This page includes data files for all-sky maps of Galactic interstellar extinction that have been calculated using 2MASS survey and the NICER and NICEST methods. The details of the calculations are given in a paper M. Juvela, J. Montillaud (2016a, A&A 585, 38) . Maps give the J band extinction in magnitudes and the files are in Healpix format with a resolution parameter NSIDE=2048 and NESTED pixelisation scheme. The resolution (FWHM of Gaussian beam) is 3.0, 4.5, or 12 arcmin, as indicated by the file names. M1, M2a, and M2b refer to different assumptions of stellar intrinsic colours.
The files are suitable for a quick look at relative extinction values in small sky regions. The absolute level of the maps and the relative extinction values at scales of several degrees are not well determined because of the unknown relative 3D distribution of stars and dust clouds. For individual clouds, more detailed analysis of near-infrared extinctionand possibly higher resolution maps can be found in the literature. Some references are included in Juvela & Montillaud (2016a).
For alternative near-infrared extinction estimates and extinction at optical wavelengths, see for example http://darkclouds.u-gakugei.ac.jp/ .
The following maps have been calculated for NSIDE=2048 pixels. The pixel size 1.72 arcmin and the file size 193MB each.
The following extinction map has been calculated at a resolution of 3.0 arcmin, using Healpix pixelization with NSIDE=4096. The pixel size is thus about 0.86 arcmin and the file size 769MB. The calculations is done twice, the second round using the initial NICER map as a template of the spatial extinction variations within each beam. This is expected to result in smaller noise in the final map (for details, see Juvela & Montillaud 2016b, A&A 585, 78 ).
The following NICEST maps have been calculated onto NSIDE=2048 pixels. The pixel size is thus about 1.72 arcmin and each file is 193MB in size.