I'm not sure about the old cable I found. It is 4pin RJ plug to male DB9 (pins 5,8,2).
This is different o the one for my CGEM which is 4pin RJ plug to female DB9 pins 5,3,2). As per
https://www.nexstarsite.com/PCControl/RS232Cable.htm
I'm not sure if this is correct for the AS-GT mount??? If it is you can have it. But it might be safer to buy one