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Foreground Data

Haslam 408 MHz All-Sky Map

Product Name
2014 Reprocessed Haslam 408 MHz
Coord. System
Galactic
Projection Type
HEALPix, ring

Description

Remazeilles et al. 2014 have re-evaluated and re-processed the rawest Haslam 408 MHz data, available from the Max Planck Institute for Radioastronomy Survey Sampler website, to produce an improved source-subtracted and destriped 408 MHz all-sky map. Large-scale striations associated with correlated low-frequency noise in the scan direction are reduced using a Fourier-based filtering technique. The most important improvement results from the removal of extra-galactic sources. An iterative combination of two techniques − two-dimensional Gaussian fitting and minimum curvature spline surface inpainting − are used to remove the brightest sources (with flux density larger than 2 Jy). Four products are made publicly available. They are described below. The sky maps are generated using the HEALPix sky pixelization scheme.

For a full discussion refer to Remazeilles et al. (2014).
Any questions may be sent to "mathieu.remazeilles@manchester.ac.uk"


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Detailed Product Descriptions


Product Name
Desourced destriped Haslam 408 MHz
Coord. System
Galactic
Projection Type
HEALPix, ring, Nside=512
Resolution
56 arcmin

Description

This is the main product. A re-processing of the data downloaded from the Max Planck Institute for Radioastronomy Survey Sampler website has been performed to improve both the removal of strong baseline striping and the removal of strong extra-galactic radio sources in the Haslam map. An iterative combination of two techniques − two-dimensional Gaussian fitting and minimum curvature spline surface inpainting − have been used for desourcing. In the 2014 Haslam map we get rid of the source residual artifacts that are still present in the LAMBDA post-processed 2003 version of the Haslam map. Note that the brightest Galactic sources have been retained in the map.

An image of this map is shown on LAMBDA Foreground Data Images Page.

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Product Name
Desourced destriped Haslam 408 MHz with small scales added
Coord. System
Galactic
Projection Type
HEALPix, ring, Nside=2048
Resolution
0 arcmin

Description

This is a high-resolution (Nside=2048, beam FWHM=0 arcmin) template of the desourced destriped 408 MHz all-sky map, in which small-scale fluctuations have been artificially added. This template is made available for the simulations of high resolution CMB and 21 cm intensity mapping experiments. Higher Nside maps with small-scales added are available on request from the authors.

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Product Name
Destriped Haslam 408 MHz
Coord. System
Galactic
Projection Type
HEALPix, ring, Nside=512
Resolution
56 arcmin

Description

A destriped-only version of the 408 MHz radio continuum all-sky map, with no desourcing, is also made available. Strong baseline striping has been reduced to 1 K but the extra-galactic sources have not been subtracted.

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Product Name
Bitmask Haslam 408 MHz
Coord. System
Galactic
Projection Type
HEALPix, ring, Nside=512
Resolution
56 arcmin

Description

This is the bitmask of the extra-galactic sources that have been subtracted. Each bit indicates the processing technique applied to the source (bit 0: Gaussian fitting, bit 1: Inpainting).


More details can be found in

"An improved source-subtracted and destriped 408 MHz all-sky map", Remazeilles, M., Dickinson, C., Banday, A. J., Bigot-Sazy, M.-A., Ghosh, T., 2014, arXiv:1411.3268

Jodrell Bank Centre for Astrophysics website:

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Previous Haslam 408 MHz Data Products

Product Name
Haslam 408 MHz
Coord. System
Galactic
Projection Type
HEALPix, nested, res 9 (Nside=512)
Resolution
~1°

Description

The 408 MHz radio continuum all-sky map of Haslam et al. (see references below) combines data from four different surveys. The map is dominated by synchrotron emission.

Two versions of the map are supplied:

  • The destriped/desourced (dsds) version was constructed from survey data obtained from the archives of the NCSA ADIL in galactic coordinates. The data were then transformed to a celestial coordinate grid and subsequently processed further in both the Fourier and spatial domains to mitigate baseline striping and strong point sources. These data were then interpolated onto a HEALPix projection.
  • A second version was constructed from data downloaded from the Max Planck Institute for Radioastronomy Survey Sampler website. This version, labeled 'nofilt' on the data download page, was not processed to remove baseline striping or strong point sources.

More details can be found in:

"A 408 MHz All_Sky Continuum Survey. II. The Atlas of Contour Maps",
Haslam, et al., 1982

"A 408 MHz All_Sky Continuum Survey. I. Observations at southern declinations and for the North Polar region",
Haslam, et al., 1981

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Goddard Space Flight Center, National Aeronautics and Space Administration
HEASARC Director: Dr. Alan P. Smale
LAMBDA Director: Dr. Eric R. Switzer
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Web Curator: Mr. Michael R. Greason