SHORT_TOLE
REAL value of the tolerance in position (in radians). The behaviour differs
for Short and Zero spacings and Table or 3-D cubes as Single-Dish data.
If the Single-Dish data is a table of spectra, Spectra differing by less
than this amount will be added together prior to gridding. A recommended
value is below 1/10th of the Single Dish primary beam. This is valid for
Short Spacings and Zero Spacing cases.
If the Single-Dish data is 3-D data cube, SHORT_TOLE is used only for Zero
Spacings. If no pixel is within SHORT_TOLE of an Interferometer pointing
center, no short spacing is added for this field and an error occurs.
Default value is 0, meaning using 1/16th of the Single Dish primary beam.