The Brera multi-scale wavelet Chandra survey^*

I. Serendipitous source catalogue

¹ INAF – Osservatorio Astronomico di Brera, via E. Bianchi 46, 23807 Merate (LC), Italy e-mail: romano@ifc.inaf.it
² INAF, Istituto di Astrofisica Spaziale e Fisica Cosmica, via U. La Malfa 153, 90146 Palermo, Italy
³ Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, Surrey, RH5 6NT, UK
⁴ European Southern Observatory, Schwarzschild Straße 2, 85740 Garching bei München, Germany

Received: 18 February 2008
Accepted: 21 May 2008

Abstract

We present the BMW-Chandra source catalogue drawn from essentially all Chandra ACIS-I pointed observations with an exposure time in excess of 10 ks public as of March 2003 (136 observations). Using the wavelet detection algorithm developed by Lazzati et al. (1999) and Campana et al. (1999), which can characterise both point-like and extended sources, we identified 21 325 sources. Among them, 16 758 are serendipitous, i.e. not associated with the targets of the pointings, and do not require a non-automated analysis. This makes our catalogue the largest compilation of Chandra sources to date. The 0.5–10 keV absorption corrected fluxes of these sources range from to  erg cm^-2 s^-1 with a median of  erg cm^-2 s^-1. The catalogue consists of count rates and relative errors in three energy bands (total, 0.5–7 keV; soft, 0.5–2 keV; and hard, 2–7 keV), and source positions relative to the highest signal-to-noise detection among the three bands. The wavelet algorithm also provides an estimate of the extension of the source. We include information drawn from the headers of the original files, as well, and extracted source counts in four additional energy bands, SB1 (0.5–1 keV), SB2 (1–2 keV), HB1 (2–4 keV), and HB2 (4–7 keV). We computed the sky coverage for the full catalogue and for a subset at high Galactic latitude (). The complete catalogue provides a sky coverage in the soft band (0.5–2 keV, ) of ~8 deg² at a limiting flux of  erg cm^-2 s^-1, and ~2 deg² at a limiting flux of  erg cm^-2 s^-1. Furthermore, we present the results of the cross-match with existing catalogues at different wavelengths (FIRST, IRAS, 2MASS, GSC2, and ChaMP). The total numbers of matches with the FIRST, IRASPSC, 2MASS, and GSC2 catalogues obtained after a closest-distance selection are 13, 87, 6700, and 4485, respectively.