Introduction

The function of the FCRAO tracking programs is to:

1. Point the telescope and control the other instruments.
2. Provide an interface to the observer.
3. Coordinate instrument control and the various data collection programs.

These tasks are achieved by a collection of programs which run in a coordinated fashion. The principal programs which are run as a part of the tracking programs are:

TRACK -

the program which actually monitors the telescope position and tracks celestial sources.

UPDATE -

a program which monitors various system parameters and updates ones which vary with time (such as the time itself).

SCREEN -

the program which writes tracking program information on the VT100 screen (and a remote observer's screen if present).

OPCOM -

the program which accepts input from the user at the command terminal in the control room, from the telescope platform terminal or from a remote user. OPCOM is only active when called for by the user for command input.

From the point of view of the observer, these tasks constitute a single logical task with the functions outlined above. The individual programs share a common set of data which describe the desired state of the system (e.g. source positions, observing frequencies, etc.), and this data is stored in a GLOBAL COMMON area which can be accessed by all of the above programs. Since the GLOBAL COMMON data tell the set of tracking programs what to do, the user interface to the tracking programs simply provides the means to adjust parameters in GLOBAL COMMON and to display their current values. These capabilities are provided by the OPCOM and SCREEN tasks, and in this chapter, we describe this user interface in detail.