B#13 chord

The B-sharp dominant thirteenth chord (abbreviated "B#13 chord") is a seven-note chord consisting of the notes B♯, D, F, A♯, C, E♯, and G. The chord is formed by adding a thirteenth to a B-sharp dominant eleventh chord.

In practice, the fifth (F) and eleventh (E♯) are often omitted from the B#13 chord to avoid a very dissonant sound, and because it's not always possible to play all notes simultaneously.