The A sharp dominant seventh chord is a 4-note chord consisting of the notes A#, C##, E# and G#.
You can see these notes highlighted in the interactive piano chart below.
The chord itself is often abbreviated as A#7.
Chords that are a superset of A#7. The chords include more notes but always A#, C##, E# and G#.
Chords that are a subset of A#7. These contain less notes but all of them are included in A#7.
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#7 chord. Feel free to save or share the image as needed.