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<strong>MOPEX</strong> User’s <strong>Guide</strong><br />
Choosing the right kind of outlier rejection (§8.2) also requires some care. Rejection schemes<br />
utilize either temporal information (rejecting sources that do not appear at the same coordinates in<br />
every frame) or spatial information (rejecting outliers based on their shape or size), or both. In the<br />
case of good coverage per pixel (about 10 or more BCDs per pixel on the sky), multiframe<br />
temporal outlier re jection (§8.2.2) can be a good choice. To add multiframe temporal outlier<br />
rejection, use the Mosaic Outlier module (§5.6.14). When using multiframe temporal outlier<br />
rejection, be careful when setting the rejection thresholds. A three-sigma rejection is often too<br />
low if the coverage is very high (50 or more). If only shallow coverage is available, then either<br />
the box outlier rejection (§8.2.4) (include module Mosaic Box Outlier, §5.6.15) or dual spatialtemporal<br />
outlier rejection (§8.2.3) are preferred. Dual outlier rejection requires the following<br />
modules:<br />
• MedFilter (§5.6.6)<br />
• Detect (§5.6.9)<br />
• Mosaic Projection (§5.6.10)<br />
• Mosaic Dual Outlier (§5.6.12)<br />
• Level (§5.6.13)<br />
Multiple outlier rejection methods can be employed, and all can be set to contribute to the RMask<br />
by setting the RMask Fatal Bit Pattern (see §8.11: Fatal Mask Bit Patterns). The Mosaic RMask<br />
module (§5.6.16) can also use the dual outlier rejection results as a check on the temporal outlier<br />
identifications (the Refine Outlier option). This combination can be useful to prevent the false<br />
identification of temporal outliers inside bright sources.<br />
The Mosaic pipeline can produce a number of final outputs. The most basic output files that you<br />
will need are the mosaic and its coverage map and uncertainty file (mosaic.fits, mosaic_cov.fits,<br />
and mosaic_unc.fits). For more options, see §5.5 “Mosaic Pipeline Stages.”<br />
2.5.3 APEX Single Frame (apex_1frame.pl)<br />
Source extraction can be performed on the mosaic image using APEX Single Frame mode<br />
(Chapter 6). This takes a single image (together with an optional coverage map and optional<br />
uncertainty file) as input. It can be used independently or as a follow-on to the Mosaic pipeline.<br />
A typical APEX Single Frame task might include background subtraction, noise estimation, nonlinear<br />
filtering, point source detection, point source fitting and flux estimation, and aperture<br />
photometry. These are carried out by the following modules:<br />
• Detect MedFilter (§6.5.8)<br />
• Point Source Probability (§6.5.9)<br />
Overview of <strong>MOPEX</strong> 15<br />
Which Modules Should I Choose?
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