McDonald Observatory is not supported at a level to provide an Instrument Scientist as seen at National Astronomical Facilities. Due to the limited resources and few astronomically trained staff at the mountain, the members of the Observing Support Group are only trained in the setup, checkout, basic operation of instruments, and not in their astronomical usage. Observing support covers three basic areas (hardware and control electronics, control and acquisition software, and optical setup and alignment.). 

Instruments are divided into two classifications as defined by the level of their on-site operational support by the Observatory staff:
(1) Facility Instruments are completely supported by the Observing Support Group; and
(2) PI Instruments supported by a Principal Investigator (PI) possibly with some assistance from the Observing Support Group. 

Facility Instruments are instrumental systems that have matured and most of the Observing Support staff is qualified to setup, checkout and carryout basic operations. Most of the Facility Instruments have an astronomer who is a long time user and who oversees the development of scientific operation manuals and checkout procedures, but does not reside at the Observatory. These astronomers are listed as the Scientist on the web based instrument description pages and are the astronomically trained contact for the instrument. New users of a Facility Instrument are expected to become qualified users by observing with another qualified user and the observatory support staff. 

PI Instruments are instrumental systems which have been developed by the designated Principal Investigator on the web based instrument description pages. The procedures for operating these instruments may not have matured and are know primarily to the PI and their group. A PI Instrument has not been turned over to the Observatory for general use. These instruments can only be used by the PI or someone he/she designates as a qualified user. Usually some portion of the setup, checkout, and operational procedures requires special knowledge and skills held only by the PI. Users wishing to use a PI instrument must request approval from the PI prior to proposing for time.