HEALPix, nested, res 10 (Nside=1024) and res 9 (Nside=512)
Original Data Source
D. Finkbeiner (see 2003 reference below) has assembled a full sky Halpha map using data from several surveys: the Wisconsin H-Alpha Mapper (WHAM), the Virginia Tech Spectral-Line Survey (VTSS), and the Southern H-Alpha Sky Survey Atlas (SHASSA). The composite map can be used to provide limits on free-free foreground emission.
The H-alpha data products provided here are direct copies of the version 1.1 products distributed on D. Finkbeiner's website (see below). The data are available in three projections: HEALPix Nside=1024, HEALPix Nside=512, and Cartesian 8640 x 4320 projection (2.5 arcmin pixels). For each pixelization, three files are available: the H-alpha map itself, a 'mask' map indicating how each pixel in the composite map was processed, and an estimated error map. Note that the data are undersampled at the HEALPix Nside=512 pixelization (pixel size 6.9 arcmin). HEALPix Nside=256 products are available from Finkbeiner's website.
More details can be found in:
25 Jan 2003:
27 Jul 2003: