BRANDUARDIRAYMONT, G; MASON, KO; WARWICK, RS; CARRERA, EJ; GRAFFAGNINO, VG; MITTAZ, JPD; ... ROWANROBINSON, M; + view all BRANDUARDIRAYMONT, G; MASON, KO; WARWICK, RS; CARRERA, EJ; GRAFFAGNINO, VG; MITTAZ, JPD; PUCHNAREWICZ, EM; SMITH, PJ; BARBER, CR; POUNDS, KA; STEWART, GC; MCHARDY, IM; JONES, LR; MERRIFIELD, MR; FABIAN, AC; MCMAHON, RG; WARD, MJ; GEORGE, IM; JONES, MH; LAWRENCE, A; ROWANROBINSON, M; - view fewer (1994) THE UK DEEP AND MEDIUM SURVEYS WITH ROSAT - LOG-N-LOG-S RELATION. MON NOT R ASTRON SOC , 270 (4) 947 - 957.
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We have carried out a soft X-ray survey of the sky using the ROSAT Position Sensitive Proportional Counter (PSPC) in a region of very low Galactic column density (N-H = 6-9 x 10(19) cm(-2)). The data consist of a deep > 70 ks pointing (the Deep Survey) and six pointings at lower sensitivity (13-20 ks; the Medium Survey). We detect a total of 141 sources over the 0.9 deg(2) of sky area used. The faintest source detected has a flux of 3.2 x 10(-15) erg cm(-2) s(-1) (0.5-2.0 keV). We present the source number-nux distribution, and we compare it with the distributions constructed from other ROSAT observations and from surveys carried out with X-ray instruments operating at higher energies. We estimate the contribution of the resolved sources to the soft X-ray background by direct comparison of their integrated spectrum with that of the diffuse background: 44 per cent of the extragalactic X-ray background between 0.5 and 2.0 keV is resolved directly into discrete sources whose average spectrum is steeper than that of the background. Integration of our number-flux relation to infinite flux produces a background resolved fraction of 44 +/- (56)(5) per cent (0.5-2.0 keV). Limits on the slope of the log N-log S curve at very faint fluxes are set by the measured value of the X-ray background.
|Title:||THE UK DEEP AND MEDIUM SURVEYS WITH ROSAT - LOG-N-LOG-S RELATION|
|Keywords:||GALAXIES, ACTIVE, DIFFUSE RADIATION, X-RAYS, GENERAL, MEDIUM-SENSITIVITY SURVEY, X-RAY SURVEY, LUMINOSITY FUNCTION, ORIGIN, EMISSION, DENSITY, COUNTS|
|UCL classification:||UCL > School of BEAMS > Faculty of Maths and Physical Sciences > Space and Climate Physics|
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