Notes: C, Db, Eb, F, G, Ab, and Bb - Key: C - Category: Octatonic Scales
The C Deuterus authenticus 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 four black keys: Db, Eb, Ab, and Bb and three white keys: C, F, and G. 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 Deuterus authenticus Scale we can find it has four flats and no sharps. Therefore, on sheet music you will find four accidentals on the score. The notes of this scale are: C, Db, Eb, F, G, Ab, and Bb.