This catalog presents some of the results from 3 deep ROSAT High Resolution Imager (HRI) observations of the Orion Nebula star-forming region. The fields covered by the X-ray images contain over 1500 catalogued stars in a roughly 0.8 square degree region centered on the Trapezium. In all, 389 distinct X-ray sources were detected, at least two-thirds of which were associated with a single proper-motion cluster member. X-ray emission was detected from stars of all spectral types, from the massive O- and B-type components of the Trapezium to the coolest, low-mass pre-main-sequence (PMS) stars. In the research paper in which these data were presented (Gagne et al. 1995), the authors focussed primarily on X-ray emission from the late-type PMS stars. Of the ~100 late-type cluster members with measured spectral types, approximately three-fourths were detected; the authors derived X-ray luminosity upper limits for the remaining stars. They found that coronal X-ray emission appeared to turn on at around a spectral type of F6, with the upper envelope of activity increasing with decreasing effective temperature. The current database is a concatenation of Tables 2 and 3 from Gagne et al. (1995) which list the 389 distinct X-ray sources and their candidate optical counterparts. A detection criterion of 3 sigma was used, i.e., a sigal-to-noise ratio criterion of 3. 324 of the X-ray sources have a single candidate optical counterpart, 50 of the X-ray sources (listed in Table 3 of the original paper) have multiple candidates for the optical counterparts, and the remainder have no optical counterparts. Notice that Table 6 of Gagne et al. (1995) which presents a compilation of optical and X-ray data for a sub-group of the Orion stars for which data on the spectral types and the spectroscopic rotational velocities or the photometric rotational periods are available is not part of this database. This database was created at the HEASARC in December 1997 based on a computer-readable version of Tables 2 and 3 of Gagne et al. (1995) that was obtained from the CDS (their catalog J/ApJ/445/280). This is a service provided by NASA HEASARC .

This catalog presents some of the results from 3 deep ROSAT High Resolution Imager (HRI) observations of the Orion Nebula star-forming region. The fields covered by the X-ray images contain over 1500 catalogued stars in a roughly 0.8 square degree region centered on the Trapezium. In all, 389 distinct X-ray sources were detected, at least two-thirds of which were associated with a single proper-motion cluster member. X-ray emission was detected from stars of all spectral types, from the massive O- and B-type components of the Trapezium to the coolest, low-mass pre-main-sequence (PMS) stars. In the research paper in which these data were presented (Gagne et al. 1995), the authors focussed primarily on X-ray emission from the late-type PMS stars. Of the ~100 late-type cluster members with measured spectral types, approximately three-fourths were detected; the authors derived X-ray luminosity upper limits for the remaining stars. They found that coronal X-ray emission appeared to turn on at around a spectral type of F6, with the upper envelope of activity increasing with decreasing effective temperature. The current database is a representation of Table 6 from Gagne et al. (1995) (notice that the data given in Tables 2 and 3 of this reference is included in the HEASARC database ORIONXRAY, q.v.) which lists X-ray and other data for 175 Orion stars for which spectral types, spectroscopic rotational velocities, and/or spot-modulated photometric rotational periods are available. The X-ray data (either detections or upper limits) are given in the form of X-ray luminosities log Lx and X-ray to bolometric luminosity ratios (log Lx/Lbol). The conversion factor from HRI counts to log Lx was derived for each star based on (i) an assumed 1 keV Raymond and Smith thermal spectrum, (ii) a distance of 440 pc, and (iii) a column density of 2 x 10²¹ cm^-2 per magnitude of visual extinction A(V), where accurate A(V) values are used when available, or otherwise a moderate absorption of 0.25 magnitudes is assumed. Notice that, for stars not identified as candidate optical counterparts in Tables 2 and 3 of Gagne et al. (the HEASARC database ORIONXRAY), the derived upper limit to the X-ray luminosity usually corresponds to the 3 sigma upper limit to the observed count rate. For a handful of stars in the Trapezium region where a star was eliminated as a candidate optical counterpart, despite being within the source search circle, because a more likely counterpart had a smaller position offset, the upper limit corresponds to either half the observed X-ray source count rate or to 3 sigma, whichever is the highest. Such cases are indicated in this database by the presence of the string "NN" in the parameter 'Note'. This is a service provided by NASA HEASARC .

