Users are recommended to use SOTE or to look at figure 6.5 to get an approximate idea as to how long an observation will require.
Remember that merging will occur for FP Observations and SW grating
observations in the region 2.38-7 
m where observations use the same
aperture. Grating observations through apertures 1 and 2, times for which can
be calculated from the data given describing AOT 6, should be planned so as
not to require extra time.
The minimum observation time for an AOT 7 is approximately 300 seconds OTT. To this time has to be added the 180 seconds for slewing to the target, or five minutes if it is a Solar-System Object. For Solar-System Objects, one AOT can only observe through one aperture.