The present note updates the information published in my recent monograph on The Galaxies of the Local Group .
Highlights include ( 1 ) the addition of the newly discovered Cetus dwarf spheroidal as a certain member of the Local Group , ( 2 ) an improved distance for SagDIG , which now places this object very close to the edge of the Local Group zero-velocity surface , ( 3 ) more information on the evolutionary histories of some individual Local Group members , and ( 4 ) improved distance determinations to , and luminosities for , a number of Local Group members .
These data increase the number of certain ( or probable ) Local Group members to 36 .
The spatial distribution of these galaxies supports Hubble ’ s claim that the Local Group “ is isolated in the general field. ” Presently available evidence suggests that star formation continued much longer in many dwarf spheroidals than it did in the main body of the Galactic halo .
It is suggested that “ young ” globular clusters , such as Ruprecht 106 , might have formed in now defunct dwarf spheroidals .
Assuming SagDIG , which is the most remote Local Group galaxy , to lie on , or just inside , the zero-velocity surface of the Local Group yields a dynamical age \gtrsim 17.9 \pm 2.7 Gyr .