astro::delta_t::algo4 Namespace Reference

Functions
constexpr auto	compute (const double year) -> double
	Compute ΔT for a decimal Gregorian year using algorithm 4.

Function Documentation

compute()

auto astro::delta_t::algo4::compute ( const double year ) ->double

nodiscardconstexpr

Compute ΔT for a decimal Gregorian year using algorithm 4.

Parameters

year	The year, of double type.

Returns

ΔT in seconds.

Exceptions

std::invalid_argument

if the year is >= 2035 or not finite.

Example

compute(2005.99999999....) returns ΔT for the last moment of year 2005.

Example

compute(1984.0) returns ΔT for the first moment of year 1984.

See also

IERS Bulletin A observations - https://www.iers.org/IERS/EN/Publications/Bulletins/bulletins.html

USNO ΔT predictions (deltat.preds) - https://maia.usno.navy.mil/ser7/deltat.preds

Generation record - https://github.com/0xf3cd/AstroTime-Analysis/blob/55115f4bf59cbdc47970b7f2d69a9715a467a3e9/DeltaT/algo4/record.json

Note

For year < 2005.0, algo2 is used instead.

For 2005.0 <= year < 2024.0, poly model trained on Bulletin A data is used.

For 2024.0 <= year < 2035.0, poly model trained on USNO ΔT predictions (deltat.preds) is used.

Frozen predecessor to algorithm 5, retained for historical comparison.