piano chord
F♯add9
F♯1A♯3C♯5G♯9
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 G♭add9 — the same twelve keys on a piano, a different piece of notation.
What is true of it
F♯add9 is F♯, A♯, C♯ and G♯ — 1, 3, 5 and 9 counted from F♯.
On an instrument that cannot reach all 4, the 5 goes first, in that order.