A#9 chord
The A-sharp dominant ninth chord (abbreviated "A#9 chord") is a five-note chord consisting of the notes A♯, C, E♯, G♯, and B♯. The chord is formed by adding a major ninth to a A-sharp dominant seventh chord.
In practice, the fifth (E♯) is sometimes omitted from the A#9 chord because it's not always possible to play all notes simultaneously.
Name
A-sharp dominant ninth chord
Notes
A♯ C E♯ G♯ B♯
Intervals
1 3 5 ♭7 9
Chord symbol
A♯9
Type
pentad (five-note chord)