guitar chord
A♯add9
A major triad with a ninth added and no seventh — which is what tells it apart from a ninth chord.
Written the other way round it is B♭add9 — the same twelve keys on a piano, a different piece of notation.
Every fingering that fits a hand
x10311
moderate
x1031x
open · no 5
63036x
hard
63056x
hard
63033x
hard · no 5
What is true of it
A♯add9 is A♯, C𝄪, E♯ and B♯ — 1, 3, 5 and 9 counted from A♯.
C𝄪 is a double sharp, and it has to be: every letter from A♯ upwards is used once, so the 3 cannot be written any other way.
On an instrument that cannot reach all 4, the 5 goes first, in that order.
The easiest of the 5 fingerings below is x10311: 4 fingers, held at the 1st fret.
1 of them use open strings, which is what makes a shape quiet to change to.
1 string stays silent.
Where its notes are on the neck
The brass dots are A♯, the root. Everything else is a chord tone with its degree printed in it.
With a different note underneath
A♯add9/C𝄪
xx0311
A♯add9/E♯
11031x
A♯add9/B♯
x3333x
An inversion is the same chord with a different note lowest. The name changes to a slash name because the bass is what a listener hears as the foundation.