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[logo] First Maps of the Soft X-ray Diffuse Background from the ROSAT XRT/PSPC All-Sky Survey

S.L. Snowden, M.J. Freyberg, P.P. Plucinsky, J.H.M.M. Schmitt, J. Trümper, W. Voges
(Max-Planck-Institut für extraterrestrische Physik, Garching)
R.J. Edgar, D. McCammon, W.T. Sanders
(University of Wisconsin - Madison)

Published in Astrophysical Journal Vol.454 (1995), pp.643-653

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Contents

  Introduction

  SXRB Maps

  Descriptions
     Data Format
     Processing

  Supplements
     SXRB exposure map
     Bright Source Catalog
     Astronomy Abstract Service



Introduction



  The paper (ApJ 454, 643) presents an initial version of the
  diffuse background results from the ROSAT soft X-ray all-sky survey.
  The maps cover approximately 98% of the sky in the 1/4 keV, 3/4 keV,
  and 1.5 keV bands, with about 2 degrees angular resolution and high
  sensitivity for low surface brightness extended features.
  The effects of non-X-ray contamination and X-rays of solar system
  origin have been eliminated to the greatest possible extent, but
  discrete X-ray sources have not been removed.
  The much improved angular resolution, statistical precision, and
  completeness of coverage of these maps reveals considerable structure
  over the entire $0.1-2.0$~keV energy range that was not observed
  previously. The data compare well with previous all-sky surveys in
  terms of absolute normalization and zero point.


  Here we present the data of Figs.5a,b,c and Fig.1 in electronic
  format (FITS).
  Maps were constructed using an equal-area (Aitoff-Hammer) projection.
  They contain 480 x 240 pixels with size 40' x 40'.
  Intensities are in units 10**(-6) counts/second/arcmin**2, exposure
  times in seconds. Galactic coordinates are used throughout, with
  longitude 0 centered and increasing to the left.


  You may use these maps for scientific purposes as long as reference
  is made to the relevant publication:


  S.L. Snowden, M.J. Freyberg, P.P. Plucinsky, J.H.M.M. Schmitt,
     J. Trümper, W. Voges, R.J. Edgar, D. McCammon, W.T. Sanders:
     Astrophysical Journal, Vol.454 (1995), pp.643-653
  

  Any comments, suggestions, problem reports etc. concerning the
  distribution of the electronic maps should be directed to:

  Michael Freyberg, MPE, Postfach 1603, D-85740 Garching, Germany

  email: mjf@mpe-garching.mpg.de
  Fax: +49-89-3299-3569



SXRB Maps


  Maps of the Soft X-ray Diffuse Background from the ROSAT XRT/PSPC
  All-Sky Survey are available in three energy bands, in FITS as well
  as in GIF format. Clicking on the small images will display full-size
  (842*595) versions (140 kB). If you want to directly download the
  files set your browser to "load to local disk..."

Image of C band
1/4 keV band (Fig.5c, comparable to Wisconsin C band)
count rates: FITS (480 kB) FITS gzip-ped (320 kB)
exposure: FITS (480 kB) FITS gzip-ped (320 kB)

Image of M band
3/4 keV band (Fig.5b, comparable to Wisconsin M band)
count rates: FITS (480 kB) FITS gzip-ped (320 kB)
exposure: FITS (480 kB) FITS gzip-ped (320 kB)

Image of IJ band
1.5 keV band (Fig.5a, comparable to Wisconsin IJ band)
count rates: FITS (480 kB) FITS gzip-ped (320 kB)
exposure: FITS (480 kB) FITS gzip-ped (320 kB)



Descriptions


  Data format:
    All maps are in zero-centered galactic coordinates with a Hammer-
    Aitoff equal-area projection. Longitude is increasing to the left.
    The maps are arrays of size 480*240 pixels (REAL*4) with pixel size
    40*40 arcmin**2. They contain a header (almost) compatible with the
    standard EXSAS header. However, some descriptor values are not yet
    fully implemented in the EXSAS package. An ASCII list of descriptors
    is also available. World coordinates are given in sky pixels (size
    0.5 arcsec).

    Units of the intensity maps (Figs.5a,b,c) for the three energy
    bands are 10**(-6) counts per second per arcmin**2.

    Units of the exposure maps (Fig.1 for IJ band) are seconds.
    Correction for deadtime has been applied but not for vignetting
    and shadowing of the field-of-view by the window support structure.
    C band and M band exposure maps are unpublished and appear here for
    the first time. They differ slightly from the IJ band exposure due
    to different screening.

  Processing:
    The user is asked to consult Sects.2.2 and 3 of ApJ 454, 643 for
    a full description of the processing and data reduction to avoid
    misleading scientific conclusions. Here only a summary is given:
    - SASS data used: BFLGZ.TEL
    - originally raw pulse heights, correction for PI channels applied
    - effective angular resolution is 115 arcmin
    - sources not excluded
    - particle background, scattered solar X-rays, long-term enhance-
      ments subtracted, excess contamination times excluded

Supplements

IJ band exposure map SXRB IJ band exposure map (Fig.1, GIF, 166 kB)
Maintained by mjf / 05-Jun-96