The term Automatic Telescope (AT) will be used in this document to refer to any telescope which can be pointed under computer control, the telescope control computer, and the associated instruments which are also under computer control. The term telescope is not restricted to optical telescopes, although instructions for non-optical telescopes have not been included in this version of the standard. It is the AT's responsibility to execute the instructions which it receives that are within the capabilities of the telescope and instrument. The AT software is expected to reject any instructions which could damage the telescope or instrument or are outside of its capabilities and to continue with acceptable operation.
The term Principal Astronomer (PA) is commonly used to refer to the person responsible for an astronomical project. In ATIS, the PA is the human responsible for the proper operation of an automatic telescope. The PA is responsible for scheduling the telescope's time, arbitrating users' requests for observations when there are conflicts, and trying to insure that the AT is meeting whatever objectives have been set forth for its operation. The PA may have the additional requirement of assuring the performance of the telescope by scheduling measurement of standard objects and other specialized test measurements.
The term User is used to refer to the persons who originate requests for observations on an AT. The user is usually the ultimate recipient of the data from an AT, either in raw or reduced form. It is assumed that a user also has computers and the term "user" includes the user's computer. The user has the responsibility to determine the science to be accomplished, to decide on appropriate observations required to accomplish the scientific objectives, to analyze the data, and to archive the data received from the ATs.
The term Principal Astronomer's Computer (PAC) is used in ATIS to refer to the computer, under the supervision of the PA, which generates ATIS files to be sent to an AT and receives the files generated by an AT. Additional tasks may include transmission of the data, automatic reception of requests from users, scheduling optimization, data reduction, performance monitoring, and transmission of results to users.
The term Network Principal Astronomer (NPA) and the associated Network Principal Astronomer's Computer (NPAC) are used to refer to a human and the associated computers which coordinate observations between various PAs. This arrangement is used for networks of automatic telescopes. Network PAs are a lot like users in that they are not directly responsible for the operation of any particular telescope. The mission of an NPAC is to coordinate observing time between various PA/PACs in order to archive the goals of networks of users.
The terms above only refer to functions and not to specific people or computers. The same computer could, for example, be both a PAC and an AT controller. A PA may also be a user. A PAC or NPAC could consist of many computers.
ATIS files link users to PACs, PACs to ATs, and PACs to NPACs. In other words, ATIS may be used for transmitting requests for observations from users to the computer of the astronomer responsible for a given telescope, for sending reduced data back to the users, for the communications between the principal astronomer and the telescope, and for networking between telescopes through network control centers.
ATIS is not software, but software is required at all stages to handle ATIS files. Users are encouraged to share software for all areas of ATIS including user file generation, schedulers, telescope control, data reduction, FITS image manipulation and reduction, data analysis, and accounting. Appendix A contains a list of accessible sources of this document in machine readable form and software related to ATIS and items of general interest for automated telescope operation.