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 culled locating satellites may select those visible, or more preferably those locating satellites currently within a cone of space above the relevant base station are selected for communication by a mobile device within the service area of the base station. The inverted cone of space may be defined for each antenna structure for any given base station, and each has 360 degrees of coverage, or less than 360 degrees of coverage, with relevant locating satellites. Thus, cell sites may be specifically used as reference points for culling the ephemeris information used to expedite Assisted GPS location determinations.