Iers Conventions Jl

IERSConventions.jl

IERS Conventions for Earth orientation computations. Repo: JuliaSpaceMissionDesign/IERSConventions.jl

Available Models

Frame Rotations

# GCRF -> other frames (pass IERS model as first arg)
D = iers_rot3_gcrf_to_itrf(iers2010b, tt_s)     # DCM
D = iers_rot3_gcrf_to_mod(iers2010b, tt_s)
D = iers_rot3_gcrf_to_tod(iers2010b, tt_s)
D = iers_rot3_gcrf_to_pef(iers2010b, tt_s)
D = iers_rot3_gcrf_to_cirf(iers2010b, tt_s)
D = iers_rot3_gcrf_to_tirf(iers2010b, tt_s)
D = iers_rot3_gcrf_to_gtod(iers2010b, tt_s)

# Higher-order derivatives
D, dD       = iers_rot6_gcrf_to_itrf(iers2010b, tt_s)
D, dD, ddD  = iers_rot9_gcrf_to_itrf(iers2010b, tt_s)

# Inverse rotations
D = iers_rot3_itrf_to_cirf(iers2010b, tt_s)
D = iers_rot3_itrf_to_mod(iers2010b, tt_s)

EOP Data Access

eop_xp(model, tt_c)       # Polar motion x [rad]
eop_yp(model, tt_c)       # Polar motion y [rad]
eop_lod(model, tt_c)      # Length of day [s]
eop_δX(model, tt_c)       # CIP correction X [rad]
eop_δY(model, tt_c)       # CIP correction Y [rad]

Internal Functions

iers_obliquity(model, tt_c)     # Mean obliquity
iers_gmst(model, tt_s)          # Greenwich Mean Sidereal Time
iers_gast(model, tt_s)          # Greenwich Apparent Sidereal Time
iers_earth_rot_rate(model, tt_c) # Earth rotation rate

Key Conventions

• Time: TT seconds since J2000 (internally converted to centuries where needed)
• rot3/6/9/12 naming: rotation + Nth-order derivative
• Returns DCM from ReferenceFrameRotations.jl
• Registers UT1 timescale with Tempo.jl on package init
• EOP data interpolated via Akima splines from JSMDUtils