ISOCAM Interactive Analysis User's Manual Version 5.0 - ISO - ESA

266 CHAPTER 20. ADVANCED DATA CALIBRATION
20.16 Faint source data reduction with PRETI
Several methods for ISOCAM faint source data reduction exist:
triple-beam-method (Désert, et al., 1999)
Lari method (Lari, et al., 2001)
This method is coded in IDL, and available as add-on package to CIA. For more informatation,
please contact Carlo Lari (lari@ira.bo.cnr.it)
Metcalfe method (Blommaert, et al., 2002)
This method is coded in IDL, and completely based on CIA routines. For more information,
please contact the ISO helpdesk (helpdesk@iso.vilspa.esa.es)
PRETI method (Starck, et al., 1999)
This method is based on the multiresolution package MR/2. The corresponding C++
executable for Sun/Solaris is provide is with CIA, together with its IDL interface reduce
faint source, which performs the following data-reduction steps:
1. Slice the CISP file and create a raster pds
2. Dark correction
3. Calling the PRETI C++ executable which corrects glitches and performs a median
flat-fielding
4. Optional: Transient correction
5. Conversion to milli-Jansky
6. Averaging the CUBE into EXPOSURES
7. Projection of the IMAGETTES into the MOSAIC
Calling syntax is:
CIA> reduce_faint_source, ’cisp_file.fits’, raster
20.17 Error handling in CIA
In this section we discuss the error calculated by CIA during the calibration and data reduction
stages. We use the standard definitions:
Mean = ¯x = 1 N
N−1
∑
j=0
x j (20.2)
Variance = σ 2 = 1 N−1
∑
(x j − ¯x) 2 (20.3)
N − 1
j=0
Standard Deviation = σ = √ Variance (20.4)
σ
Standard Error = √
N − 1
(20.5)