Input data from the individual subarrays are combined to produce a single mosaic for each time step. Sky removal and extinction correction take place on these images before they are combined into a single Frame image.

The Frame image is calibrated and displayed, before being combined with the Group image in a running average. The noise properties of the new Group image are calculated and logged, and the image searched for sources.

• This primitive can not handle time series data.

• The current noise level is stored in log.noise, the positions and fluxes of any sources are stored in log.flux.

The Frame image is displayed in Gaia window 1. The Group image is displayed in Gaia window 2; its variance is displayed in window 3.