Dust Maps

Usage

julia> dustmap = SFD98Map();

julia> dustmap(0, 2)
0.020303287464050277

julia> l = range(-π, π, length=5)
-3.141592653589793:1.5707963267948966:3.141592653589793

julia> b = range(-π/2, π/2, length=5)
-1.5707963267948966:0.7853981633974483:1.5707963267948966

julia> [dustmap(l[i], b[j]) for i in 1:length(l), j in 1:length(b)]
5×5 Array{Float64,2}:
 0.0159853  0.105782    1.40486  0.0158918  0.0119615
 0.0159853  0.0268289   3.47788  0.0654852  0.0119615
 0.0159853  0.0343457  99.6976   0.103875   0.0119615
 0.0159853  0.0432165   2.60569  0.0178195  0.0119615
 0.0159853  0.105782    1.40486  0.0158918  0.0119615

Advanced Usage

Our dust maps also have native support for Unitful.jl and Measurements.jl.

julia> using Measurements, Unitful

julia> l = 45u"°"; b=0u"°";

julia> dustmap = SFD98Map();

julia> dustmap(l, b)
6.4290331211742355 mag

julia> l = l ± 0.1u"°"; b = b ± 0.3u"°";

julia> dustmap(l, b)
6.4 ± 5.7 mag

API/Reference

Schlegel, Finkbeiner and Davis (1998)

DustExtinction.SFD98Map — Type

SFD98Map([mapdir])

Schlegel, Finkbeiner and Davis (1998) dust map.

The first time this is constructed, the data files required will be downloaded and stored in a directory following the semantics of DataDeps.jl. To avoid being asked to download the files, set the environment variable DATADEPS_ALWAYS_ACCEPT to true. You can also provide the directory of the two requisite files manually instead of relying on DataDeps.jl. Internally, this type keeps the FITS files defining the map open, speeding up repeated queries for E(B-V) values.

References

Schlegel, Finkbeiner and Davis (1998)

source

(dustmap::SFD98Map)(l::Real, b::Real)
(dustmap::SFD98Map)(l::Quantity, b::Quantity)

Get E(B-V) value from a SFD98Map instance at galactic coordinates (l, b), given in radians. Uses bilinear interpolation between pixel values. If l and b are Unitful.Quantity they will be converted to radians and the output will be given as UnitfulAstro.mag.

Example

julia> using DustExtinction

julia> m = SFD98Map();

julia> m(1, 2)
0.013439524544325624

julia> l = 0:0.5:2; b = 0:0.5:2;

julia> m.(l, b)
5-element Array{Float64,1}:
 99.69757461547852    
  0.10180447359074371 
  0.019595484241066132
  0.010238757633890877
  0.01862100327420125

source