piano scale
G♯ Mixolydian
G♯1A♯2B♯3C♯4D♯5E♯6F♯♭7
Major with a flattened seventh: the scale that fits a dominant seventh chord without altering it.
The same sounds spelled from the other side are A♭ Mixolydian.
Written out
Every accidental is written in, rather than left to a key signature, so the letters can be read one at a time.
The step pattern
G♯WA♯WB♯HC♯WD♯WE♯HF♯WG♯
What is true of it
G♯ Mixolydian is G♯, A♯, B♯, C♯, D♯, E♯ and F♯, and back to G♯.
Its steps are W – W – H – W – W – H – W, where W is a whole step and H a half.
It costs 7 alterations to write — near the limit of what a key signature can carry.
On the same tonic, G♯ major differs from it by exactly one note.
Chords made only of these notes
C♯majorC♯maj7major seventhD♯mminorD♯m7minor seventhF♯majorF♯maj7major seventhG♯majorG♯7dominant seventh
Found by testing every chord in the catalogue against these 7 sounds, not chosen.