% @(#)fit_ell1.hlq	17.1.1.1 (ESO-IPG) 01/25/02 17:18:47 
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SECTION./ELL1
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FIT/ELL1                                                        14-Mar-1991 RHW
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FIT/ELL1 inframe outframe l_iso,h_iso x_cen,y_cen max_rad
	fit an ellips with respect to predefined center
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Purpose:     An image is searched for intensity points within a certain
             intensity range and within a radius to the center.
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Syntax:      FIT/ELL1 inframe outframe l_iso,h_iso x_cen,y_cen max_rad
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             inframe       = input frame
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             outframe      = output frame with isophotal points and fitted
                             ellipse
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             l_iso,h_iso   = low and high isophotal levels
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             x_cen,y_cen   = x and y centre in world coordinates
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             max_rad       = radius around center to be surveyed; default is
                             value used in the previous run
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Note:        The ellipse centre (x and y), the semi-major diameter, the 
             semi-minor diameter and the position angle (degrees, o on 
             positive x axis increasing to positive y axis) will be saved in
             the descriptor ELLPAR attached to the output frame.
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             The maximum survey radius should be slightly larger than the 
             semi-major diameter of the fitted ellipse - a too large survey
             diameter of the fitted ellipse includes to many spurious pixels
             at large distances, producing a too large (and round) fitted 
             ellipse.
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See also:    LOAD/IMAGE
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Examples:
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             FIT/ELL1 INFRAME FITFRAM 1,5 98.5,101.1 20
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