a) Eight SDSS observations of asteroid (5129) Groom plotted in the scheme proposed. The error bars represent the errors transformed to PC space. The spectra of the observations are plotted together in the lower corner of the graph. The specific SDSS observation IDs are s14307, s0e2e7, sca267, sc8e1d, scf0dc, scdde4, scc719, and scbc65. b) Three asteroids with multiple observations presenting spectral variability. The SDSSMOC observation IDs for each asteroid: (2252) CERGA (blue): s3bafc, s3f6f3, s3eea4, s41189, s424bf, sbbb68, sf0125, sef985, sef5d2; (3631) Sigyn (purple): s16290, s16001, sf0e38, s042fc, s132c2; and (55926) 1998 FE60 (black): s17150, s18825, s17c18, s3924d, s2cd9b.