The A-sharp dominant seventh flat five chord (abbreviated "A#7(b5) chord") is a four-note chord consisting of the notes A♯, C, E, and G♯. The chord is formed by lowering the fifth of a A-sharp dominant seventh chord a half step.
A-sharp dominant seventh flat five chord
A♯ C E G♯
1 3 ♭5 ♭7
Tetrad (four-note chord)