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ECH_LOCATE
Function
Locate order positions at frame central column.
Summary
This routine locates the centres of the orders in an echellogram.
The central xbox columns are then sampled using a box
scaled according to the expected order size. A triangle function
of appropriate dimension is then convolved with the array and
the resluting array is smoothed. A search is then made for the
local peak values representing the approximate order centres.
The central three columns of each order are examined and assumed
to be local peak intensities, the program then steps out above/below
each order until it reaches either: the next order, or a pixel
whose intensity falls below the threshold * peak intensity.
The 'threshold' being a tunable parameter (default 0.90 = 90%)
Available Topics
Martin Clayton
mjc@star.ucl.ac.uk
Mon Dec 9 17:09:35 1996