Optimizing ISOCAM data processing using spatial redundancy
M. A. Miville-Deschênes, F. Boulanger, A. Abergel, J. P. Bernard;
AaAS, 2000, 146, 519
ABSTRACT:Several instrumental effects of the Long Wavelength channel of ISOCAM, the camera on board the Infrared Space Observatory, degrade the
processed images.
We present new data-processing techniques that correct
these defects, taking advantage of the fact that a position in the sky has been
observed by several pixels at different times.
We use this redundant
information (1) to correct the long-term variation of the detector response, (2) to
correct memory effects after glitches and point sources, and (3) to refine the
deglitching process.
As an example we have applied our processing to the gamma-ray
burst observation GRB 970402.
Our new data-processing techniques allow
the detection of faint extended emission with contrast smaller than 1% of
the zodiacal background.
The data reduction corrects instrumental
effects to the point where the noise in the final map is dominated by the readout
and the photon noises.
All raster ISOCAM observations can benefit from
the data processing described here.
This includes mapping of solar
system extended objects (comet dust trails), nearby clouds and star forming
regions, images from diffuse emission in the Galactic plane and external
galaxies.
These techniques could also be applied to other raster type observations
(e.g.
ISOPHOT).
Based on observations with ISO, an ESA project with instruments funded
by ESA Member States (especially the PI countries: France, Germany, The
Netherlands and the UK) and with the participation of ISAS and NASA.
KEYWORDS: techniques: image processing, infrared: general, instrumentation: detectors
CODE: miville-deschenes2000a