Storing sexagesimal angles

Columns of angles may be stored formatted as sexagesimal hours or degrees or as minutes or seconds of arc or time in an STL catalogue. These options both make the catalogues much easier to read by eye and allow STL descriptions to be prepared for many existing catalogues which are held as text files.

The TBLFMT item for a column in a catalogue is usually the Fortran 77 format specifier to read the column (see Section  above). However, it has some special values to describe sexagesimal angles. These special values divide into two categories, one suitable for simple angles and the other covering more complex cases. In a simple angle a colon (`:') is used to separate the sexagesimal components. For complex angles the separator can be a space, or any other character, or indeed there may be no separator at all. The facilities for complex angles can handle most of the formats used in practice to represent angles in astronomical catalogues formatted as text files. The simple and complex options are described separately below.