Photometric study of ultracool dwarfs and M dwarfs: preliminary results

We present preliminary results of V, R, I photometric observations of 7 late type dwarfs of spectral types from M4 to T7. These dwarfs have little or no previous optical photometric studies and are part of a long-term program studying the activity at the bottom of the Main Sequence and the brown dwarf regime. We have obtained R and I magnitudes for all 7 dwarfs as well as V magnitudes for 3 of them. This is the first step towards characterization of their photometric properties and monitoring for variability which in turn will give us information of the physical nature of their atmospheres.