Spitzer Documentation & Tools
MOPEX User's Guide

5.6.2        Mosaic Modules: Mosaic Settings

Command Line Equivalent: N/A

Default Output Directory: N/A

Depends On: Initial Setup

 

Important Notes: None

 

PURPOSE

To set the input parameters specific to the Mosaic pipeline.

 

INPUT

Pixel by Size: Check this to set the output pixel size in degrees. The default pixel size depends on the instrument and channel: see the templates for the default sizes.

 

Pixel Size X (deg): Set the X-size of the output pixels in degrees. The pixel size in the X-direction is quoted as a negative value to comply with convention. A positive value will generate an error message. 

Pixel Size Y (deg): Set the Y-size of the output pixels in degrees.

 

Pixel By Ratio: Check this to set the output pixel size by ratio of the input pixel to the output pixel, i.e. to make the output pixels half the size of the input pixels (over-sample the mosaic), set the values of Pixel Ratio X(Y) = 2. The ratio is taken after correction for geometric distortion.

 

Pixel Ratio X: Set the pixel ratio in the X-direction.

Pixel Ratio Y: Set the pixel ratio in the Y-direction.

 

Array-Location Dependent Photometric Correction Mosaic: This allows you to  set the defaults for the two parameters below, based on when the IRAC data were taken.

 

 

Array Correction Frame: The name of the Array Location Dependence Correction image (for IRAC only). This file is only required if you have included the modules Make Array Correction Files or Make Array Correction Mosaic (see those modules for more information). The default location for this file is the cal/ directory of your MOPEX installation, but you may need to download the correction files from the website.

 

PixArea Frame: The name of the Pixel Distortion Correction image (for IRAC only). This file is only required if you have included the modules Make Array Correction Files or Make Array Correction Mosaic (see those modules for more information). The default location for this file is the cal/ directory of your MOPEX installation, but you may need to download the correction files from the website.

 

Delete Array Correction Intermediate Files: Check this box to delete the intermediate files created by the Array Location Dependence Correction calculation. This is useful for saving disk space once you are satisfied with your reduction setup.

 

Moving Object Mosaic: This setting gives you the option to create a mosaic in the rest frame of a moving object (e.g. a comet or asteroid). The "stationary" frame is chosen with the value of this keyword, and all other images are shifted relative to the stationary frame. i.e. if Moving Object Mosaic = 5, MOPEX uses the 5th frame in the input stack as the base image, and shifts all other images to put the moving object at the same sky position. This functionality is limited to Spitzer data. See §5.4 for more information on creating Moving Object Mosaics.

 

Delete Intermediate Files: Check this to delete all of the intermediate files created by the Mosaic pipeline. This leaves only the input files and the files created by the final module. This is useful for saving disk space once you are satisfied with your reduction setup. Note that MOPEX will prompt you with a pop-up dialogueue box at the end of the flow, to be sure that you meant to select this irreversible option.

 

Use Refined Pointing: Check this to use the alternate FITS pointing keywords created by the offline pointing refinement script (pointing_refine.pl). Do not switch this on unless you have manually run pointing refinement outside of the normal BCD pipeline products. Most users will never use this option, as pointing refinement is not recommended for Spitzer data. If you believe that there is a problem with the pointing of your data with respect to e.g. the 2MASS catalog, please email the Spitzer Helpdesk for assistance.

 

Create Absolute Minimum Mosaic: This option sets the Mosaic CoAdder module to create an absolute minimum mosaic (mosaic.fits) and the corresponding uncertainty mosaic (mosaic_unc.fits) instead of the usual mosaic output. It will cause MOPEX to overwrite any identically named files in the output directory. The mosaic pixel value is set to the input pixel value with the smallest absolute value in the stack of the interpolated images. The corresponding mosaic uncertainty pixel is set to the pixel value in the interpolated uncertainty image corresponding to the interpolated image with the smallest absolute pixel value. This setting is useful for outlier rejection.

 

COMMAND LINE INPUT

The following parameters are set in the Global Parameters part of the namelist. Note that if both MOSAIC_PIXEL_SIZE_X(Y) and MOSAIC_PIXEL_RATIO_X(Y) are both set, the former takes precedence and will override the latter.

MOSAIC_PIXEL_SIZE_X = -0.00033889

MOSAIC_PIXEL_SIZE_Y = 0.00033889

MOSAIC_PIXEL_RATIO_X = 1

MOSAIC_PIXEL_RATIO_Y = 1

ARRAY_CORR_IMAGE = <mopex_dir>/cal/ch1_photcorr_rj.fits

ARRAY_PIXAREA_IMAGE = <mopex_dir>/cal/ch1relpixarea.fits

MOVING_OBJECT_MOSAIC = 5

delete_intermediate_files = 0

USE_REFINED_POINTING = 0

run_absolute_minimum_mosaic = 0

 

OUTPUT

None

 

DISCUSSION

Mosaic Settings sets up all of the input options that are specific to the Mosaic pipeline. Some of them may be repeated from the Overlap Settings, so you should be aware that you may need to match some settings (e.g. Pixel Ratio) between the pipelines.