TTUT1 Subroutine

  1. astro_module.f90
  2. astro_module
  3. TTUT1

public subroutine TTUT1(tt1, tt2, dt, ut11, ut12, j)

Time scale transformation: Terrestrial Time, TT, to Universal Time, UT1.

Status: canonical.

Notes

  1. TT1+TT2 is Julian Date, apportioned in any convenient way between the two arguments, for example where TT1 is the Julian Day Number and TT2 is the fraction of a day. The returned UT11,UT12 follow suit.

  2. The argument DT is classical Delta T.

Reference

  • Explanatory Supplement to the Astronomical Almanac, P. Kenneth Seidelmann (ed), University Science Books (1992)

History

  • IAU SOFA revision: 2019 June 20

Arguments

TypeIntentOptionalAttributesName
real(kind=wp), intent(in) :: tt1

TT as a 2-part Julian Date
real(kind=wp), intent(in) :: tt2

TT as a 2-part Julian Date
real(kind=wp), intent(in) :: dt

TT-UT1 in seconds
real(kind=wp), intent(out) :: ut11

UT1 as a 2-part Julian Date
real(kind=wp), intent(out) :: ut12

UT1 as a 2-part Julian Date
integer, intent(out) :: j

status: 0 = OK

Contents

Source Code

TTUT1

Source Code

    subroutine TTUT1 ( tt1, tt2, dt, ut11, ut12, j )

    implicit none

    real(wp),intent(in) :: tt1 !! TT as a 2-part Julian Date
    real(wp),intent(in) :: tt2 !! TT as a 2-part Julian Date
    real(wp),intent(in) :: dt !! TT-UT1 in seconds
    real(wp),intent(out) :: ut11 !! UT1 as a 2-part Julian Date
    real(wp),intent(out) :: ut12 !! UT1 as a 2-part Julian Date
    integer,intent(out) :: j !! status:  0 = OK

    real(wp) :: dtd

    !  Result, safeguarding precision.
    dtd = dt/d2s
    if ( abs(tt1)>abs(tt2) ) then
       ut11 = tt1
       ut12 = tt2 - dtd
    else
       ut11 = tt1 - dtd
       ut12 = tt2
    end if

    !  Status (always OK).
    j = 0

    end subroutine TTUT1