Euclid's C-Finder

 is a weapon in Fallout: New Vegas.

Characteristics
The raw power of the sun, contained in an easy-to-carry package! Just point the handheld rangefinder at the bad guys, and pull the trigger! The Archimedes II orbital laser will strike down and reduce foes to ashes.

In order to use Euclid's C-Finder the player character must complete the That Lucky Old Sun quest and choose to direct power to Archimedes II at the end of the quest. The weapon can only be used once every 24-hours because of the recharge time of the lasers. If the player has already completed that quest without directing the power to Archimedes II, the C-Finder cannot be activated.

Euclid's C-Finder is not a weapon in its own right, but rather a targeting device or "range finder" for the Archimedes II orbital laser platform. As such Euclid's C-Finder inflicts 0 damage on a direct hit to a target, with all the damage coming from the blast caused by the Archimedes II orbital laser strike. This also makes Euclid's C-Finder inoperable as a weapon when fired indoors.

Firing Euclid's C-Finder will result in a small delay and an animated sequence on Euclid's C-Finder's display, before the impact of the orbital laser strikes the ground. This delay means that Euclid's C-Finder can be repositioned for a new target before the laser strikes.

Location
In Freeside, outside of Mick & Ralph's, the player character can find Max during the day. Max thinks the weapon is actually just a toy, as it is reminescent of the popular 1950s-60s toy laser guns for children. The player character can pay Max 1000 bottle caps, or 20 bottle caps with a barter skill of 45 or more, for his "toy gun" Euclid's C-Finder. Otherwise the player character can wait until Max goes to bed, usually after 9pm, then pickpocket him to get the gun with no karma loss.

Bugs

 * It is possible Euclid's C-Finder may re-spawn multiple times on Max. If you do not have the gun in your inventory and return to Freeside some time after acquiring it, Max will have another Euclid's C-Finder . This will also result in additional ARCHII Charges added each day for each Euclid's C-Finder in the player characters inventory.
 * If the player character has the Heave Ho! perk, firing Euclid's C-Finder may freeze the game. To fix this a PC user can remove the perk using console commands, this will allow the player to fire the weapon without crashing.
 * When trying to fire, the targeting laser may repeatedly play its animation without the laser firing. To fix, save the game with the gun drawn and firing and then quit the game completely back to the desktop/reset console. Restart, reload, and wait for the firing animation to complete. Ensuring to save far enough away from the target to not be hit, but close enough that the animation is still visible and playing.
 * Sometimes the gun will not get any ammo after activating Archimedes II, or it will fire a few times and then not get any more ammunition. To fix, save the game and the quit to the desktop/reset console. Reload the saved game and then after some time the charges will spawn as normal.
 * Sometimes Euclid's C-Finder will not fire at all, only the lasers will be seen. However, the gun will also go off at a random time after this.
 * The game seems to register kills with Euclid's C-Finder as "unarmed" kills as evidenced by getting the Beautiful Beatdown perk while using it.
 * Obtaining Euclid's C-Finder before completing or at least initiating the quest I Could Make You Care, could bug the quest. See the page quest page for details.
 * If aimed at a lake or body of water, there will be a bright flash of light, but no laser.
 * Euclid's C-Finder may disappear from the player characters inventory after being caught stealing from the Silver Rush in Freeside, even after killing them.
 * Sometimes after activating Archimedes II the C-finder will have two charges, the first will fire normally, however the second will charge but will not fire. You will see the targeting laser animation (three lasers that circle the target and meet in the middle) but there will be no damage and as added downside the animation will loop indefinitly every 5-10 seconds following your crosshairs no matter what weapon you have equipped. The only known fix is to reload the last save, but this will however not fix the C-finder from firing blanks, just the targeting laser loop.

Behind the scenes

 * Euclid was a famous Greek mathematician, known as the originator of many basic geometric and mathematical principles. Euclidean geometry and Euclid's algorithm for calculating the greatest common factor of two integers are both named for him.
 * The name Euclid's C-Finder, and the graphics it shows the player while it is operating, are a reference to using Euclidean geometry to find the third point, C, of a triangle, given points A and B, and distances BC and AC. In this example B is the player's position on the ground, A is the position of the Archimedes II satellite, and C is the position of the target. The satellite gets distance BC from Euclid's C-Finder (which is described as a "handheld rangefinder", in the terminal notes at HELIOS One), and knows AC, one assumes, from radar height measurement. In practice, the satellite would also need to be able to determine the direction Euclid's C-Finder is pointing. Presumably, Euclid's C-Finder can only measure basic compass heading and range, leaving the satellite to calculate the target's elevation.

Gallery
Алгоритм Эвклида