Bb Dominant 13th, 3rd inversion (G# in the bass)
Notes, from the bass up
G# (bass)B#D#GA#DE#
The same notes as Bb Dominant 13th (G#, B#, D#, G, A#, D and E#), rearranged so G# is the lowest note. Use it to move between chords with smaller jumps across the keyboard.