B#7(b9) chord
The B-sharp dominant minor ninth chord (abbreviated "B#7(b9) chord") is a five-note chord consisting of the notes B♯, D, F, A♯, and C♯. The chord is formed by adding a major ninth to a B-sharp dominant seventh chord.
In practice, the fifth (F) is often omitted from the B#7(b9) chord because it's not always possible to play all notes simultaneously.
Name
B-sharp dominant minor ninth chord
Notes
B♯ D F A♯ C♯
Intervals
1 3 5 ♭7 ♭9
Chord symbol
B♯7(b9)
Alternative symbol
B♯7b9
Type
Pentad (five-note chord)