We searched the Sloan Digital Sky Survey for outer halo globular clusters ( GCs ) around M31 .
Our search of non-stellar objects , within the limits of 0.3 \leq ( g - i ) _ { 0 } \leq 1.5 and 14.0 \leq r _ { 0 } \leq 19.0 concentrated in some remote areas of the extended halo , to a maximum projected distance of 240 kpc , for a total of approximately 200 \textrm { deg } ^ { 2 } .
Another \sim 50 \textrm { deg } ^ { 2 } , \sim 5 - 75 kpc from M31 , were surveyed as test areas .
In these areas , we identified 39 GCs and 2 GC candidates 84 \% of the previously known GCs ( 93 % of the “ classical GCs ” and 40 % of the “ halo extended clusters ” , on the cluster classification scheme of Huxor et al . ) .
For the entire survey , we visually inspected 78,516 objects for morphological evidence of cluster status , and we identified 18 new clusters , and 75 candidate clusters .
The new clusters include 15 classical globulars and three clusters of lower density .
Six of the clusters reside in the remote areas of the outer halo , beyond projected distances of 100 kpc .
Previously , only MGC1 was found beyond this limit at 117 kpc .
The farthest cluster discovered in this survey lies at a projected radius of 158 kpc from M31 , assuming that the M31 distance is 780 kpc .