There are 8 of them, and nobody knows for sure what they are. We'll all find out tomorrow. Hence my advice.
You can read about them here:
*Pilots’ Federation ALERT* It has been confirmed that the mysterious anomalies known as rogue signal sources are all converging on the core systems. P...
www.elitedangerous.com
As the rogue signal sources draw closer to human-occupied space, work is underway to initiate peaceful inter-species negotiations. Dr Elias Pope is a...
www.elitedangerous.com
*Pilots’ Federation ALERT* Contact has been lost with the Kingfisher megaship in the Hyades Sector YO-Q b5-1 system, just over a day since its arrival...
www.elitedangerous.com
Investigations in the Hyades Sector YO-Q b5-1 system have confirmed that Thargoid vessels attacked and destroyed the Kingfisher megaship. Vox Galactic...
www.elitedangerous.com
The Hyades Sector FB-N b7-6 system has been identified as the location where the rogue signal source named Taranis will finally arrive. Professor Ishm...
www.elitedangerous.com
(Sorry for all the walls of text, I still tried to keep it down to the bare minimum.)