The Ram Tah Mission
The Ram Tah mission is available when you dock at Felice Dock in the Meene system, and involves you scanning ancient obelisks at various different Guardian sights for a nice hefty 101m Cr payout.
Down to Earth Astronomy also has an excellent YouTube guide on the missions:
Guardian Modules and Weapon Blueprints
Guide from Reddit:
Down to Earth Astronomy YouTube guide:
Guardian SLF Blueprints