We present an RI photometric survey covering an area of 430 arcmin ^ { 2 } around the multiple star \sigma Orionis .
The observations were conducted with the 0.8 m IAC-80 Telescope at the Teide Observatory .
The survey limiting R and I magnitudes are 22.5 and 21 , and completeness magnitudes 21 and 20 , respectively .
We have selected 53 candidates from the I vs . R – I 
colour-magnitude diagram ( I = 14–20 ) that follow the previously known photometric sequence of the cluster .
Adopting an age of 2–4 Myr for the cluster , we find that these objects span a mass range from 0.35 M _ { \odot } to 0.015 M _ { \odot } .
We have performed J -band photometry of 52 candidates and K _ { s } photometry for 12 of them , with the result that 50 follow the expected infrared sequence for the cluster , thus confirming with great confidence that the majority of the candidates are bona fide members . JHK _ { s } photometry from the Two Micron All Sky Survey ( 2MASS ) is available for 50 of the candidates and are in good agreement with our data .
Out of 48 candidates , which have photometric accuracies better than 0.1 mag in all bands , only three appear to show near-infrared excesses .