Went of to google ,google is my friend
LV-426 was first introduced in the 1979 film Alien, though it is not named and is simply referred to as a "planetoid" or "ball". In the 1986 sequel Aliens, LV-426 is named. On the timeline of the official viral website for Weyland Industries, as part of the promotion for the film Prometheus, the planet's name appears on the timeline page, as officially "Acheron LV-426" bringing both names together. The planet was thought to appear in the film, but instead, the planet LV-223 was used. --Alien versus Predator Wiki > Archeron LV-426
Hey you found my T-shirt !!!! I got that.
Nice sleuthing - Alien indeed is one of my all time favourite films.
In fact when I first joined GGJJ forums I had a signature on my profile that said "Do Weyland-Yutani provide maternity leave?".
I was also going to have my name as Nostromo instead of EC, But I thought EC may get people quizzing me about it's origins so stayed with that.
Nostromo is the spacecraft which featured in the original Alien film.