Was the alien planet LV-246 or LV-426?

In the movie Alien and its sequels, the moon on which the crew of the Nostromo landed was called "LV-426."

A name for the moon was not actually spoken in the first movie, Alien, but it was acknowledged verbally as "LV-426" in the second movie, Aliens. It was also referred to in the script as "Acheron," which is a name from Greek mythology that means "stream of woe." While referred to in Alien as a "planetoid," Acheron/LV-426 is the second of three moons orbiting the planet Calpamos, which is the fifth planet from the star Gliese 86.

LV-426 was featured heavily in both Alien and Aliens, while the planet in Alien 3 was Fiorina 161, nicknamed "Fury 161."

Alien Resurrection took place entirely within spaceships. The new prequel Prometheus takes place largely on the moon "LV-223," which is a satellite of another planet in the same solar system as LV-426. While all of these moons and planets are fictional, Gliese 86 is a real K-type dwarf star in the Zeta Reticuli star system.