Currently we recommend four different observing strategies to the observer as 
outlined in 'Detection limits and observing strategy for very faint point 
sources' (SAI/96-188/Doc, Laureijs et al). From the available observations we 
can deduce the detection limits in the 90 micron band, and concerning signal 
derivation we see a preference for the telescope nodding technique. From our 
recent C200 measurements (see "Report on ISOPHOT C160 observations of HR 6132"
by Abraham et al. from 14/10/96) we have found, that in case of significant 
cirrus contamination two reference positions may not be sufficient in order 
to derive the true background level and the amplitude of the background 
fluctuations. The C100 and C200 detectors behave different w.r.t. noise and 
signal transients which are considered to be essential criteria for selection
of the right mapping mode.


Date:	20/11/96
U. Klaas, R.J. Laureijs

.OTT 10362
.TDT 11702