My players are about to begin a new mission where they have to track down a specific space pirate ship (the last known location of a dangerous artifact). I have a few ideas about how to go about this, but I wanted to throw this out to the community to see if there were other options that I was overlooking.

They will be working in partnership with the Imperial Navy, which hunts pirates as part of their standard duties, so procedures have to be limited to what would be available to the Navy: they can't automatically know how to find pirates (much less specific pirates), because if they could, they would have wiped them out long ago!

My thinking was that the I.N. would be employing decoy ships along major shipping routes to tempt pirates into attacking, only to find that the decoys are filled with troopers (they should ideally be called 'marines', but we can't use use that term for anything other than Astartes in 40K), with an I.N. vessel shadowing the decoy at the limits of auger range. This is 'catch as catch can', with no control over if or when an attack occurs or which pirate ship attacks, making it both very time-consuming and unlikely that the Acolytes will find the one ship they are looking for by this method.

Pirates should theoretically have some kind of secret base where they can meet, repair their ships, and engage in trade ( a la Tortuga in the days of the Spanish Main). This would probably be a better place to intercept the ship they are looking for, but it's location must be secret (otherwise the I.N would have purged it already).

So, my thinking was that the PCs would be stationed aboard the decoy ship, waiting weeks for an attack to occur, then taking some pirate command crew prisoner; the party's Psyker would then Mind Scan the pirates to locate their secret base, and go there undercover and wait (weeks, months?) for the specific ship they are looking for to put into port.

Workable, but extremely inefficient and time-consuming. So, my question is, is there a better/simpler/faster way to locate a specific pirate ship, that I am overlooking?

The waiting weeks sounds like it might prove very boring, I'd make sure that they have something to do in the mean time stop a mutiny kill a mutant cult in the holds or something.

The pirates would likely have a general area of operation, unless they have a warp drive, but that'd be a very large ship indeed. In all the decoy thing sounds like the best idea.

While the decoy ship is traveling trough the warp to the sector where the pirates have been most active, there's a slight fluctuation on teh ship's Geller field. A crewman near the PC's becomes possessed by a Daemon. It speaks:

"Looking forrr Somethiiingg? I can help you find the ship you see-seek! Ooh yes! Nothinggg is hidden in the warp.

If i lead you to the pirate vessel- what will you give-give me in rreturnnn?"

Now no purehearted, self-respecting, Emperor-fearing Imperial citizen would concider bartering with daemons to track down a pirate ship. On the other hand these are acolytes on a mission...

This might not really be what you are looking for, but it could be used to make the search for the ship a bit more interesting.

While the decoy ship is traveling trough the warp to the sector where the pirates have been most active, there's a slight fluctuation on teh ship's Geller field. A crewman near the PC's becomes possessed by a Daemon. It speaks:

"Looking forrr Somethiiingg? I can help you find the ship you see-seek! Ooh yes! Nothinggg is hidden in the warp.

If i lead you to the pirate vessel- what will you give-give me in rreturnnn?"

Now no purehearted, self-respecting, Emperor-fearing Imperial citizen would concider bartering with daemons to track down a pirate ship. On the other hand these are acolytes on a mission...

This might not really be what you are looking for, but it could be used to make the search for the ship a bit more interesting.

I ran a 'de-Haarlocked' version of Damned Cities ; when the PCs found the Daemon in the Mirror, they did exactly this , agreeing to free it in exchange for information (which is how they found out that the artifact was last seen aboard this particular pirate ship in the first place)...

In that case, the pirates (lacking a warp drive, ofc) could simply have been warned about their arrival and are now actively trying to kill them, by turning the system in question into a death trap, with thruster-propelled ballstic asteroids and other shehanigans.

I'm thinking space pirate ships would pretty much have to have warp drives; otherwise it would take weeks or months for them to get away from the scene of their attacks.

That seems like an awfully inefficient way of tracking down pirates. My perception of the Inquisition is one of their specialties is infiltrating those types of organizations. Not necessarily always to bring them down from the inside, but for a variety of purposes. Tracking down particularly troubling artefacts would fall under that. I would imagine there would be better ways of finding their quarry than such a resource intensive fishing trip. Even powerful Inquisitors would probably have a hard time keeping so many resources tied up indefinitely, on the hope that they just happen to get attacked by not only pirates, but the right pirate ship. Plus, how many wrong pirates can attack the fleet before word gets out? before one gets away, or sends an astropathic warning?

Not that's in an impossible way of doing it, but I might try to encourage them to try to find some other method. Perhaps a seyance, or putting a reward out for a particular crew member on that ship. Maybe some rogue traders have some information for sale. Some Inquisitor somewhere has to have at least ears on a pirate crew, they are pirates after all. Many of them might have a code of criminals, but that's the end of the line for a lot of them. Lots would probably betray their mother for an 8ball of spook. Just a thought.

Depends on the type of pirate as well of course. Some might effectively be 'classic' Sci Fi pirates, not warp capable or only very limited preprogrammed warp jumps and prey on intersystem ships.

Alternatively the pirates might have a rouge Navigator or even xenos tech to allow them to be fully warp capable.

The first pirate probably just relies on not being enough of a threat to attract the attention of the Imperial Authorities while the second relies on actively evading the Imperial Authorities.

Finally you might also have certain merchants who indulge in piracy occasionally and rely on not being found out.

In terms of finding the pirates it would be a case of:

1.Identifying who the pirates are

2.ambushing them at a trading post

3.laying bait.

4.using divination or some other process of deduction to work out where they will be. Running a star ship is EXPENSIVE fuel food oxygen. The pirates probably only have access to a couple of 'watering' holes,be they natural astronomical phenomenon or space stations. Also ships don't exit warp too often. There are probably only a few places which pirate will routinely be able to rely on encountering a ship worth plundering.

I'm thinking space pirate ships would pretty much have to have warp drives; otherwise it would take weeks or months for them to get away from the scene of their attacks.

Chaos raiders do. Normal pirates don't. They stay in system and hit freighters on the fringes.

I'm thinking space pirate ships would pretty much have to have warp drives; otherwise it would take weeks or months for them to get away from the scene of their attacks.

Chaos raiders do. Normal pirates don't. They stay in system and hit freighters on the fringes.

There's various levels of pirate. Sure, Chaos Raiders have warp drives. But they don't have a monopoly on illicit human warp travel. There's plenty of illegal warp travel going on as well by people who aren't Chaos worshippers. Sure, it's not that hard for a non-Chaos pirate to slide into the embrace of Chaos, but there are plenty who haven't.

Admittedly, the non-Chaos warp capable illegals are mostly organized crime and smugglers - or Rogue Traders who crossed the line without crossing over to Chaos, and were officially stripped of their Warrants, but managed to get some of their ships out.

Yep, far as I'm reading warp capable pirate groups are part of the organised crime structure, which provides further venues of investigation, or, -trouble- for the players. I'll toss in the Kasballica here. They may be what OP is looking for.

bare in mind that you can technically use warp drives without a Navigator. The problem is that you need to preprogram the jump into a highly complicated cogitation system and you can't go nearly as far.