The Gliese 783 system the Omec pass through in their search for the Votanis Collective fleet, does exist. It is a binary star system located in the Saggitarius constellation, roughly 20 light years away.
While at the Gliese 783 system in 1978, the Omec pick up on a music broadcast from Earth (20 light years away), a 1958 song called Rockin' Robin. As radio travels at the speed of light, a bubble of AM radio transmissions expands outward from our planet at the speed of one light year per year, something beautifully depicted by the opening sequence of Contact (1997).