Precovery

In astronomy, precovery (short for "pre-discovery recovery") is the process of finding the image of an object in old archived images or photographic plates for the purpose of calculating a more accurate orbit. This happens most often with minor planets, but sometimes a comet, a dwarf planet, a natural satellite, or a star is found in old archived images; even exoplanet precovery observations have been obtained. While the term "precovery" refers to a pre-discovery image, "recovery" refers to imaging of a body which was lost to our view (as behind the Sun), but is now visible again (also see lost minor planets).

Calculating the orbit of an astronomical object involves measuring its position on multiple occasions. The more widely separated these are in time, the more accurately the orbit can be calculated. However, for a newly discovered object, only a few days' or weeks' worth of measured positions may be available, which is only sufficient for a preliminary (imprecise) orbit calculation.