This table contains the results from a spectroscopic study of 1080 nearby active M dwarfs, selected by correlating the Two Micron All Sky Survey (2MASS) and ROSAT catalogs at galactic latitudes greater than 15 degrees above or below the Galactic Plane and using a matching radius of 20 arcseconds, as well as color cuts (J-H < 0.75, H-K > 0.15 and 0.8 < J-K < 1.1) designed to select M dwarfs. The authors have derived the spectral types and estimated distances for all of their stars. The spectral types range between K5 and M6. Nearly half of the stars lie within 50 pc. The authors have measured the equivalent width of the H-alpha emission line. Their targets show an increase in chromospheric activity from early to mid-spectral types, with a peak in activity around M5. Using the count rate and hardness ratios obtained from the ROSAT catalog,the authors have derived the stellar X-ray luminosities. Their stars display a "saturation-type" relation between the chromospheric and coronal activity. The relation is such that log L_X/L_bol remains "saturated" at a value of approximately -3 for varying H-alpha equivalent width. The authors have found 568 matches in the USNO-B catalog and have derived the tangential velocities v_tan for these stars. There is a slight trend of decreasing chromospheric activity with age, such that the stars with higher v_tan values have lower H-alpha equivalent widths. The coronal emission, however, remains saturated at a value of log L_X/L_bol ~ -3 for varying tangential velocities, suggesting that the coronal activity remains saturated with age. The authors do not find any break in the saturation-type relation at the spectral type at which stars become fully convective (~M3.5). Most of the stars in their sample show more coronal emission than the dMe stars in the Hyades and Praesepe clusters and have v_tan < 40 km s^-1, suggesting that they belong to a young population. This table was created by the HEASARC in March 2010 based on the (corrected) electronic version of Table 1 from the reference paper which was obtained from the Astronomical Journal web site. This is a service provided by NASA HEASARC .

This table contains the 5th Data Release Sloan Digital Sky Survey (DR5 SDSS)/XMM-Newton Quasar Survey Catalog. This catalog contains 792 SDSS DR5 quasars with optical spectra that have been observed serendipitously in the X-rays with XMM-Newton. These quasars cover a redshift range of z = 0.11 - 5.41 and a magnitude range of i = 15.3 - 20.7. Substantial numbers of radio-loud (70) and broad absorption line (51) quasars exist within this sample. Significant X-ray detections at >=2 sigma account for 87% of the sample (685 quasars), and 473 quasars are detected at >=6 sigma, sufficient to allow X-ray spectral fits. For detected sources, ~60% have X-ray fluxes between F(2-10 keV) = (1-10) x 10^-14 erg cm^-2 s^-1. The authors fit a single power law, a fixed power law with intrinsic absorption left free to vary, and an absorbed power-law model to all quasars with X-ray signal-to-noise ratio >= 6, resulting in a weighted mean photon index Gamma = 1.91 +/- 0.08, with an intrinsic dispersion sigma(Gamma) = 0.38. For the 55 sources (11.6%) that prefer intrinsic absorption, the authors find a weighted mean N_H = 1.5 +/- 0.3 x 10²¹ cm^-2. They find that Gamma correlates significantly with optical color, Delta(g-i), the optical-to-X-ray spectral index (alpha_ox), and the X-ray luminosity. While the first two correlations can be explained as artifacts of undetected intrinsic absorption, the correlation between Gamma and X-ray luminosity appears to be a real physical correlation, indicating a pivot in the X-ray slope. This table was created by the HEASARC in July 2009 based on electronic versions of Tables 1 and 2 from the paper which were obtained from the Astrophysical Journal web site. This is a service provided by NASA HEASARC .

Clusters of galaxies in most of the previous catalogs have redshifts z <= 0.3. Using the photometric redshifts of galaxies from the Sloan Digital Sky Survey Data Release 6 (SDSS DR6), the authors identify 39,716 clusters in the redshift range 0.05 < z < 0.6 with more than eight luminous (M_r <= -21) member galaxies. Cluster redshifts are estimated accurately with an uncertainty of less than 0.022. The contamination rate of member galaxies is found to be roughly 20%, and the completeness of member galaxy detection reaches ~90%. Monte Carlo simulations show that the cluster detection rate is more than 90% for massive (M_200 > 2 x 10¹⁴ M_sun, where M_200 is the total mass within the radius in which the mean mass density is 200 times the critical cosmic mass density) clusters of z <= 0.42. The false detection rate is ~5%. The authors obtain the richness, the summed luminosity, and the gross galaxy number within the determined radius for identified clusters. They are tightly related to the X-ray luminosity and temperature of the clusters. Cluster mass is related to the richness and summed luminosity with M_200 ~ R^{(1.90+/-0.04)} and M_200 ~ L_r^{(1.64+/-0.03)}, respectively. In addition, 790 new candidate X-ray clusters are found by cross-identification of these clusters with the source list of the ROSAT X-ray All-Sky Survey. This table was created by the HEASARC in August 2009 based on electronic versions of Tables 1 and 2 from the paper which were obtained from the Astrophysical Journal web site. This is a service provided by NASA HEASARC .

The COSMOS2015 catalogue contains precise photometric red-shifts and stellar masses for more than half a million objects over the 2 deg^2 COSMOS field. Including YJHKs images from the UltraVISTA-DR2 survey, Y-band from Subaru/Hyper-Suprime-Cam and infrared data from SPLASH Spitzer Legacy program, this near-infrared selected catalogue is highly optimised for the study of galaxy evolution and environments in the early Universe.

This table contains an all-sky catalog of M dwarf stars with apparent infrared magnitude J < 10. The 8889 stars are selected from the ongoing SUPERBLINK survey of stars with proper motion mu > 40 mas yr^-1, supplemented on the bright end with the Tycho-2 catalog. Completeness tests which account for kinematic (proper motion) bias suggest that this catalog represents ~75% of the estimated ~11,900 M dwarfs with J < 10 expected to populate the entire sky. The catalog is, however, significantly more complete for the northern sky (~90%) than it is for the south (~60%). Stars are identified as cool, red M dwarfs from a combination of optical and infrared color cuts, and are distinguished from background M giants and highly reddened stars using either existing parallax measurements or, if such measurements are lacking, using their location in an optical-to-infrared reduced proper motion diagram. These bright M dwarfs are all prime targets for exoplanet surveys using the Doppler radial velocity or transit methods; the combination of low-mass and bright apparent magnitude should make possible the detection of Earth-size planets on short-period orbits using currently available techniques. Parallax measurements, when available, and photometric distance estimates are provided for all stars, and these place most systems within 60 pc of the Sun. Spectral type estimated from V-J color shows that most of the stars range from K7 to M4, with only a few late M dwarfs, all within 20 pc. Proximity to the Sun also makes these stars good targets for high-resolution exoplanet imaging searches, especially if younger objects can be identified on the basis of X-ray or UV excess. For that purpose, we include X-ray flux from ROSAT and FUV/NUV ultraviolet magnitudes from GALEX for all stars for which a counterpart can be identified in those catalogs. Additional photometric data include optical magnitudes from Digitized Sky Survey plates and infrared magnitudes from the Two Micron All Sky Survey. This table was first created by the HEASARC in October 2011 based on electronic versions of Tables 1 and 2 from the reference paper which were obtained from the AJ web site. A slightly revised version based on corrected versions of the input tables received from the author was ingested in December 2011. This is a service provided by NASA HEASARC .