Other forms: sightings
A sighting is an instance of discovering or observing something. You might use your telescope to watch the night sky for hours in the hope of a UFO sighting.
Your friend, an avid birdwatcher, gets excited at every woodpecker or heron sighting he makes, while you're more interested in sightings of used bookstores. A sighting of your favorite pop star — a quick glimpse as she ducks into a limousine — might be thrilling for you and your friend! Sighting, "an instance of catching sight," dates from the mid-19th century.