% @(#)locatemos.hlq	1.4 (ESO-DMD) 2/14/94 14:52:53
%++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
%.COPYRIGHT  (c)  1994 European Southern Observatory
%.IDENT      locatemos.hlq
%.AUTHOR     PB, DMD/ESO
%.KEYWORDS   MIDAS, help files, LOCATE/MOS
%.PURPOSE    On-line help file for the command: LOCATE/MOS
%.VERSION    1.0  14-FEB-1994 : Creation, PB
%----------------------------------------------------------------
\se
SECTION./MOS
\es\co
LOCATE/MOS					19-AUG-1993 OS
\oc\su
LOCATE/MOS [ff] [thresh,width,low_limit] [table] [x-position,x-width]
	locates slitlets in MOS flat-field frame 
\us\pu
Purpose:   
	  find slitlet positions in MOS flat-field frame
\up\sy
Syntax:
	  LOCATE/MOS [ff] [thresh,width,low_limit] [table] [x-position,x-width] [nml]
\ys\pa
	  ff = Flat-field image. 
              Session keyword: FLAT
              Default: flat
	  thresh    = threshold for slitlet detection.
          width     = width of the slitlet edges
          low_limit = lower limit for valid slitlets
	      Session keyword: FLATLIM
              Default: 0,0,0
	  table = Output table with slitlet positions. 
	      Session keyword: MOS
              Default: mos
          x-position = mean x-position of trace through the slitlets
          x-width    = width of trace 
              Session keyword: SCAN_POS
              Default: 0,0
	  nml = "no mans land": number of pixels at the edge of the slitlets 
		that shall be ignored
	      Default: 2
\ap\sa
See Also: 
	  DEFINE/SLIT, PLOT/LOCATE
\as\no
Note:       
	  This command locates the slitlets in an MOS flat-field frame
	  by searching for the maximum (normalized) gradient in a trace 
          perpendicular to the direction of dispersion. The result is written 
          to the output table MOS. This table is used by most MOS commands.
          If the algorithm does not find any slitlets the chosen threshold 
          may either be too high (above the intensity of the flats in the 
          center of the frame) or too low (below bias value). Also, the width
          may be chosen to high or too small.
\on\exs
Examples:
\ex
           LOCATE/MOS domeflat 0.2,5,50 mos 500,20
           Tries to locate slitlets by looking for gradients in 
           a trace through the frame domeflat.bdf at x-position 480-520.
           Gradients must exceed 0.2 (20 %) within two pixel. The trace is
           median filtered with 5 pixel width to avoid spurious 
           detections. Pixel values below 50 ADU are not considered valid.
           The resulting limits are stored in the table given by keyword MOS.
\xe \sxe