The Beta Antares Ship Yards were Federation shipyards located in the Antares sector.
The experimental USS Prometheus was launched from the Beta Antares Ship Yards on stardate 50749.5. (VOY: "Message in a Bottle" dedication plaque)
After the Attack on Mars in 2385, Admiral Jean-Luc Picard proposed to Starfleet that mothballed ships from Beta Antares and Eridani A be used to maintain the evacuation of Romulans from the Romulan supernova, albeit at a severely reduced level. The proposal was rejected. (PIC: "The End is the Beginning")