This module performs a projection of input images onto a 2D plane defined by the FIF table, and an interpolation (see §8.4) of the input pixel values to the output array of pixels of the user-defined pixel size. It corrects for the optical distortion in the input images, using the WCS distortion parameters in the input FITS headers. The process is intended to accept images measuring surface brightness (MJy/sr or microJy/arcsec2) and to yield images in the same units, but it is not restricted to this. If the input FITS header does not contain an allowed string specifying units of MJy/sr or microJy/arcsec2, then it will assume the input units are counts.
INPUT
INTERP METHOD: There are four possible interpolation methods. These are discussed in §.5.6.8. Since high spatial frequency information is not critical for simple background-matching, the default templates for Overlap use a coarse Grid method for speed.
Mosaic Interpolate output subdirectory: The subdirectory of <output_dir> that you wish to use for the output files. Default is Interp-overlap.
Mask bright object: Check this box to tell MOPEX to implement Bright Object Masking. This masks bright objects in the BCDs, and so should provide a more accurate background-matching result where there are bright objects in the field of view.
COMMAND LINE INPUT
&MOSAICINTIN
INTERP_METHOD = 3,
FINERES = 0,
DRIZ_FAC = 1,
GRID_RATIO = 4,
ALPHA = -0.5,
&END
In Global Parameters:
mask_bright = 1
INTERP_DIR = Interp-overlap
OUTPUT
Mosaic FIF Table(mosaic_fif.tbl): The FIF table describing the final mosaic, taking into account the user-selected pixel size. Note: This file is saved in the top level Output directory.
Geometry Output Table(interp_ImageList.txt.tbl): The interpolated images' offsets in x- and y-direction relative to the FIF and their sizes are specified in this file.
Interp Stack(interp_*fits): The output images, interpolated, distortion-corrected, and projected onto the output FIF. A list is also made.
Coverage Stack (interp_*covg.fits): The corresponding coverage maps for each output image, taking into account the bad pixels in the input. A list is also made.
DISCUSSION
When choosing your interpolation scheme, bear in mind that each frame is overlap-corrected by a single value for the entire frame. If speed or memory are a factor when running MOPEX on your machine, then you may want to consider a simple interpolation scheme here (e.g. Grid), and reserve the more complicated interpolation for the Mosaic script. The Grid option is the default in the Overlap Pipeline for this reason.
