A thermal camera is pretty common and easy technology these days
The heat signature of a crew compartment at 300K stands out against the cold background of space rather obviously unless you have a way to cool the aspect of your ship you are presenting to your enemy.
Just saying ships don't have thermal cameras is a bit belief suspender snapping.
My sensors are not one box or one dish (except on non-computer small craft, or the default all short range sensors associated with the bridge tonnage budget).
They are a whole series of emitters/detectors deployed all over the hull and used VLA-style. This gives a much higher resolution then a dish or singular camera, gives all-aspect rapid scanning, more datum points for achieving a firing solution, and helps ensure the ship will not go blind until it is largely wrecked.
Hull size is a factor in VLA resolution and thus chances.
The big sensors are multi-LS, multi-LM or AU in case of radio reception or astronomical objects. Their primary limitation is computing power, hence my detector ranges are driven more by computer model then TL directly.
So high end military ships, but also science/scout ships, get range advantage roughly analogous to the CT civilian-scout/military differences.
Without going into the whole homerule, lets start by thinking of the CT detection range, then the tracking range.
In my home rule, there are three levels of target state- Active, Passive, and Stealth/Doggo (shut down or special stealth systems).
If you emit a maneuver (grav or some form of reaction), a weapon, radio, or active sensors, you are active and can be detected at tracking ranges. This requires a sensor that can detect that system/emission type.
Active sensors gets you a better chance to detect passive and stealth/doggo ships.
If you are passive or stealth, you can run your systems at low power, keep passive systems on and can only be detected at detection ranges- but may be blind to other passive/stealth ships otherwise in range.
If you are doggo (shutting down all systems, the poor man's stealth), you are treated as a stealth target, but you have no passive systems beyond the short range one or special jury-rigs.
There is also detection vs. lock-on, with lock-on usually being handed off to the gunner and his fire control system local sensor.
Lock-on aka firing solution gives normal chances to hit, and allows for sensor operators to start getting tactical/scientific data on the locked object. Lose lock and you get the - 4 DM like switching targets, and the data stops coming.
By the way when you say particle detectors - which particles?
Neutrons, protons, electrons, alpha particles etc are all pretty easy to detect due to them ionising stuff - which is pretty much how the detector works.
Electromagnetic radiation waves/particles also interact with normal matter and so are relatively straightforward to detect.
Neutrinos and gravitational waves require huge expensive equipment to detect them - without some sort of handwavium science breakthrough, probably TL10+ gravitic based since the TL is about right.
As to neutrino sensors - if only the folks at DGP had taken a look at what a neutrino detector looks like here in the real world. It's yet another handwavium magic tech to have a neutrino sensor smaller than a thermal imaging camera on a telescope. Wave hands and link to gravitics, or damper tech, or whatever.
I'm assuming we are in higher tech and those primitive TL8 caveman particle tools have been superseded.
Again, no large tank or any of that, VLA across the whole hull.
Wide-spectrum, so yes all of those particles.
The patrol needs to track that pirate ion trail before it dissipates and goes cold, the scout contact ship needs to quickly determine if this inhabited planet has fission and/or fusion generation, the belter needs to find that big radioactives strike, the military sensor crew needs to ID the signature of the reactor, incoming PA fire and nuclear detonations from the unknown attacking ship, and the poor ore-haulers on the run to Mercury's mines need to know just how bad that solar flare is.
So the list would be
- Optical
- Thermal
- Radar
- Lidar
- EMF
- Mass/Grav
- Particle
The neutrino detection as noted before would be under Particle, densitometer under Mass/Grav and NAS under EMF. The latter two would be strictly higher tech and shorter range systems, not separate.
