ChandraMultiwavelength Plane (ChaMPlane) Survey: An Introduction

We introduce the Chandra Multiwavelength Plane (ChaMPlane) Survey, designedto measure or constrain the populations of low-luminosity (Lx > ~10^31 erg/s)accreting white dwarfs, neutron stars and stellar mass black holes in theGalactic Plane and Bulge. ChaMPlane incorporates two surveys, X-ray (Chandra)and optical (NOAO 4m-Mosaic imaging), and a followup spectroscopy and IRidentification program. The survey has now extended through the first 6 yearsof Chandra data using serendipitous sources detected in 105 distinct ACIS-I and-S fields observed in 154 pointings and covered by 65 deep Mosaic images in V,R, I, and H-alpha. ChaMPlane incorporates fields with galactic latitude |b| <~12 deg and selected to be devoid of bright point or diffuse sources, withexposure time > ~20 ksec, and (where possible) minimum NH. We describe thescientific goals and introduce the X-ray and optical/IR processing anddatabases. We derive preliminary constraints on the space density or luminosityfunction of cataclysmic variables from the X-ray/optical data for 14 fields inthe Galactic Anticenter. The lack of ChaMPlane CVs in these Anticenter fieldssuggests their space density is ~ 3x below the value (3 x 10^-5 pc^-3) foundfor the solar neighborhood by previous X-ray surveys. Companion papers describethe X-ray and optical processing in detail, optical spectroscopy of ChaMPlanesources in selected Anticenter fields and IR imaging results for the GalacticCenter field. An Appendix introduces the ChaMPlane Virtual Observatory (VO) foronline access to the X-ray and optical images and source catalogs for readydisplay and further analysis.Comment: 10 pages, 7 figures, 2 tables, accepted in ApJ for publicatio