The basic observation is initiated by the command observe. The system will print on the screen, one at a time, those parameters selected by eask, and the current value [_], prompting for entry of a new value or <cr>, which will enter the current value. The command go will begin an observation, but will use the current values for the parameters (except the picture index, which will be automatically incremented). The command movie will begin a loop consisting of an observation (using the current parameters!) and a display; this may be terminated with end at any time. The observation in progress will be completed and displayed. The picture index parameter is incremented at the nd of a movie, so it generates a large number of images on disk, the last movie image is a valid image which may be examined within IRAF. To help with house keeping it is useful to change the filename parameter before starting a movie to some thing like ``junk''.
Like the old ``obsno'' parameter, the picture index parameter `nextpic' is both powerful and dangerous. One may modify it to larger values or smaller values (to write over bad data), but it should not be changed unless the observer knows exactly what it should be; one can write over good data as well as bad. Keep good logs! Note that changing the filname prefix does not change the value of `nextpic' so you must reset yourself as needed.
The ask command will cycle through the selected parameters, prompting for changes, just as with obs, but will NOT begin an observation. This command is useful for checking parameters, and is essential before executing movie, which will use the parameters for the previous observation, even if it was 600s in length.