This is a catalog of galaxy clusters detected in a new ROSAT PSPC survey. The survey is optimized to sample, at high redshifts, the mass range corresponding to T > 5 keV clusters at z = 0. Technically, our survey is the extension of the 160 square degree survey (160d, the HEASARC Browse table called ROSGALCLUS). The authors use the same detection algorithm, thus preserving the high quality of the resulting sample; the main difference is a significant increase in sky coverage. The new survey covers 397 square degrees and is based on 1610 high Galactic latitude ROSAT PSPC pointings, virtually all of the pointed ROSAT data that were suitable for the detection of distant clusters. The search volume for X-ray luminous clusters within z < 1 exceeds that of the entire local universe (z < 0.1). The authors detected 287 extended X-ray sources with fluxes f_x > 1.4 x 10^-13 erg s^-1 cm^-2 in the 0.5 - 2 keV energy band, of which 266 (93%) are optically confirmed as galaxy clusters, groups or individual elliptical galaxies. The paper from which this table is extracted provides a description of the input data, the statistical calibration of the survey via Monte Carlo simulations, and the catalog of detected clusters. The authors also therein compare the basic results with those from previous, smaller area surveys and find good agreement for the logN - log S distribution and the local X-ray luminosity function. This sample clearly shows a decrease in the number density for the most luminous clusters at z > 0.3. The comparison of these ROSAT-derived fluxes with the accurate Chandra measurements for a subset of high-redshift clusters demonstrates the validity of the 400 square degree survey's statistical calibration. This Browse table contains the main cluster catalog (Table 4 of the reference paper) which comprises 242 serendipitously detected clusters of galaxies. It does not include 24 clusters within a redshift of 0.01 of the redshift of the target of the ROSAT observation (given in Table 5 of the reference paper), as these latter are not entirely serendipitous, 5 noncluster extended sources (given in Table 6 of the reference paper), nor 16 likely false X-ray detections (given in Table 7 of the reference paper). This table was created by the HEASARC in December 2007 based on the machine-readable version of Table 4 (the 'Cluster Catalog') obtained from the electronic ApJ website. This is a service provided by NASA HEASARC .

This table contains a catalog of 3405 X-ray sources from the ROSAT All Sky Survey (RASS) Bright Source Catalog which fall within the area covered by the 6dF Galaxy Survey (6dFGS). The catalog is count-rate limited at 0.05 ct s^-1 in the X-ray and covers the area of sky with Declination < 0 degrees and |b| > 10 degrees. The RASS-6dFGS sample was one of the additional target catalogs of the 6dFGS and as a result the authors obtained optical spectra for 2224 (65 per cent) RASS sources. Of these, 1715 (77%) have reliable redshifts with a median redshift of z = 0.16 (excluding the Galactic sources). For the optically bright sources (b_J <= 17.5) in the observed sample, over 90% have reliable redshifts. The catalog mainly comprises quasi-stellar objects (QSOs) and active galaxies but also includes 238 Galactic sources. Of the sources with reliable redshifts, the majority are type 1 active galactic nuclei (AGN, 69%), while 12% are type 2 AGN, 6% absorption-line galaxies and 13% are stars. The authors also identify a small number of optically faint, very low redshift, compact objects which fall outside the general trend in the b_J - z plane. The RASS-6dFGS catalog complements a number of Northern hemisphere samples, particularly the ROSAT Bright Source Catalogue-NRAO VLA Sky Survey (RBSC-NVSS) sample (Bauer et al. 2000, ApJS, 129, 547), and furthermore, in the same region of sky (-40 degrees < Declination < 0 degrees) reveals an additional 561 sources that were not identified as part of that sample. The authors detect 918 sources (27%) of the RASS-6dFGS sample in the radio using either the 1.4 GHz NVSS or the 843 MHz Sydney University Molonglo Sky Survey (SUMSS) catalogues and find that the detection rate changes with redshift. At redshifts larger than 1 virtually all of these sources have radio counterparts and with a median flux density of 1.15 Jy, they are much stronger than the median flux density of 28.6 mJy for the full sample. The authors attribute this to the fact that the X-ray flux of these objects is being boosted by a jet component, possibly Doppler boosted, that is only present in radio-loud AGN. The RASS-6dFGS sample provides a large set of homogeneous optical spectra ideal for future studies of X-ray emitting AGN. This table was created by the HEASARC in April 2010 based on an electronic version of Table 3 from the reference paper obtained from the MNRAS web site. This is a service provided by NASA HEASARC .

