README.md

Orbits.jl

Flexible and fast astronomical orbits (originally a submodule of Transits.jl).

The goals of this package are, in this order:

• have a simple interface with high composability
• be flexible with respect to numeric types and application
• be fully compatible with ChainRules.jl automatic differentiation (AD) system to leverage the derived analytical gradients
• provide a codebase that is well-organized, instructive, and easy to extend
• maintain high performance: at least as fast as similar tools

Installation

To install use Pkg. From the REPL, press ] to enter Pkg-mode

pkg> add Orbits

If you want to use the most up-to-date version of the code, check it out from main

pkg> add Orbits#main

Usage

using Orbits
using Plots
using Unitful, UnitfulAstro
using UnitfulRecipes

# orbital params for SAO 136799
distance = inv(6.92e-3)u"pc"

orbit = KeplerianOrbit(;
    period = 40.57u"yr",
    ecc = 0.42,
    Omega = 318.6u"°",
    tp = 1972.12u"yr",
    incl = 54.7u"°",
    a = 0.154u"arcsecond" * distance |> u"AU",
    omega = 72.6u"°",
)

# get position at specific time
t = 2022.134u"yr"
pos = relative_position(orbit, t)
ra_off, dec_off = @. pos[1:2] / distance |> u"arcsecond"

2-element Vector{Quantity{Float64, NoDims, Unitful.FreeUnits{(″,), NoDims, nothing}}}:
  0.14482641030730156 ″
 -0.07816487001285195 ″

---

# plot using Unitful recipes
plot(orbit; distance, lab="", leg=:topleft)
scatter!([0u"arcsecond" ra_off], [0u"arcsecond" dec_off],
          c=[:black 1], m=[:+ :o], lab=["SAO 136799A" "B ($t)"])

---

pa = round(Orbits.position_angle(orbit, t), sigdigits=5)
sep = round(u"AU", Orbits.separation(orbit, t), sigdigits=5)
pa, sep

(118.36, 23.782 AU)

Contributing and Support

If you would like to contribute, feel free to open a pull request. If you want to discuss something before contributing, head over to discussions and join or open a new topic.