The moderately fast Nova Oph 2007 reached maximum brightness on March 28 , 2007 at V =8.52 , B - V =+1.12 , V - R _ { C } =+0.76 , V - I _ { C } =+1.59 and R _ { C } - I _ { C } =+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 } =56.5 days .
The distance to the nova is d =3.7 \pm 0.2 kpc , the height above the galactic plane z =215 pc , the reddening E _ { B - V } =0.90 and the absolute magnitude at maximum M _ { V } ^ { max } = - 7.2 and M _ { B } ^ { max } = - 7.0 .
The spectrum four days before maximum resembled a F6 super-giant , in agreement with broad-band colors .
It later developed into that of a standard ’ FeII ’ -class nova .
Nine days past maximum , the expansion velocity estimated from the width of H \alpha emission component was \sim 730 km/s , and the displacement from it of the principal and diffuse enhanced absorption systems were \sim 650 and 1380 km/s , respectively .
Dust probably formed and disappeared during the period from 82 to 100 days past maximum , causing ( at peak dust concentration ) an extinction of \Delta B =1.8 mag and an extra \Delta E _ { B - V } =0.44 reddening .