add EclipticCoords

JuliaAstro · Jan 13, 2023 · e1af8a5 · e1af8a5
1 parent 6c8849b
commit e1af8a5
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diff --git a/src/SkyCoords.jl b/src/SkyCoords.jl
@@ -101,11 +101,15 @@ function precess_from_j2000(equinox)
     zrotmat(-z) * yrotmat(theta) * zrotmat(-zeta)
 end
 
+ecliptic_obliquity(y) = deg2rad(23.439291 - 0.0130042 * (y - 2000.0))
+
 # -----------------------------------------------------------------------------
 # Type-dependent methods
 
 lon(c::GalCoords) = c.l
 lat(c::GalCoords) = c.b
+lat(c::EclipticCoords) = c.lat
+lon(c::EclipticCoords) = c.lon
 lon(c::AbstractSkyCoords) = c.ra
 lat(c::AbstractSkyCoords) = c.dec
 
@@ -121,6 +125,9 @@ rotmat(::Type{<:ICRSCoords}, ::Type{<:ICRSCoords}) = I
 rotmat(::Type{<:GalCoords}, ::Type{<:GalCoords}) = I
 rotmat(::Type{<:FK5Coords{e}}, ::Type{<:FK5Coords{e}}) where {e} = I
 
+@generated rotmat(::Type{<:EclipticCoords{e}}, ::Type{<:ICRSCoords}) where {e} = xrotmat(ecliptic_obliquity(e))
+@generated rotmat(::Type{<:ICRSCoords}, ::Type{<:EclipticCoords{e}}) where {e} = xrotmat(-ecliptic_obliquity(e))
+
 @generated rotmat(::Type{<:FK5Coords{e1}}, ::Type{<:ICRSCoords}) where {e1} =
     precess_from_j2000(e1) * ICRS_TO_FK5J2000
 @generated rotmat(::Type{<:FK5Coords{e1}}, ::Type{<:GalCoords}) where {e1} =

diff --git a/src/types.jl b/src/types.jl
@@ -72,6 +72,18 @@ FK5Coords{e,F}(c::T) where {e,F,T<:AbstractSkyCoords} = convert(FK5Coords{e,F},
 constructorof(::Type{<:FK5Coords{e}}) where {e} = FK5Coords{e}
 
 
+struct EclipticCoords{e,T<:AbstractFloat} <: AbstractSkyCoords
+    lon::T
+    lat::T
+    EclipticCoords{e,T}(lon, lat) where {e,T<:AbstractFloat} = new(mod2pi(lon), lat)
+end
+EclipticCoords{e}(lon::T, lat::T) where {e,T<:AbstractFloat} = EclipticCoords{e,T}(lon, lat)
+EclipticCoords{e}(lon::Real, lat::Real) where {e} = EclipticCoords(promote(float(lon), float(lat))...)
+EclipticCoords{e}(c::AbstractSkyCoords) where {e} = convert(EclipticCoords{e}, c)
+EclipticCoords{e,F}(c::AbstractSkyCoords) where {e,F} = convert(EclipticCoords{e,F}, c)
+constructorof(::Type{<:EclipticCoords{e}}) where {e} = EclipticCoords{e}
+
+
 # Scalar coordinate conversions
 Base.convert(::Type{T}, c::T) where {T<:AbstractSkyCoords} = c
 
@@ -85,3 +97,4 @@ Base.:(==)(a::T, b::T) where {T<:AbstractSkyCoords} = lon(a) == lon(b) && lat(a)
 Base.isapprox(a::ICRSCoords, b::ICRSCoords; kwargs...) = isapprox(SVector(lon(a), lat(a)), SVector(lon(b), lat(b)); kwargs...)
 Base.isapprox(a::GalCoords, b::GalCoords; kwargs...) = isapprox(SVector(lon(a), lat(a)), SVector(lon(b), lat(b)); kwargs...)
 Base.isapprox(a::FK5Coords{e}, b::FK5Coords{e}; kwargs...) where {e} = isapprox(SVector(lon(a), lat(a)), SVector(lon(b), lat(b)); kwargs...)
+Base.isapprox(a::EclipticCoords{e}, b::EclipticCoords{e}; kwargs...) where {e} = isapprox(SVector(lon(a), lat(a)), SVector(lon(b), lat(b)); kwargs...)