piano chord
A♯m7♭5
A♯1C♯♭3E♭5G♯♭7
A diminished triad with a minor seventh rather than a diminished one — half diminished, and not the same chord as dim7.
Written the other way round it is B♭m7♭5 — the same twelve keys on a piano, a different piece of notation.
What is true of it
A♯m7♭5 is A♯, C♯, E and G♯ — 1, b3, b5 and b7 counted from A♯.
These are also the notes of C♯m6/A♯ and D♭m6/A♯. Which name is right depends on what is underneath and what came before — the notes alone do not decide.