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Overview of in-flight sensitivity limits

Table 1 gives the detection limit of ISOPHOT. It is determined by the detector noise, by the photon noise from the source plus the expected background, flat-field uncertainties, as well as by the galaxy and cirrus confusion noise. We have added in this table values for the cirrus confusion and galaxy confusion limits for representative background values.


Table 1: Sensitivity limit ( tex2html_wrap_inline174 ) for typical filters compared to cirrus confusion (CC) and galaxy confusion (GC) limits per aperture/pixel for representative background levels. The noise values are given for S/N=10, 5 sigma in the case of CC and GC noise, 128 sec on-source integration time, and a source to background distance of 180'' (one background position) without any detector transients. Note that 5 sigma CC or CG noise peaks are rare, but nevertheless likely to occur in samples.  

Detector filter Aperture tex2html_wrap_inline190 tex2html_wrap_inline192 CC GC
[ tex2html_wrap_inline194 m] [''] [mJy] [MJy/sr] [mJy] [mJy]
P3 60 99 120 2 20 40
P3 100 180 240 10 2960 140
C100 60 1 pixel 180 2 30 20
C100 100 1 pixel 150 10 290 20
C200 160 1 pixel 200 10 1180 60
C200 160 1 pixel 920 7 690 100

Table 1 indicates that for C100 and C200 the cirrus confusion is an important factor in the determination of the limiting terms.


next up previous contents
Next: Observational limitations Up: Limitations Previous: Limitations

R.J. Laureijs, P. Abraham, U. Herbstmeier, U. Klaas, T. Muller, and the ISOPHOT Instrument Dedicated Team
Fri Aug 30 16:17:39 MET DST 1996