Data from NASA's All Sky Fireball Network indicate it was a meteor (rather than spacejunk).
20120101 03:15:36 UTC
Source
UFO over Phoenix / Tempe New Years 2011 to 2012
Green light streaks across Arizona night skyA streaking green light across the Arizona sky Saturday night created a stir among KOLD News 13 viewers and Facebook friends.Around 8:15 p.m., viewers called to ask about the light, wondering if it were a meteor, an asteroid or fireworks.Read more
A streaking green light across the Arizona sky Saturday night created a stir among KOLD News 13 viewers and Facebook friends.Around 8:15 p.m., viewers called to ask about the light, wondering if it were a meteor, an asteroid or fireworks.