Active Cavity Radiometer Irradiance Monitor (ACRIM) III monitors the total variability of solar irradiance with active cavity radiometer solar monitoring sensors. ACRIM III was successfully launched on board the ACRIMSAT spacecraft on December 20, 1999. ACRIM III data are reprocessed every 90 days to utilize instrument recalibration.

"The Active Cavity Radiometer Irradiance Monitor 3 (ACRIM 3) instrument was turned off in November 2013. ACRIMSAT stopped communicating in December 2013. A reprocessed data set spanning April 5 2000 to March 5 2013 was uploaded in May 2013. Data from March 6 to September 17 2013 is being uploaded at present. Data taken during September 18 - November 2013 is being evaluated and will be included in the final version of ACRIM 3 data to be delivered by August 2015."