The nature of the PHT-S dynamic spectral response calibration (Section5.2.6) implies the following restrictions for measurements executed with AOT P40 in staring mode:
Caveat: The transient behaviour of the PHT-S detectors is temperature
dependent. The calibration was established for a certain temperature range
of the detectors. Since PHT-S was not actively temperature controlled,
the detector temperature can occur outside the calibrated range (2.7K
3.1K). In this case, a different transient behaviour of
the signals can be observed, leading to absolute and relative accuracies
which are worse than quoted. A warning message is included in the
PSSS and/or PSLS product headers.
Caveat: For certain wavelength ranges, fluxes of some targets can be outside the range covered by standard stars. For these targets a worsening is possible of the accuracy in the relative spectral shape. A warning message is included in the PSSS and/or PSLS product headers.
The scientific validation of the PHT-S observations led to the following two general caveats:
Caveat: The Zodiacal Light level
(see Section4.9.3) is below the
sensitivity limit of PHT-SS where the Zodiacal Light intensity is less
than 1MJysr
for 2.5 to 4.9
m.
Caveat: Quoted absolute accuracies are only valid for the Zodiacal
Light level in the PHT-SL range (Zodiacal Light intensity 
5 
20MJysr for 5.8 to 11.6m), if the
exposure time is 
1024 seconds.