Tautomerism in 10-(hy­droxy­imino)­phenanthren-9-one

In the title compound, C₁₄H₉NO₂, a static disorder exists between the keto–oxime and hy­droxy–nitroso tautomers, in an approximate ratio of 4.6:1, based on refined occupancies for disordered parts. No inter­molecular hydrogen bonding is present in the crystal structure. Instead, both tautomers exhibit similar intra­molecular O—H...O hydrogen bonds.