### ECH_COLLIMATOR

Determine which collimator to use at a given wavelength

##### Description

If a central wavelength is given, use the WIDE collimator for wavelengths longer than 4000 Angstroms and the UV collimator otherwise. Otherwise make the decision based on whether gamma is greater or less than 0.1369 degrees. For UCLES, this value of gamma corresponds a central wavelength of very close to 4000 Angstroms.

##### Invocation

CALLECH_COLLIMATOR (WAVE, GAMMA,COLOUR, STATUS)

##### Arguments
 READ WAVE REAL Central wavelength of detector. If specified as <= 0, is not used (Angstroms) READ GAMMA REAL Echelle gamma angle corresponding to the current configuration. Is used only if WAVE is <= 0 (radians) WRITE COLOUR CHARACTER The optimal collimator, either WIDE or UV READ, WRITE STATUS INTEGER Global status value
##### Bugs

The algorithm is too simplistic. It should take account of the detector size and guarantee that the best choice of collimator is made for the whole detector rather than just for its centre (although this is rather hard without knowledge of the configuration history!).

##### Authors

C.J. Hirst UCL (ZUVAD::CJH)