  The young sigma Orionis cluster is an indispensable basis for understanding
the formation and evolution of stars, brown dwarfs and planetary-mass objects.
Our knowledge of its stellar population is, however, incomplete. I present the
Mayrit catalogue, that comprises most of the stars and high-mass brown dwarfs
of the cluster. The basis of this work is an optical-near infrared correlation
between the 2MASS and DENIS catalogues in a circular area of radius 30 arcmin
centred on the OB-type binary sigma Ori AB. The analysis is supported on a
bibliographic search of confirmed cluster members with features of youth and on
additional X-ray, mid-infrared and astrometric data. I list 241 sigma Orionis
stars and brown dwarfs with known features of youth, 97 candidate cluster
members (40 are new) and 115 back- and foreground sources in the survey area.
The 338 cluster members and member candidates constitute the Mayrit catalogue.
This catalogue is a suitable input for studying the spatial ditribution,
multiplicity, properties and frequency of discs and the complete mass function
of sigma Orionis.

Astrophysics