An HI-based Map of Interstellar Reddening

Motivated by the recent work of Liszt (2014), Brandon Hensley and I took a closer look at the ratio of interstellar reddening and HI column density, E(B-V)/NHI. We generated a new E(B-V) map based on the new HI data from HI4PI that addresses many of the systematics in widely used reddening maps based on dust emission, e.g. Schlegel, Finkbeiner, and Davis (1998). Our map covers 40% of the sky centered around the Galactic poles and has an angular resolution of 16.1′.

The content is located as follows:

  • The paper has been submitted to ApJ and is already available on arxiv.
  • The new reddening map in the HEALPix format can be found on NASA LAMBDA. We also publish the underlying HI column density map for absolute velocities lower than 90 km/s.
  • The data has also been published on the Harvard dataverse (doi:10.7910/DVN/AFJNWJ)
  • A short notebook with examples on how to use the map is available on github . This includes:
    • Conversions from E(B-V) to extinction in a larger number of bandpasses, according to Schlafly & Finkbeiner (2011).
    • A function to extract the E(B-V) value for a particular line of sight.

The HI4PI Survey

The HI4PI Survey, published in A&A, is a new full-sky survey of atomic neutral hydrogen (HI), merging the data from the GASS and EBHIS surveys. The HI column density map as well as the full spectroscopic data set can be accessed on CDS in various formats and projections.


The Effelsberg-Bonn HI Survey

The Effelsberg-Bonn HI Survey EBHIS is a new full-sky survey of the northern hemisphere in HI, conducted with the Effelsberg 100-m telescope. The full spectroscopic data set is publicly available through CDS.

WHAMS H-Alpha data

Check out this post.