MOPEX User's Guide - IRSA

MOPEX User’s Guide
Med Filter output subdirectory: The subdirectory of that you wish to use for
the output files. Default is Medfilter-mosaic.
COMMAND LINE INPUT
&MEDFILTER
Window_X = 45,
Window_Y = 45,
N_Outliers_Per_Window = 50,
Sbkg_Filt_Size_for_Med = 1,
Use_Sbkg_for_Med = 1,
&END
In Global Parameters:
MEDFILTER_DIR = Medfilter-mosaic
OUTPUT
Generated Fits Files (*_minback.fits): The background subtracted, individual images. A list
of the generated images is also written out.
DISCUSSION
This module is required in order to do single-frame (Detect Radhit) or dual (spatia l &
temporal) outlier rejection (see §8.2 Outlier Detection). The background subtraction is only
for the purpose of outlier rejection, and the background-subtracted images are not used for
later mosaicking.
With the default Median option, the program computes a background value using the median
of a running rectangular window of Window X by Window Y pixels, after omitting the
Outliers / Window highest pixels. This is done for each pixel so can be very slow.
If Use SExtractor background estimation is set, the module switches to the Sbkg background
estimation based on that of SExtractor (Bertin and Arnouts, AASupp 117, 393, 1996). The
image is divided into Panels with size given by Window X, Y. In each Panel, iterative clipping
is used to find a single estimate of the background in the Panel. You can optionally median
filter the Panel background values, e.g. to avoid ones where bright objects skewed the
background estimate. The median filter size is given by SExtractor background filter size. It
Mosaicking (mosaic.pl) 62
Mosaic Modules