You frequently mention that you warp into a new wormhole and "throw your probes out of the system" so people can't detect the scanning. I was wondering what that means and how I do it.Good question! To explain it properly, first you need to understand the context, and that is hunting in wspace. You want to find targets, and sometimes scan down sigs, without them noticing you are there. If they know you are there, they'll POS up or else swap into nasty pointy ships. I feel we need some humor to set the mood here:
The goal of the hunter is to see, but not be seen. So, how does one go about stealthily looking for targets in a wspace system?
To see people in wspace, you can't use Local. (Actually, you can see them via Local if they do talk, but of course the first rule of wspace club is: nobody talks in Local.) You can only see someone who is uncloaked. You'll see him on overview if he is on grid with you, or can see his ship using dscan. Any time an uncloaked ship is within 14.3 AU of you, you'll see it when you dscan. The same is true of scan probes: you can see them if they are within 14.3 AU. Seeing scan probes is one of the more common ways to know someone is around, although not what ship it is.
To avoid your ship being seen, the rule is "stay cloaked all the time". This means that you hunt in a ship with a stealth cloak, and you use that cloak at pretty much all times except when you are on-grid with a target and attempting to kill it.
There are two main exceptions to "stay cloaked all the time". One is that you have to uncloak briefly when you drop gate cloak after entering a system. This will only appear to you as a second, and you cannot be locked once cloaked (as you see it). However, from the point of view of other people on grid, and those watching on dscan, you are visible for about 10 seconds. So they will have a fair chance to see you.
Here's what you should do routinely upon entering a system. You should always dscan upon entering a system in wspace, while still holding gate cloak. If you see ships and a tower, they are probably at the tower. But you can use narrow-beam dscan to check that out. If you do find a ship out in space, congrats. You're in a fairly rare situation. Go get 'im!
Once you've dscanned to check things out, you want to move off the wormhole and cloak as soon as possible. Here's how to do that. Right click on the wormhole and select Orbit at some distance. 20km is good, but mix it up with other distances. Immediately upon doing this, your ship will start moving, and it will lose its gate cloak. Click your microwarpdrive to get it going, then cloak as soon as possible. (You can't cloak if you are within 2000m of anything, most particularly the wormhole.) Usually you can cloak immediately.
Once you are orbiting a wormhole cloaked at 15, 20, 25 or 30km (be random), you are very unlikely to be decloaked by anyone. The volume is quite large. Don't forget to bookmark the wormhole, so you can get back to it. (Here's my article on the naming conventions I use for bookmarks.)
Another exception to "stay cloaked all the time" is that you must be uncloaked to fire probes. Often you can do this as you burn off the wormhole just after you entered. I combine the two actions unless I see a ship on scan; in that case I usually don't, since hiding your probes does take a bit of time and it also will take your attention away from the overview. But if you see no ships, you can save time by launching probes. Do the same moves as I just discussed above, except that just before you cloak, fire your probes.
What about the case where there is a ship on scan? To avoid being seen, you should look for a place to fire probes that is outside of the range of any known target. This is easier in larger systems; in general outer planets are good for this. Warp around to various planets and see if there is one out of dscan of any ship. (How do you know? Dscan: if you can't see an uncloaked ship, it cannot see you.) Sometimes you'll just have to fire probes in scan range of a tower, or ships that might be manned, or even known manned ships. If so, do it and recloak as soon as possible.
But what about your scan probes? Scan probes are visible on grid when you first deploy them. After that, they are detectable only via dscan, and can be detected at all times except when they are moving. (Scan probes cannot cloak.) Even if nobody saw your ship when you uncloaked to fire probes, firing probes still leaves them sitting out where you fired them. Anyone coming within 14.3 AU can dscan and see them. Seeing scan probes is plenty of warning for anyone with any sense to realize that they are not alone in the system.
Because scan probes will give away your presence, you want to move them immediately to a location where they cannot be seen. How is this possible? It's possible if each scan probe is more than 14.3 AU away from every point in the system that anyone could be. Since wormholes can appear as far as 8 AU from a planet, you want to move your probes to at least 24 AU away from any planet.
Here's how to hide your probes. You move them just like you do when scanning, except that here you are trying to put the probes where there is nothing rather than something. Bring up the system map, then set your scanning distance to 16 AU. Now move the probes out of the system, such that all of bubbles showing the probes' coverage are at least 8 AU from all planets. (8 AU is half of the 16 AU bubble size; you can eyeball this distance by comparing to the bubble size.)
Press the "Analyze" button; the probes will warp to their assigned locations way outside the system. (The scan itself will run, and of course never have a result since nothing can be out that far.) This process of moving your probes away from where anyone can be to hide them is referred to colorfully as "throwing your probes out of the system". (Anyway, I say it, and I got it from Penny. Perhaps she is original.)
Note that it is not possible to scan things down and have scan probes remain hidden. So you won't be able to find a gas site, for example, with a Venture in it without the Venture being able to see the probes on dscan. You can attempt to minimize the amount of time that the probes are visible to a target. But that's a different article. An article which Penny has already written.