Questions for Mario Juric: do we have to keep sources associated with SSObjects together with regular sources associated with non-moving objects? It'd simplify database partitioning if we could segregate them into a separate SSSource table. If we can't, then:
when deciding on placement for sources associated with SSObjects, we should look at their ra/dec
add index on Source.ssObjectId, otherwise getting sources for a given object would require full Source table scan