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ROSAT Guest Observer Facility

[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