| The term confusion noise refers to the uncertainty in the point
source flux determination due to the unknown backgrond. The sky background
(either made of the accumulated light of unresolved sources, or being intrinsically
diffuse) is not completely smooth. Due to its waves and rippels the actual background
level cannot be derermined absolutely correctly, which limits the achievable
photometric accuracy. The confusion noise is an absolute limit. Unlike
e.g. instrument noise, it cannot be improved by longer integration times, since it is
a signal itself -- the signal of the background.
The actual level of confusion noise depends on the main properites -- strength and
structure -- of the sky background. In the infrared -- due to both instrumental and
astrophysical reasons - the confusion noise is a major
limitation for deep survey, as well as for the photometric accuracy of single
source observations. In the infared the main astrophyical components of the confusion noise
are the cosmic infrared background, the Galactic cirrus emission and the thermal emission
of interplanetary dust and small bodies in the Solar System. In the recent years our work
focused mostly on the far-infrared part of the confusion noise and on its consequences for
specific space-born instruments, as demontrated by the papers listed below
(ISO, Spitzer, Herschel).
The main topics presented in this page are: |
 Main astrophysical components contributing to the far-infrared background and confusion noise for a space instrument (click on the image to enlarge) |
Sky confusion noise in the far-infrared:
Cirrus, galaxies and the cosmic far-infrared background;
Kiss, Cs.; Ábrahám, P., Klaas, U.; Juvela, M.; Lemke, D., 2001, A&A 379, 1161
[A&A at EDP Sciences]
[astro-ph/0110143]
We present the on-line material of the paper A&A 430, 343 (2005) below.
Please read the paper (several PS/PDF versions below) before using the FITS products.
The Herschel Confusion Noise Estimator (HCNE) is an application, which is part of
HSpot,
the observation designing enviroment for the
Herschel Space Observatory.
The HCNE is developped under the
scientific coordination of Konkoly Observatory, with the contribution of
ESA/ESTEC and the Herschel Science Center at IPAC.
HCNE is going to provide confusion noise estimates for
Herschel/PACS and SPIRE photometric bands,
for the measurement configuration specified by the observer.
Small-scale structure of the galactic cirrus emission;
Kiss, Cs.; Ábrahám, P., Klaas, U.; Lemke, D.; Héraudeau, Ph.; del Burgo, C.;
Herbstmeier, U., 2003, A&A 379, 1161
[A&A at EDP Sciences]
[astro-ph/0212094]
Determination of confusion noise for far-infrared measurements,
Kiss, Cs.; Klaas, U.; Lemke, D., 2005, A&A 430, 343
[A&A at EDP Sciences]
[astro-ph/0409336]
-- Table 1
Traceability matrix of ISOPHOT measurement configurations
--
Table 2 C0, C1 and
η coefficients for the C100 90um filter
--
Table 3 C0, C1 and
η coefficients for the C100 100um filter
--
Table 4 C0, C1 and
η coefficients for the C200 170um filter
--
Table 5 C0, C1 and
η coefficients for the C200 200um filter
--
Table 6 C0, C1 and
η coefficients for C100 90 and 100um and C200 170 and 200um minimaps
--
Table 7 C0, C1 and
η coefficients for P3 100um measurements
An asteroid model of the mid- and far-infrared sky;
Kiss, Cs.; Pál, A.; Müller, Th.; Ábrahám, P.,
2006, PADEU 17, 135
[PDF version]
