The A sharp minor ninth chord is a 5-note chord consisting of the notes A#, C#, E#, G# and B#.
You can see these notes highlighted in the interactive piano chart below.
The chord itself is often abbreviated as A#m9.
Chords that are a superset of A#m9. The chords include more notes but always A#, C#, E#, G# and B#.
Chords that are a subset of A#m9. These contain less notes but all of them are included in A#m9.
In case you prefer a non-interactive variant of the chord chart, we've embedded a PNG image below that shows the notes for the the A#m9 chord. Feel free to save or share the image as needed.