[evla-sw-discuss] Reference pointing

[Barry Clark]

Since Ken now has an Antsol working outside the Modcomps, I've
started thinking about how I'd like to implement reference pointing.
As it looks from the script at an antenna level:

x = RefPointing(<antenna id>)
y = RefPointing(x)   // loads y with the values extracted from x
refPointingAgent.register(x)
antenna.setRefPointing(x)

At the more common subarray level:

z = subarray.refPointingInit()
w = subarray.refPointingInit(z)  // copies previous values
refPointingAgent.register(z)
subarray.setRefPointing(z)
subarray.setRefPointing(none)    // to turn off reference pointing

The refPointingAgent.register() routine will cause the refPointing
object(s) to receive a new pointing offset exactly once.  For
"double reference pointing" one would insert a small, non-pointing,
scan between the two pointing scans to ensure that the solved values
from the first pointing scan are computed and in use before starting 
the second.

So usual sequence might be
z = subarray.refPointingInit()
subarray.setRefPointing(z)
< pointing scan at 3.6cm>
refPointingAgent.register(z)
< 20 second dummy scan to get organized >
< pointing scan at 7mm>
refPointingAgent.register(z)
< target scan at 7mm>
< pointing scan at 7mm>
refPointingAgent.register(z)
< target scan at 7mm>
etc...