Passive high-resolution series
A passive high-resolution series was a type of scan available to Starfleet engineers, used to scan interstellar artificial objects. 

In 2367, Commander La Forge and Lieutenant Barclay first attempted to scan the alien probe using a passive high-resolution series in the electromagnetic band from aboard the . The only radiation detected from the probe was visual, from 4500 and 7000 Ångstroms. ()
Scans