Locating satellites (e.g., GPS) are culled into a preferred group having a longest dwell time based on a time passing through an ellipsoid arc path through a cone of space, and communicated to mobile devices within a particular region (e.g., serviced by a particular base station). The locating satellites may be culled into a prioritized list. Each satellite is assigned an order of precedence based on a remaining dwell time within a primary inverted cone. Thus, a number ‘N’ of satellite's ephemeris data may be used, along with a preferred ‘order of precedence’ for secondary satellites to be used as backups as necessary.