Our main aim is the first detailed analysis of the two eclipsing binaries
V456 Oph and V490 Cyg. The system V456 Oph has been studied both
photometrically via an analysis of its light curve observed by the INTEGRAL/OMC
and by the period analysis of all available times of minima. V490 Cyg has been
studied by means of a period analysis only. Many new times of minima for both
systems have recently been observed and derived. This allows us for the first
time to study in detail the processes that affect both binaries. The main
result is the discovery that both systems have eccentric orbits. For V456 Oph
we deal with the eccentric eclipsing binary system with the shortest orbital
period known (about 1.016 day), while the apsidal motion period is about 23
years. V490 Cyg represents the eclipsing system with the shortest apsidal
motion period (about 18.8 years only). The two components of V456 Oph are
probably of spectral type F. We compare and discuss the V456 Oph results from
the light curve and the period analysis, but a more detailed spectroscopy is
needed to confirm the physical parameters of the components more precisely.Comment: 4 pages, 3 figures, published in A&A: 2011A&A...527A..43
