Austrian maker marks

Hi!

I’m new here. I was researching a small spoon that had some marks. I could identify the “Viennese cross shield” but the other mark (makers mark?) is something else. I wasn’t able to pin point who made it. My asumption is that it reads “AST”.

If anyone can help me with this one I would be very grateful!!

Hallmarks of Austrian silver 1737 - 1921

1811/1866, A=Vienna, 13 loth = 812/1000.