A new catalogue of polar-ring galaxies selected from the SDSS. ?

Galaxies with polar rings (PRGs) are a unique class of extragalactic objects allowing to investigate a wide range of problems, linked with the formation and evolution of galaxies, and to study the properties of their dark haloes. The progress in the study of PRGs is constrained by a small number of known objects of this type. Whitmore et al. (1990) compiled a catalogue and photographic atlas of PRGs and related objects that included 157 galaxies. Up to date, we can only attribute about two dozens of kinematically-conflrmed galaxies to this class, mostly from this catalogue. We present a new catalogue of PRGs, supplementing the catalogue of Whitmore et al. (1990), and signiflcantly increasing the number of known candidate PRGs. The catalogue is based on the results of the original Galaxy Zoo project, under which the volunteers performed a visual classiflcation of nearly a million galaxies from the SDSS. Based on the preliminary classiflcation of the Galaxy Zoo, we viewed more than 40000 images of the Sloan Digital Sky Survey (SDSS) and selected 275 galaxies, included in our catalogue. Our Sloan-based Polar Ring Catalog (SPRC) contains 70 galaxies that we classifled as \the best candidates", among which we expect to have a very high proportion of true PRGs, and 115 good PRG candidates. 53 galaxies are classifled as PRG related objects (mostly, the galaxies with strongly warped discs, and mergers). In addition, we identifled 37 galaxies that have their presumed polar rings strongly inclined to the line of sight (seen almost face-on). The SPRC objects are on the average fainter and located further away than the galaxies from the catalog by Whitmore et al. (1990), although our catalogue does include dozens of new nearby candidate PRGs. The new catalogue signiflcantly increases the number of genuine PRG candidates, and may serve as a good basis both for the further detailed study of individual galaxies, and for the statistical analysis of PRGs as a separate class of objects. We performed spectroscopic observations of six galaxies from the SPRC at the 6m BTA telescope. The existence of polar rings was conflrmed in flve galaxies, and one object appeared to be a projection of a pair of galaxies. Adding the literature data, we can already classify 10 galaxies from our catalogue to the kinematically-conflrmed PRGs.