Stalker: Call of Pripyat → Quests → Night Hunt (for the Chimera)
Once you've completed the task, you'll receive money (as usual) from Zveroboy and St. John's Wort's personal shotgun.
It's simply brutally durable. Also, make sure you have plenty of first aid kits and bandages, and drink an energy drink beforehand—you'll be running around in circles for a while. The main thing is to stay in sight of the enemy, and that's difficult, given the Chimera's incredible jumping ability.
Travel to the south of the map and wait for nightfall (two or three hours after midnight will do). You can try setting up an ambush by climbing up the ladder to the top of the cistern. But that won't work; you need to go down and stand in the center of the area. The Chimera will gallop up from the east. Get a "Rebounder" or something similar ready, preferably a modified one, and preferably 50-60 rounds.
See also:
Meteorite landing. Event in Terraria