JHKL light curves from 1972–2013 (open squares: Mk II, filled triangles: SIRIUS). The errors at JHK are less than ± 0.03 mag, while those at L are about ± 0.05 mag. Dotted lines show linear regression trends based on the pre-1998 data. Vertical dotted lines indicate periastron passages (the corresponding phases are indicated). In J, H, and to a lesser degree in K and L, η Car did not follow the long-term linear brightening trends after the 1998 periastron passage.