1 # Tests the Meqtree ParAngle (Parallactic Angle) node
   2 # Copyright: The MeqTree Foundation
   3 
   4 # standard preamble
   5 from Timba.TDL import *
   6 from Timba.Meq import meq
   7 from Timba.Meq import meqds
   8 
   9 # Timba.TDL.Settings.forest_state is a standard TDL name.
  10 # This is a record passed to Set.Forest.State.
  11 Settings.forest_state.cache_policy = 100;
  12 
  13 def _define_forest (ns):
  14   """define_forest() is a standard TDL name. """;
  15 # set up a sequence of nodes for testing of the ParAngle node
  16 
  17 # first define an RA and DEC (in radians)
  18   ra = 0.0
  19   dec = 0.0
  20   ns.ra0 << Meq.Parm(ra,node_groups='Parm')
  21   ns.dec0 << Meq.Parm(dec,node_groups='Parm')
  22 
  23 # then create a MeqComposer containing ra dec children
  24   ns.RADec <<Meq.Composer(ns.ra0, ns.dec0)
  25 
  26 
  27 # station positions ITRF X,Y,Z for 'pseudo' VLA telescope 
  28 # for aips++ MVDirection object (units are metres).
  29   X_pos = -1597262.96
  30   Y_pos = -5043205.54
  31   Z_pos = 3554901.34
  32   ns.x_pos << Meq.Parm(X_pos,node_groups='Parm')
  33   ns.y_pos << Meq.Parm(Y_pos,node_groups='Parm')
  34   ns.z_pos << Meq.Parm(Z_pos,node_groups='Parm')
  35 
  36 # create a  MeqComposer containing X_pos, Y_pos, Z_pos children
  37   ns.XYZ <<Meq.Composer(ns.x_pos, ns.y_pos, ns.z_pos)
  38 
  39 # we should now be able to create an ParAngle node with X,Y,Z station positions
  40   ns.ParAngle << Meq.ParAngle(radec=ns.RADec, xyz=ns.XYZ)
  41 
  42 # Note: you could also use an observatory name
  43 # ns.ParAngle1 << Meq.ParAngle(radec=ns.RADec, observatory = 'VLA')
  44 
  45 
  46 def _test_forest (mqs,parent):
  47   """test_forest() is a standard TDL name. """;
  48 
  49 ####
  50 # time and frequency domain
  51 # time - cover one day
  52   t0 = 0.01;
  53   t1 = 86400.01;
  54 
  55 # any old frequency
  56   f1 =  299792458.0;
  57   f0 = 0.9*f1;
  58 
  59 ####
  60 # Make cells array - we will compute Parallactic Angle over a period
  61 # of one day divided into 120 segments
  62 
  63   cells = meq.cells(meq.domain(f0,f1,t0,t1),num_freq=1,num_time=120);
  64 
  65 # define request
  66   request = meq.request(cells,rqtype='e1')
  67 
  68 # execute request
  69   a = mqs.meq('Node.Execute',record(name='ParAngle',request=request),wait=True);
  70 
  71 # The following is the testing branch, executed when the script is run directly
  72 # via 'python script.py'
  73 if __name__ == '__main__':
  74   Timba.TDL._dbg.set_verbose(5);
  75   ns = NodeScope();
  76   _define_forest(ns);
  77   # resolves nodes
  78   ns.Resolve();