The aim of this project is to provide users with a set of small generic routines useful above all in astronomical and astrophysical context, written in Julia.
Included are also translations of some
IDL Astronomy User's Library
procedures, which are released under terms of
AstroLib.jl's functions are not drop-in replacement of those procedures, Julia
standard data types are often used (e.g.,
DateTime type instead of generic
string for dates) and the syntax may slightly differ. Refer to the
documentation of the functions for details.
Note: this project is a work-in-progress, only few procedures have been translated so far. In addition, function syntax may change from time to time. Check TODO.md out to see how you can help. Volunteers are welcome!
AstroLib.jl is available for Julia 1.0 and later versions, and can be
installed with Julia built-in package
manager. In a Julia session, after
entering the package manager mode with
], run the command
pkg> add AstroLib
Older versions of this package are also available for Julia 0.4-0.7.
Note that, in order to work, a few functions require external files, which are automatically downloaded when building the package. Should these files be missing for some reason, you will be able to load the package but some functions may not work properly. You can manually build the package with
After installing the package, you can start using it with
Many functions in
AstroLib.jl are compatible with
Measurements.jl package, which
allows you to define quantities with uncertainty and propagate the error when
performing calculations according to
propagation of uncertainty rules.
using AstroLib, Measurements
mag2flux(12.54 ± 0.03)
# => 3.499451670283562e-14 ± 9.669342299577655e-16
AstroLib.jl defines a new
Observatory type. This can be used to define a
new object holding information about an observing site. It is a
whose fields are
Stringtype): the name of the site
Float64type): North-ward latitude of the site in degrees
Float64type): East-ward longitude of the site in degrees
Float64type): altitude of the site in meters
Float64type): the number of hours of offset from UTC
The type constructor
Observatory can be used to create a new
object. Its syntax is
Observatory(name, lat, long, alt, tz)
name should be a string;
tz should be anything that can
be converted to a floating number with
alt should be a real
A predefined list of some observing sites is provided with
AstroLib.observatories constant. It is a dictionary whose keys are the
abbreviated names of the observatories. For example, you can access information
of the European Southern Observatory with
julia> obs = AstroLib.observatories["eso"]
Observatory: European Southern Observatory
altitude: 2347.0 m
time zone: UTC-4
You can list all keys of the dictionary with
Feel free to contribute new sites or adjust information of already present ones.
The package provides
Planet type to hold information about Solar System
planets. Its fields are
name: the name
radius: mean radius in meters
eqradius: equatorial radius in meters
polradius: polar radius in meters
mass: mass in kilogram
Orbital characteristics (epoch J2000):
ecc: eccentricity of the orbit
axis: semi-major axis of the orbit in meters
period: sidereal orbital period in seconds
The constructor has this syntax:
Planet(name, radius, eqradius, polradius, mass, ecc, axis, period)
The list of Solar System planets, from Mercury to Pluto, is available with
AstroLib.planets dictionary. The keys of this dictionary are the lowercase
names of the planets. For example:
mean radius: 2.4397e6 m
equatorial radius: 2.4397e6 m
polar radius: 2.4397e6 m
mass: 3.3011e23 kg
semi-major axis: 5.790905e10 m
period: 5.790905e10 s
Every function provided has detailed documentation that can be accessed at Julia REPL with
julia> @doc FunctionName
Full documentation of all functions can be accessed at http://juliaastro.github.io/AstroLib.jl/dev/. There you can find the complete list of all functions provided by this library.
How Can I Help?
You can contribute to the project in number of ways. You can translate more routines from IDL Astronomy User's Library or provide brand-new functions and improve existing ones. Also bug reports are encouraged.
This is not the only effort to bundle astronomical functions written in Julia language. Other packages useful for more specific purposes are available at https://juliaastro.github.io/.
The AstroLib.jl package is licensed under the MIT "Expat" License. The original author is Mosè Giordano.