The kmo_sky_mask recipe

kmo_sky_mask

Synopsis

Create a mask of spatial pixels that indicates which pixels can be considered as sky.

Description

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.

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

Constructor

cpl.Recipe("kmo_sky_mask")

Create an object for the recipe kmo_sky_mask.

import cpl
kmo_sky_mask = cpl.Recipe("kmo_sky_mask")

Parameters

kmo_sky_mask.param.range

Min & max wavelengths to use in sky pixel determination, e.g. [x1_start,x1_end] (microns). (str; default: ‘’) [default=”“].

kmo_sky_mask.param.fraction

Minimum fraction of spatial pixels to select as sky (value between 0 and 1). (float; default: 0.95) [default=0.95].

kmo_sky_mask.param.cpos_rej

The positive rejection threshold for kappa-sigma-clipping (sigma). (float; default: 3.0) [default=3.0].

kmo_sky_mask.param.cneg_rej

The negative rejection threshold for kappa-sigma-clipping (sigma). (float; default: 3.0) [default=3.0].

kmo_sky_mask.param.citer

The number of iterations for kappa-sigma-clipping. (int; default: 3) [default=3].

The following code snippet shows the default settings for the available parameters.

import cpl
kmo_sky_mask = cpl.Recipe("kmo_sky_mask")

kmo_sky_mask.param.range = ""
kmo_sky_mask.param.fraction = 0.95
kmo_sky_mask.param.cpos_rej = 3.0
kmo_sky_mask.param.cneg_rej = 3.0
kmo_sky_mask.param.citer = 3

You may also set or overwrite some or all parameters by the recipe parameter param, as shown in the following example:

import cpl
kmo_sky_mask = cpl.Recipe("kmo_sky_mask")
[...]
res = kmo_sky_mask( ..., param = {"range":"", "fraction":0.95})

See also

cpl.Recipe for more information about the recipe object.

Bug reports

Please report any problems to Alex Agudo Berbel. Alternatively, you may send a report to the ESO User Support Department.