TUNE_TWTHR

Type: _REAL
The 'trace-width-threshold' is provided for cases when the S/N of the frame being examined to locate the orders is very low.

The threshold is the degree to which off-trace pixels must fall below the pixel at trace centre (in the spatial direction) in order to be considered as 'off-order'. I.e., the trace width is estimated by stepping pixel-by-pixel above and below the trace until the intensity falls below (1.0 - TUNE_TWTHR) x intensity-at-trace-centre.

The default value is 0.95 (95%).