IRAS Explanatory Supplement
XI. Known Processing Anomalies
I. Position Uncertainties
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As described in Section VII.C.1.b, the IRAS position uncertainties are significantly overestimated for brighter objects. An additional source of overestimation of the uncertainties for some objects was a processing error that added 3" in quadrature to the in-scan uncertainty for all sources with a cross-scan uniform uncertainty of 1". It had been intended to do this only for faint sources, about 40% of the catalog, but was inadvertently applied to sources of all flux levels meeting the uncertainty criterion, about 60% of the catalog.
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