In Alien: Covenant the ship was heading to Origae-6.
After the neutrino blast and receiving the signal from Elizabeth Shaw the crew found out that near their position was a planet that was substantially closer and more habitable than Origae-6.
In the dialog between crew members it was stated that it took years to search for the habitable planet. On the other hand the Engineers' Planet was in the database the whole time.
Why wasn't this planet the original destination of Covenant?
The crew of the Covenant discuss this very point in the film's Official Novelisation. In short, they don't know either.
“Everything points to a high likelihood of a living biosphere. Leastwise, the necessary markers are all there.” His attention shifted to Daniels. “Everything I see suggests a world that exceeds the company’s and your most optimistic projections for Origae-6.” “You’re sure of all of this?” Looking skeptical, she studied the data on his console.
He grunted. “As sure as Mother’s sensors can be. And we’ve got a damn sight better view of it from here than anyone on Earth did of Origae-6.” The implication of this information escaped no one.
“How did we miss it?” she demanded. “We scanned every corner of this sector.”
Oram was gratified to be able to interject. “View obviously is blocked from Earth. Dense nebulae, dust cloud, periodic flares screening out the infrared—maybe when the searcher for this sector made its pass, this world was at perihelion, on the opposite side of its star from Earth. Or the whole system could have been positioned exactly behind another intervening star or two. Not to mention the tricks that gravitational lensing can play with planetary scanners.” He tried for placating. “Don’t fault yourself, or the program, for the oversight.”
