This mode is dedicated to spectrophotometry at a single position using the
PHT-S sub-instrument in either staring or chopped mode. Two detector
arrays are in simultaneous operation measuring the wavelength ranges
from approximately 2.5 to 
and 6 to 
,
respectively (for more details on the wavelength ranges see
Tab. 13). Depending on the source
spectrum (shape of continuum, strength of line features) and the sky background,
the best detector setting for both wavelength ranges may be very
different. The observer can therefore define the most interesting
wavelength range, either the short or the long wavelength channel or both.
The detector setting will be optimized for that range allowing for saturation
or degraded performance in the other range.
The entrance aperture for PHT-S observations is 24x24``.
Since this AOT does not contain an FCS calibration the following
alternatives can be used for photometric calibration: 1) a cross
calibration with the PHT-P1 detector (AOT PHT03) in the 
filter (for PHT-SS) and the 
filter (for PHT-SL); 2)
a PHT-S observation of a standard source located within 1.5 degrees of the
target. In the latter case a concatenated observation has to
be performed.
A raster at regularly spaced positions may be performed with this AOT. In this case, however, chopping is not possible. Note that the same detector setting is used at all raster positions. Therefore, the observer has to be aware of the flux variations over the area to be mapped when specifying the source flux properties.
This observing mode aims at the determination of the chemical composition of interplanetary and interstellar dust and the excitation mechanisms of the heating sources. The relatively low spectral resolution of PHT-S is matched to the typical widths of dust features. It is also the most effective spectroscopic instrument for detection of atomic or ionic emission of fainter sources because of the simultaneous measurement of the whole wavelength range.