Long-term monitoring of delivered luminosity and calibration stability in ATLAS

Long-term monitoring of the delivered luminosity and of the calibration stability is an integral part of the ATLAS luminosity measurement at the LHC. Various methods are applied to monitor and correct the calibration of the main luminometer in ATLAS during the LHC Run-2: the LUCID-2 subdetector. Comparisons to independent luminosity-sensitive algorithms, such as track counting and the ATLAS calorimeters result in $0.7\%$-$1.3\%$ uncertainty in the ATLAS luminosity estimate from long-term effects. New procedures such as emittance scans and $Z$-boson counting allow for cross checks at the $2\%$-$5\%$ level.