object.
3) Planets, have known plotted orbits.

So how far out can Far Trader A see and identify a object as Far Trader B?

 

[Vormaerin]

Sensors can detect objects at Distant range, but the information available is limited. So the question is whether or not Far Trader B is running its transponder, as it is legally obligated to do. If it is not, then it is unlikely that a civilian grade sensor suite would get more than "there's something over there that's about the right size to maybe be a ship" at greater than 25k. If the transponder is on, then it'll know what the ship claiming to be at well beyond 50k. (I think Distant goes out to 300k?).

 

[MonsterX]

I think the fact that 50000+ is left open is deliberate. Oumuamua is about 100m long, so comparable to a 100000 ton Traveller ship, and it was detected even though its closest approach to Earth was 24 million km. Traveller spacecraft don't have fusion torches, so they won't be automatically detectable instantly from everywhere but they are visible and also will have all kinds of emissions. So it is possible to detect ships really, really far away in principle.

However, I think operationally, the real question is usually whether you can notice, appropriately identify, and perhaps get a target lock on, the emissions your scanners are picking up, which is what the rolls and range bands are gauged around. You might be able to get some information about ship sized objects millions of kms away through observing them over extended periods - so, for example, if you have scouts which have found the enemy, tracking their progress could be done much more easily than finding them in the first place.

 

[Condottiere]

You're looking for something unusual, and being able to recognize it's unusualness, if not identify it.

Combination of unusualness might be greater than it's parts, so the recognition, not necessarily detection, might be possible much further afield.

 

[Vormaerin]

What can be detected with the cheapass sensors (-2 DRM!) on a private starship and what can be detected by fancy scientific instruments are not the same thing. Pan STARRS is a pretty specialized tool for just that purpose. Also, time frame? IIRC, it took about a month of data processing before anyone noticed that Oumuamua was there. And, then they kept having to revise the conclusions on size and shape.

Anyway, the rules in High Guard state that Distant covers up to 300,000km. You can, in theory, make sensor checks at Very Distant (up to 5 million km). But that's a Formidable Sensors test (14+) BEFORE you apply the -2 for civilian sensors. Anything beyond Very Distant is equally difficult, but even more limited as to what can be determined (jump flash, object volume to the nearest 10k dtons). As a practical matter, a Far Trader's not gonna do it.

Those distances are for space stations and fancy scout ships with specialized gear.

 

[Condottiere]

And then you have an experienced sensor operator, who can make informed guestimates.

 

[MonkeyX]

Additional question, how long does that information take to get back to the ship?

 

[Condottiere]

Lightspeed.

 

[Rel Fexive]

A light second is about 300,000 km, so those range bands fall within that time frame. High Guard's top end is that distance, so a second's delay for visual and two for things like radar/lidar.

 

[Vormaerin]

The real question is how close do you have to be to tell the difference between these two things?

 

[Condottiere]

One's a large dick, the other's populated by them.

 

[MonsterX]

The real question is how close do you have to be to tell the difference between these two things?

View attachment 1488

There isn't actually a difference. You have just figured out what Oumuamua really is; you should give Avi Loeb a call.

 

[gilthy]

It depends on the type of sensors Far Trader A has (and has running, and whether they're using Actov or Passive Radar or Lidar, if they have the choice). And the distance, of course.

If we go by the "default" Far Trader A2, it has Civilian Grade sensors installed, which offer Lidar and Radar (with a -2 DM on the Electronics(sensor) check).

At some point, "Distant" will (with Active Radar/Lidar) get a "ping" back, but at 300k KM, that will be where it was 1 second ago (due to light speed limitations). See the tables on page 160 (in the 2022 core book) for what detail can be spotted, and at what range.

 

[Jame Rowe]

The real question is how close do you have to be to tell the difference between these two things?

View attachment 1488

One's a rock. The other's a refined rock filled with EM radiation.

