OWENS is a FORTRAN77 program, using double precision arithmetic, which evaluates Owen's T function.
There is a mistake in the text of the routines, as printed in the Journal of Statistical Software. In particular, there is a mistake in the text of the function T(H,A), which has been corrected in the source code given here.
ASA005 is a FORTRAN77 library which evaluates the CDF of the noncentral T distribution, and uses Owen's T function.
ASA076 is a FORTRAN77 library which evaluates Owen's T function.
ASA243 is a FORTRAN77 library which evaluates the CDF of the noncentral T distribution.
OWENS is also available in a C++ version and a FORTRAN90 version and a MATLAB version
TEST_VALUE is a FORTRAN77 library which includes selected values of many special functions.
You can go up one level to the FORTRAN77 source codes.