The Syndicate BattlecruiserCairngorm is where Nuclear Operatives spawn during Nuclear mode rounds. While we can't tell you what a battlecruiser actually is in this universe, we can tell you it contains all sorts of weapons and supplies for the Nuclear Operatives to use. We can also tell you that, despite all appearances, this ship can't actually move.
While there are a couple of ways to enter the Listening Post (including ones that do not involve the hand scanner), the only way to (re-)enter this ship is to use a syndie tele remote while standing on the Listening Post's telepad. Nuclear Operatives have these remotes on a table in the battlecruiser's armory, but regular crew members need to be more... creative to obtain one.
Speaking of which, if you do somehow manage to board this ship when it's not a Nuclear round, the nuclear bomb, some thermite charges, and a couple of gear closets will be missing. The other stuff here, such as the RPG, will still be around.
Most of the cruiser is also a sanctuary zone, so players can't take or add things from/to each other's inventories, and melee and ranged attacks have no effect, though they still consume ammo/charge.
In-game, this is all treated as one area, but it can be split up into a couple of rooms, each with different contents:
The Rooms of the Syndicate Battlecruiser
Cockpit
Not a real cockpit, the ship can't move. But you can coordinate operations from here.
A tape recorder. Play it to learn about your mission!
Atrium
Links up all the other rooms together with a lovely mountain range logo. Did you know what "Cairngorm" is a real word that describes a black-grey quartz?
The star of the show, the nuclear bomb, smack dab in the middle of the logo like it deserves to be.
A shooting range with clown bop bags, so you can safely try out your weapons...or indulge in your hatred of clowns. This area is not covered by the sanctuary zone, so your weapons will have full effect. Additionally, there is a special immovable ammo bag that lets you top off your weapon without wasting any of your own precious ammo.
A barricade dispenser, useful for setting up defenses around your delivery location.
A gear closet standing alone above the other gear closets containing a PDA with a built-in Detomatix cartridge, a box of flashbangs, a box of handcuffs, and multiple green pinpointers.
A pile of stinger and frag grenades. Both explode in a burst of shrapnel, giving everyone in the blast radius nasty brute damage and lodging shrapnel in their chests, causing further brute damage.
A flash/cell assembly for stunning people AND setting them on fire. But only once.
Syndicate Teleporter Remotes. If you want to try entering the station through the Listening Post, perhaps for a stealth infiltration (or because there wasn't enough room in the pods/subs for you), you absolutely need one!
A cigarette machine. Just like coffee, the nicotine in cigs is a mild stimulant too.
A water cooler and drink machine.
A marble "Mission Memorial" listing amount of times the Nuclear Operatives won and lost the round since about October 31st, 2020, the last time nuclear rounds stat tracking was reset. You can probably guess what the numbers look like.
A monkey in a retro-looking redspace suit named Oppenheimer. Keep your distance from him so he can't pick your pockets or shove you and take your weapon.
If this does happen, pull said monkey near the tables of the firing range in the armory section. This will take them out of the sanctuary zone, allowing you to take it from their inventory.
A firefighting closet. Because the guy who takes the Firebrand crate will inevitably set his/her teammates on fire, and when that happens, you'll be glad you took the extinguisher from here.
A pirate radio station, with similar equipment to the one radio hosts get to use except it quite clearly broadcasts you as a Syndicate station. Box has a sleeve with a bunch of records and some amusing tapes. The Nuclear Operative commander's ID is needed to access this room, primarily so that one rogue operative can't sabotage their by revealing the team's presence through the radio studio.
An office for the Nuclear Operative commander, accessible only by them. Comes complete with bookshelf, a sleepy pen, a pet (?) raven named Kuro, and amusing notes. But most importantly has a phone connected to the station phones and other places. Why not ring the radio studio or some other place and re-enact Zero Wang?