Ground-based measurements began in 1956, at Halley Bay. A few years later these were supplemented by measurements at the South Pole and elsewhere on the continent.  Satellite measurements began in the early 70's, but the first really comprehensive satellite data came in 1978, with the TOMS (total ozone mapping spectrometer) and SBUV (solar backscatter UV) instruments on Nimbus-7.  The Nimbus-7 TOMS,  which finally broke down on 7 May 1993, is the source for most of  the pretty pictures that one sees in review articles as well as the popular press. (See http://jwocky.gsfc.nasa.gov/). Today  there are several satellites monitoring ozone and other atmospheric gases; instruments on NASA's UARS (Upper Atmosphere Research Satellite) simultaneously measure ozone, chlorine monoxide (ClO), and  stratospheric pressure and temperature.