for the Observer's choice of the channel, PFOV, filter, 
,
and (S/N), compute:
S, K and s as for AOT 1 single pointing.(section
).
= function of S and 
(see section
).
= function of S and (see section
).
= 
. Note:
only the source flux is affected by the flat-field.
is neglected in first approximation.
Then solve for :
In any case, must be larger than 4 for deglitching.