BVRI observations of PSR B0656+14 with the 6-meter telescope

We observed the middle-aged radio pulsar B0656+14 with a CCD detector at the 6-m telescope. Broadband BVRI images show the following magnitudes of the pulsar counterpart: B = 24.85(+0.19,-0.16), V = 24.90(+0.16,-0.14), R = 24.52(+0.12,-0.11), I = 23.81(+0.27,-0.21). We fitted the UV-optical (space + ground-based) data with a two-component model which combines a power law (non-thermal component) with a thermal spectrum emitted by the neutron star surface. The power law component, with the energy power-law index α = 1.5(+1.1,-1-2), dominates in the observed range. Constraints on the thermal component correspond to the RayleighJeans parameter G = T₆(R₁₀/d₅₀₀)² = 4.1(+2.1,-4.1), where T = 10⁶T₆ K is the brightness temperature, R∞ = 10R₁₀ km is the neutron star radius as seen by a distant observer, and d = 500d₅₀₀ pc is the distance. The shape of the optical-UV spectrum of PSR B0656+14 differs considerably from those observed from other pulsars: the middle-aged Geminga and young Crab, Vela.