ISSA Explanatory Supplement
IV. ANALYSIS RESULTS
A. Analysis Overview
IV. ANALYSIS RESULTS
A. Analysis Overview
Analysis of the IRAS Sky Survey Atlas was designed to verify the accuracy and analyze the quality of the ISSA images. The analysis is mainly confined to the high-ecliptic-latitude sky, released in 1991. The analysis concentrated on the position accuracy, photometric consistency, spatial resolution and noise of the Atlas. The results reported here are applicable to the entire ISSA data set, which covers the |
| > 20° sky.
The remaining set of images covering
the || < 20° sky is of
reduced quality and considered a separate product,
ISSA Reject Set. The reduction in quality is due to
residual zodiacal emission at the ecliptic plane and
the zodiacal bands. A separate
analysis is presented for these images, §IV.F.
The analysis results show that the ISSA
images are accurate to within the limitations of the IRAS data.
ISSA data are positioned accurately to better than 0.1 pixel.
The spatial resolution of ISSA
is 4.5' to 5'. Measurement of ISSA
point sources show that the data are
photometrically consistent with the IRAS Point Source Catalog
to within 10%. This uncertainty is due to the positioning of
a point source within the convolution filter that was used
to resample the full resolution IRAS data to
2' samples (Appendix B).
Relative surface brightness photometry over large
spatial scales is possible. The effects of detector-to-detector
offsets and zodiacal emission shifts have been reduced so that the
noise level in the ISSA
images in the high-ecliptic latitude sky is approximately that expected
from the noise in individual IRAS detectors.