Abstract: Onboard geolocation of target pixels in images captured by a spacecraft is disclosed. By performing the geolocation onboard the spacecraft considerable time is saved. The geolocation may be based on timestamped ephemeris data and timestamped attitude data of the spacecraft. In one aspect, initial geolocation data is refined based on a digital construct. In one aspect, the accuracy of the ephemeris data and/or the attitude data are improved based on refinements made to the initial geolocation data. For example, corrections may be made to attitude and/or orbit filter parameters based on the refinements made to the initial geolocation data. In one aspect, the accuracy of the attitude data and/or the ephemeris data may be improved by the use of state information. The state information may be determined at a ground computing station based on information not available to the spacecraft such as Ground Control Points and/or Star Control Points.