[Xastir] Multiple instances of Xastir

[N1OFZ]

I finally got aprsd running on my Linux box after some much appreciated 
help from Chuck (kg4ijb).  I now have xastir getting it's feed from 
aprsd.  I now want to run a second instance of xastir under a different 
user.  I set up the user but there is a problem when I try to start 
xastir.  I open a terminal window and do: sudo -c aprs1 xastir.  I get 
the error:  Xlib connection to "0:0" refused by server.  Xlib: No 
protocol specified.  Error: Can't open display :0.0.  I know this is a 
X11 issue but I hope since others have done this maybe they can shed 
some light on how to do this.

Thanks,
Dana
N1OFZ