A Augmented Major 7th, 1st inversion (C# in the bass)
Also written as Aaug(maj7)/C#.
Notes, from the bass up
C# (bass)E#G#A
The same notes as A Augmented Major 7th (C#, E#, G# and A), rearranged so C# is the lowest note. Use it to move between chords with smaller jumps across the keyboard.