Activity in low-mass stars is an important ingredient in the evolution of
such objects. Fundamental physical properties such as age, rotation, magnetic
field are correlated with activity. Aims: We show that two components of the
low-mass triple system LHS 1070 exhibit strong flaring activity. We identify
the flaring components and obtained an improved astrometric solution for the
LHS 1070 A/(B+C) system. Methods: Time-series CCD observations were used to
monitor LHS 1070 in the B and I_C bands. H-band data were used to obtain
accurate astrometry for the LHS 1070 A/(B+C) system. Results: We have found
that two components of the triple system LHS 1070 exhibit photometric activity.
We identified that components A and B are the flaring objects. We estimate the
total energy, ~2.0 x 10^{33} ergs, and the magnetic field strength, ~5.5 kG, of
the flare observed in LHS 1070 B. This event is the largest amplitude, \Delta B
> 8.2 mag, ever observed in a flare star.Comment: 5 pages, 5 figures, accepted for publication in A&
