Notes: C, D, E, F#, G, A, and Bb - Key: C - Category: Octatonic Scales
The C Overtone uses eight notes per octave. Because of this same reason it is a member of the so called Octatonic -scales that have Eight-note (or Eight-tone). On the piano keyboard, it is made up of two black keys: F#, and Bb and five white keys: C, D, E, G, and A. This combination makes this scale - as well as the C Prometheus, C Prometheus Liszt, and C Prometheus Neapolitan - as great choices for composing or improvising music.
If we take a look a the key signature of the C Overtone Scale we can find it has one flats and one sharps. Therefore, on sheet music you will find two accidentals on the score. The notes of this scale are: C, D, E, F#, G, A, and Bb.