Satellite Catalog Number

Common card · No. 411901

The Satellite Catalog Number (SATCAT), also known as NORAD Catalog Number, NORAD ID, USSPACECOM object number, SSN number, SCC number, and SSC number, is a sequential five-digit number assigned by the United States Space Command (USSPACECOM), and previously the North American Aerospace Defense Command (NORAD). Numbers are assigned in the order discovery to all artificial objects tracked in earth's orbit, in contrast to the other primary method of identifying on-orbit satellites, the international designator which assigns numbers based purely off of launch dates. For example, catalog number 1 is the Sputnik 1 launch vehicle, and the Sputnik 1 satellite assigned catalog number 2. The SATCAT number is the primary identifier of the specific object described in a two-line element set.

Read on Wikipedia