The first satellite series dedicated to meteorological observations. TIROS-1, launched in April 1960, carried a vidicon television camera to provide visible images of the earth. TIROS-8, launched in December 1963, introduced APT, while TIROS-9, launched in January 1965 in a sun-synchronous orbit, produced the first global composite imagery. The first ten satellites in the TIROS series, launched from 1960 to 1965, were experimental systems. From 1966 to 1969 TIROS satellites were used for the first series of operational polar-orbiting satellites, the TIROS Operational System. These satellites were named ESSA-1 through ESSA-9. A second series of operational satellites, the Improved TIROS Operational System, was launched between 1970 and 1976 and includes the ITOS-1 satellite, as well as NOAA-1 through 5. The current polar-orbiting series began with TIROS-N, launched on 13 October 1978, and continuing with NOAA-6, -7, and -12. NOAA-8 through -11 and NOAA-14 were modified versions of TIROS- N, designated Advanced TIROS-N satellites. Like GOES, the polar-orbiting satellites are typically given a letter designation as they are built and then renamed with a number after they are successfully launched. Thus NOAA-J became NOAA-14 after launch. TIROS-N is an exception to this rule.