Galactic extinction maps created by An, Beers, Chiti (2024, ApJS in press):
https://arxiv.org/abs/2404.14626
Example scripts in both IDL and Python are provided below to obtain the mean E(B-V) for a specified sightline and distance.
There are two alternative extinction maps provided. The first ("extinction_map") is derived using a fixed value for the total-to-selective extinction ratio, R(V), set at the standard value (=3.1). The second map ("extinction_map2") is based on a scenario where R(V) varies during the parameter search. Refer to Sections 4 and 6 in ABC for detailed descriptions of each case.
In order to run these scripts, you may need to install the HEALPix subroutines from the following webpages:
IDL: see https://healpix.sourceforge.io/doc/html/install.htm
Python: see https://healpy.readthedocs.io/en/latest/install.html
- Example script in IDL
(1) Compute the E(B-V) for the Pleiades located at Galactic coordinates of (l, b) = (120, 10) degrees and a distance of 135.8 pc, utilizing the default extinction map with a total-to-selective extinction ratio of R(V)=3.1:
IDL> get_extinction, 166.4628, -23.6146, 135.8
E(B-V) = 0.029 +/- 0.009
Note that useful E(B-V) are found within 97 - 2483 pc.
(2) Repeat the computation outlined above, this time utilizing an alternative extinction map that incorporates a variation in R(V):
IDL> get_extinction, 166.4628, -23.6146, 135.8, /get_rv
E(B-V) = 0.031 +/- 0.008
R(V) = 3.866
Note that useful E(B-V) are found within 97 - 2403 pc.
- Example script in Python
(1) Compute the E(B-V) for the Pleiades located at Galactic coordinates of (l, b) = (120, 10) degrees and a distance of 135.8 pc, utilizing the default extinction map with a total-to-selective extinction ratio of R(V)=3.1:
>>> from get_extinction import get_extinction
>>> get_extinction(glon=166.4628, glat=-23.6146, dpc=135.8)
E(B-V) = 0.029 +/- 0.009
Note that useful E(B-V) is found within 97 - 2483 pc.
(2) Repeat the computation outlined above, this time utilizing an alternative extinction map that incorporates a variation in R(V):
>>> from get_extinction import get_extinction
>>> get_extinction(glon=166.4628, glat=-23.6146, dpc=135.8, get_rv=True)
E(B-V) = 0.031 +/- 0.008
R(V) = 3.866
Note that useful E(B-V) is found within 97 - 2403 pc.