MOPEX Online Manual

Modules: Fix Coverage

PURPOSE

After all outlier pixels have been identified, there is the option to suppress usage of pixels which have very small coverage (number of repeated observations at the same point of sky). Pixels whose usage is supressed have their coverage set to 0 in new coverage maps.

PARAMETER BLOCK

There is no parameter block for this module. There are two input parameters for this module (see below), but the default values cannot be changed on the command-line, only in the GUI.

Min_Single_Coverage = 0.95,
Min_Block_Coverage = 0.83,

INPUTS

Min_Single_Coverage: (float) The minimum coverage for an individual pixel. The default value is 0.95.

Min_Block_Coverage: (float) The minimum average coverage in the block of 9 pixels centered on a given pixel for it to be retained. The default value is 0.83

OUTPUTS

Fix Coverage Images (fixed_covg_*.fits): The stack of corrected coverage maps.

DISCUSSION

Two thresholds are used for each coverage map pixel, one - Min_Single_Coverage - for the pixel value alone and the other one - Min_Block_Coverage - for the sum of the values of the block of 9 pixels centered on the pixel in question (see Figure 1). The following logic is used:

IF C₅ < Min_Single_Coverage THEN C₅ = 0;

IF (C₁ + C₂ + C₃ + C₄ + C₅ + C₆ + C₇ + C₈ + C₉) < 9 * Min_Block_Coverage THEN C₅ = 0.

Figure 1: Coverage for the central pixel (C₅) is fixed based on the two thresholds, one for C₅ and the second one for the sum of all nine C_i's.