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Post-Solution Pathology Tests

After a continuous Chebyshev solution is computed for a particular Pass 1 swath, a series of data pathology checks are performed on the solution (see Data Pathology Assessments). These tests are performed only on images of point and extended sources containing continuum flux. If the solution fails any of the pathology checks, an appropriate condition is relaxed (e.g. the PSF is not used to calculate the true interorder background, or the degree of the Chebyshev fit is decreased by one). The solution is then recalculated iteratively. Since even adjacent Pass 1 swaths sometimes can pass different pathology tests, their solutions can occasionally be different. This is a subtle but often important source of error in the final background solution. The results of these differing solutions are manifested as "spike structure" in Figure 4, as described below.

Last updated: 29 July 1997