This table contains the galaxy cluster catalog from the second, larger phase of the Wide Angle ROSAT Pointed Survey (WARPS), an X-ray selected survey for high-redshift galaxy clusters. WARPS is among the largest deep X-ray cluster surveys and is being used to study the properties and evolution of galaxy clusters. The WARPS-II sample contains 125 clusters serendipitously detected in a survey of 301 ROSAT PSPC pointed observations and covers a sky area of 56.7 deg². Of these 125 clusters, 53 have not been previously reported in the literature. The authors have nearly complete spectroscopic follow-up of the clusters, which range in redshift from z = 0.029 to z = 0.92 with a median redshift of z = 0.29 and they find 59 clusters with z >= 0.3 (29 not previously reported in the literature) and 11 clusters with z >= 0.6 (6 not previously reported). They also define a statistically complete subsample of 102 clusters above a uniform flux limit of 6.5 x 10^-14 ergs/cm²/s (0.5 - 2.0 keV). In their paper, the authors also compare their redshifts, fluxes, and detection methods to other similar published cluster surveys and state that they find no serious issues with their measurements or completeness. The list of ROSAT pointings used in WARPS-II is given in Table 1 of the first reference paper. The WARPS-I cluster catalog (the second reference listed below) is also available in Browse as the WARPS table. This table was created by the HEASARC in September 2010 based on the combination of the electronic versions of Tables 2, 3, and 4 from the first reference paper which were obtained from the CDS (their catalog J/ApJS/176/374). This is a service provided by NASA HEASARC .

This table contains a source catalog based om XMM-Newton observations of the nearby galaxy M 33. In an XMM-Newton raster observation of this bright Local Group spiral galaxy, the authors studied the population of X-ray sources (X-ray binaries, supernova remnants) down to a 0.2-4.5 keV luminosity limit of 10³⁵ erg/s, more than a factor of 10 deeper than earlier ROSAT observations. European Photon Imaging Camera (EPIC) hardness ratios and optical and radio information are used to distinguish between different source classes. The survey detects 408 sources in an area of 0.80 square degree. The authors correlated these newly detected X-ray sources with earlier M 33 X-ray catalogs and information from optical, infra-red and radio wavelengths. As M 33 sources, theydetect 21 supernova remnants (SNR) and 23 SNR candidates, 5 super-soft sources and 2 X-ray binaries (XRBs). There are 267 sources classified as hard, which may either be XRBs or Crab-like SNRs in M 33 or background AGN. The 44 confirmed and candidate SNRs more than double the number of X-ray detected SNRs in M 33. 16 of these are proposed as SNR candidates from the X-ray data for the first time. On the other hand, there are several sources not connected to M 33: five foreground stars, 30 foreground star candidates, 12 active galactic nucleus candidates, one background galaxy and one background galaxy candidate. Extrapolating from deep field observations, 175 to 210 background sources are expected in this field. This indicates that about half of the sources which were detected are actually within M 33. This table was created by the HEASARC in October 2004 based on CDS table J/A+A/426/11/table3.dat This is a service provided by NASA HEASARC .