C#13 chord

The C-sharp dominant thirteenth chord (abbreviated "C#13 chord") is a seven-note chord consisting of the notes C♯, E♯, G♯, B, D♯, F♯, and A♯. The chord is formed by adding a thirteenth to a C-sharp dominant eleventh chord.

In practice, the fifth (G♯) and eleventh (F♯) are often omitted from the C#13 chord to avoid a very dissonant sound, and because it's not always possible to play all notes simultaneously.