kmo_sky_mask(7)

Usage

esorex kmo_sky_mask [OPTIONS] FILE.sof

Overview

This recipes calculates masks of the skies surrounding the objects in the diff- erent IFUs of a reconstructed F3I frame. In the resulting mask pixels belonging to objects have value 1 and sky pixels have value 0.

The noise and the background level of the input data cube are estimated using the mode calculated in kmo_stats. If the results aren´t satisfactory, try chan- ging --cpos_rej and --cneg_rej. Then pixels are flagged in the data cube which have a value less than the mode plus twice the noise (val < mode + 2*sigma).

For each spatial pixel the fraction of flagged pixels in its spectral channel is determined.

Spatial pixels are selected where the fraction of flagged spectral pixels is greater than 0.95 (corresponding to the 2*sigma above).

The input cube can contain noise extensions, but they will be ignored. The out- put doesn’t contain noise extensions.

Basic parameters

--fraction The fraction of pixels that have to be greater than the threshold can be defi- ned with this parameter (value must be between 0 and 1).

--range If required, a limited wavelength range can be defined (e.g. "1.8,2.1").

Advanced parameters

--cpos_rej --cneg_rej --citer An iterative sigma clipping is applied in order to calculate the mode (using kmo_stats). For each position all pixels in the spectrum are examined. If they deviate significantly, they will be rejected according to the conditions:
val > mean + stdev * cpos_rej
and
val < mean - stdev * cneg_rej In the first iteration median and percentile level are used.

Input files:

DO KMOS
category Type Explanation Required #Frames
-------- ----- ----------- -------- -------
<none or any> F3I The datacube frame Y 1

Output files:

DO KMOS
category Type Explanation
-------- ----- -----------
SKY_MASK F2I The mask frame

Options

--range <str>: Min & max wavelengths to use in sky pixel determination, e.g. [x1_start,x1_end] (microns). (str; default: ´´). The full name of this option for the EsoRex configuration file is kmos.kmo_sky_mask.range [default = ].

--fraction <float>: Minimum fraction of spatial pixels to select as sky (value between 0 and 1). (float; default: 0.95). The full name of this option for the EsoRex configuration file is kmos.kmo_sky_mask.fraction [default = 0.95].

--cpos_rej <float>: The positive rejection threshold for kappa-sigma-clipping (sigma). (float; default: 3.0). The full name of this option for the EsoRex configuration file is kmos.kmo_sky_mask.cpos_rej [default = 3.0].

--cneg_rej <float>: The negative rejection threshold for kappa-sigma-clipping (sigma). (float; default: 3.0). The full name of this option for the EsoRex configuration file is kmos.kmo_sky_mask.cneg_rej [default = 3.0].

--citer <int>: The number of iterations for kappa-sigma-clipping. (int; default: 3). The full name of this option for the EsoRex configuration file is kmos.kmo_sky_mask.citer [default = 3].

Note that it is possible to create a configuration file containing these options, along with suitable default values. Please refer to the details provided by the 'esorex --help' command.