Chandra Multiwavelength Project. I. First X‐Ray Source Catalog

The Chandra Multi-wavelength Project (ChaMP) is a wide-area (~14 deg^2)survey of serendipitous Chandra X-ray sources, aiming to establish fairstatistical samples covering a wide range of characteristics (such as absorbedAGNs, high z clusters of galaxies) at flux levels (fX ~ 10^-15 - 10^-14 ergsec-1 cm-2) intermediate between the Chandra Deep surveys and previousmissions. We present the first ChaMP catalog, which consists of 991 nearon-axis, bright X-ray sources obtained from the initial sample of 62observations. The data have been uniformly reduced and analyzed with techniquesspecifically developed for the ChaMP and then validated by visual examination.To assess source reliability and positional uncertainty, we perform a series ofsimulations and also use Chandra data to complement the simulation study. Thefalse source detection rate is found to be as good as or better than expectedfor a given limiting threshold. On the other hand, the chance of missing a realsource is rather complex, depending on the source counts, off-axis distance (orPSF), and background rate. The positional error (95% confidence level) isusually < 1" for a bright source, regardless of its off-axis distance while itcan be as large as 4" for a weak source (~20 counts) at a large off-axisdistance (Doff-axis > 8'). We have also developed new methods to find spatiallyextended or temporary variable sources and those sources are listed in thecatalog.