.nf
/DEROTATOR angle system

Specify derotator angle for HERA

Real      :: angle             ! in units [deg] (!)
Character :: system            ! 

Choices for system:
"Nasmyth"       
"horizon"       
"equatorial"    
"frame"                        ! same as Nasmyth
"sky"                          ! same as equatorial

NOTES: The last 2 are for consistency with old control system and HERA conventions.
This option works only for RECEIVER HERA1 or RECEIVER HERA2 (of course it's the 
same angle for HERA1 and HERA2).
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