Data Acquisition software is mostly written in C. There are also a lot of Bourne Shell scripts (intepreted by GNU bash.)
C++ has been used in Director and RPM.
QSO User Tools are implemented in Java.
Astronomers are starting to use a lot of Python. If they intend their Python to eventually be used as real-time analysis during data acquisition, it is requested that they use Python 2.7.9, and limit the modules and extensions they use to the versions present on our current sessionhost, alakai. I.e., they can develop code where ever they like, but test it on a machine like alakai, such as the software development host mohala (which is identical to alakai at the summit.)