<i>Chandra</i> Multiwavelength Project. I. First X‐Ray Source Catalog

Abstract

The Chandra Multi-wavelength Project (ChaMP) is a wide-area (~14 deg^2)\nsurvey of serendipitous Chandra X-ray sources, aiming to establish fair\nstatistical samples covering a wide range of characteristics (such as absorbed\nAGNs, high z clusters of galaxies) at flux levels (fX ~ 10^-15 - 10^-14 erg\nsec-1 cm-2) intermediate between the Chandra Deep surveys and previous\nmissions. We present the first ChaMP catalog, which consists of 991 near\non-axis, bright X-ray sources obtained from the initial sample of 62\nobservations. The data have been uniformly reduced and analyzed with techniques\nspecifically developed for the ChaMP and then validated by visual examination.\nTo assess source reliability and positional uncertainty, we perform a series of\nsimulations and also use Chandra data to complement the simulation study. The\nfalse source detection rate is found to be as good as or better than expected\nfor a given limiting threshold. On the other hand, the chance of missing a real\nsource is rather complex, depending on the source counts, off-axis distance (or\nPSF), and background rate. The positional error (95% confidence level) is\nusually &lt; 1" for a bright source, regardless of its off-axis distance while it\ncan be as large as 4" for a weak source (~20 counts) at a large off-axis\ndistance (Doff-axis &gt; 8'). We have also developed new methods to find spatially\nextended or temporary variable sources and those sources are listed in the\ncatalog.\n