Interp10A returns ΔT at a date, accurate from years 1620 to 2010.

Poly1800to1899 returns a polynomial approximation of ΔT valid for years 1800 to 1899.

Poly1800to1997 returns a polynomial approximation of ΔT valid for years 1800 to 1997.

Poly1900to1997 returns a polynomial approximation of ΔT valid for years 1900 to 1997.

Poly948to1600 returns a polynomial approximation of ΔT valid for calendar years 948 to 1600.

PolyAfter2000 returns a polynomial approximation of ΔT valid for calendar years after 2000.

PolyBefore948 returns a polynomial approximation of ΔT valid for calendar years before 948.