Spatial masking
Purpose
nGIST is currently equipped with one routine to mask spatial regions in the IFU cube. This routine is included in the source code and can readily be used by setting the configuration parameter SPATIAL_MASKING: METHOD
to default. This routine performs three tasks:
-
It masks defunct spaxels, i.e. spaxels with negative mean values or those containing np.nan’s.
-
It applies a signal-to-noise threshold. In particular, it masks all spaxels below the isophote level which has a mean signal-to-noise ratio of
SPATIAL_MASKING: MIN_SNR
. -
It applies a manually defined mask. In particular, it reads a fits-file which path is given by the parameter
SPATIAL_MASKING:MASK
(path relative toGENERAL:INPUT
; set to False to turn this option off). The file is expected to have the same spatial dimensions as the input IFU cube. Unmasked spaxels should have the value 0, while masked spaxels should have the value 1.
Config file input
SPATIAL_MASKING :
METHOD : 'default' #'default' # Name of the routine in spatialMasking/ (without .py) to perform the tasks. Set 'False' to turn off module. Set 'default' to use the standard GIST implementation.
MIN_SNR : 1.5 # Spaxels below the isophote level which has this mean signal-to-noise level are masked.
MASK : 'NGC0000_mask.fits' # File containing a spatial mask (Set 'False' to not include a file).
Output
Files
-
*_mask.fits
: Contains information on the spatial masking.-
Columns:
MASK
Combination of all masks |MASK_DEFUNCT
Mask based on defunct spaxels |MASK_SNR
Mask based on signal-to-noise criterion |MASK_FILE
Mask based on file -
Rows: One line per spaxel.
-
Function returns
The module should end with return(None)
. If an uncaught exception occurs in the module, all following modules will be skipped for this galaxy. If you intend to manually skip all subsequent modules, simply raise an exception.