 

[tytalan]

So HighGuard 2022 changes the range bands to the following

Adjacent. 1km or less
Close. 1-10 km
short. 11-1250 km
Medium. 1251-10000 km
Long. 10001-25000 km
Very Long 25001-50000 km
Distant 50001- 300000 km
Very Distant 300001-5000000 km
Far over 5000000 km

Jump can be detected all the way thru Far except if it’s a stealth jump drive which is undetected at Far.

 

[AnotherDilbert]

The detail is on p160 of the Core book:


Distant range will get you a sensor-blip, nothing more. With some basic stealth you will probably see nothing.

Ships that want to be seen with transponders and active sensors will be seen by the active emissions that are probably spoofable. That "Free Trader" might be a corsair or SDB.

At Long range you can start to get some actual information about the ship, or Very Long with an Extension Net.

As Vormaerin already said, above a light-second (300 000 km), civilians won't see a thing unless by a fluke.

 

[Rel Fexive]

While we are on this subject, I continue to be confused by exactly what ranges a stealth jump are or are not detected at. The text, which isn't terribly clear, says:

"Normally, a ship that emerges into real space is automatically detected if it emerges within the minimum detail range of the sensor. However, detecting a ship equipped with a stealth drive emerging into real space requires a Formidable (14+) Electronics (sensors) check (1D rounds, INT or EDU) if it is within the ‘limited’ detail range of the sensors or automatically fails if outside the minimum detail range."

So I assume "minimum" should be "minimal" here - it's helpful the table is just above!

It says a normal j-drive is always detected at "minimal" or better - and we must always be talking about the EM range, since this should always be a passive detection of the energies released by a jump arrival.

The way I read it, a stealth jump is never detected at "minimal" and requires that Formidable roll at "limited". But it doesn't mention the "full" range, so either it still requires the roll at "full" or the ship is still automatically detected at "full" - which is it?

 

[tytalan]

While we are on this subject, I continue to be confused by exactly what ranges a stealth jump are or are not detected at. The text, which isn't terribly clear, says:

"Normally, a ship that emerges into real space is automatically detected if it emerges within the minimum detail range of the sensor. However, detecting a ship equipped with a stealth drive emerging into real space requires a Formidable (14+) Electronics (sensors) check (1D rounds, INT or EDU) if it is within the ‘limited’ detail range of the sensors or automatically fails if outside the minimum detail range."

So I assume "minimum" should be "minimal" here - it's helpful the table is just above!

It says a normal j-drive is always detected at "minimal" or better - and we must always be talking about the EM range, since this should always be a passive detection of the energies released by a jump arrival.

The way I read it, a stealth jump is never detected at "minimal" and requires that Formidable roll at "limited". But it doesn't mention the "full" range, so either it still requires the roll at "full" or the ship is still automatically detected at "full" - which is i

As I posted above these are what the range bands are changed to in HighGuard 2022 which superseded pg 160 CRB
So HighGuard 2022 changes the range bands to the following

Adjacent. 1km or less
Close. 1-10 km
short. 11-1250 km
Medium. 1251-10000 km
Long. 10001-25000 km
Very Long 25001-50000 km
Distant 50001- 300000 km
Very Distant 300001-5000000 km
Far over 5000000 km

Jump can be detected all the way thru Far except if it’s a stealth jump drive which is undetected at Far. As you can see they added Very Distant and Far. At Far the only thing you can detect Is the jump signature and not even that if it’s a stealth ship. At Very Distant you can detect any Jump signature. This should answer your questions

 

[Rel Fexive]

The description of the stealth jump mechanics is also from High Guard 2022 and it refers to the level of sensor detail required to detect a jump, stealthed or otherwise, not the range bands. So the addition of further range bands makes no difference, and the "sensor target" table from the core book posted above has not been supplanted by a different table in HG2022.

 

[Vormaerin]

The way I read it, a stealth jump is never detected at "minimal" and requires that Formidable roll at "limited". But it doesn't mention the "full" range, so either it still requires the roll at "full" or the ship is still automatically detected at "full" - which is it?

If you jump within Full sensor range of another ship, they detect it even with the "stealth jump" improvement.