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Description
The moderately fast Nova Oph 2007 reached maximum brightness on 2007 March 28 at V=8.52, B-V=+1.12, V-Rc=+0.76, V-Ic=+1.59 and Rc-Ic=+0.83 , after fast initial rise and a pre-maximum halt lasting a week. Decline times were t^V^_2_=26.5, t^B^_2_=30, t^V^_3_=48.5 and t^B^_3_=56.5d. The distance to the nova is d=3.7+/-0.2kpc , the height above the Galactic plane is z=215pc, the reddening is E(B-V)=0.90 and the absolute magnitude at maximum is M^max^_V_=-7.2 and M^max^_B_=-7.0. The spectrum four days before maximum resembled a F6 supergiant, in an agreement with broad-band colours. It later developed into that of a standard 'FeII'-class nova. Nine days past maximum, the expansion velocity estiIIted from the width of H{alpha} emission component was ~730km/s, and the displacement from it of the principal and diffuse-enhanced absorption systems was ~650 and 1380km/s, respectively. Dust probably formed and disappeared during the period from 82 to 100d past maximum, causing (at peak dust concentration) an extinction of {Delta}B=1.8mag and an extra {Delta}E(B-V)=0.44 reddening.
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