C♯ major blues

C♯1D♯2E♭3E♯3G♯5A♯6

Major pentatonic with a flattened third added next to the third — the two live side by side rather than replacing each other.

The same sounds spelled from the other side are D♭ major blues.

Written out

Fig. 2 · C# major blues, ascending

Every accidental is written in, rather than left to a key signature, so the letters can be read one at a time.

C♯WD♯HEHE♯W+HG♯WA♯W+HC♯

C♯ major blues is C♯, D♯, E, E♯, G♯ and A♯, and back to C♯.

Its steps are W – H – H – W+H – W – W+H, where W is a whole step and H a half.

Across the first twelve frets of the guitar its notes fall in 38 places, which is what makes a scale a shape rather than a list.

Found by testing every chord in the catalogue against these 6 sounds, not chosen.