Bb 7b13, 3rd inversion (G# in the bass)
Also written as Bb7b13/G#.
Notes, from the bass up
G# (bass)F#A#DE#
The same notes as Bb 7b13 (G#, F#, A#, D and E#), rearranged so G# is the lowest note. Use it to move between chords with smaller jumps across the keyboard.