Configuration Parameters

A number of reduction parameters can be changed using entries in the configuration file.

If you installed the pipeline with pip, the configuration file will not be easy to find, since it will be stored with installed pip packages. If you need to modify the configuration, we advise that you download a copy of the config file, saving it to some easy to remember location, and using the -c option to point to that file.

If you installed the package via git, the master copy of the configuration file is in the installation directory, in kcwidrp/config/kcwi.cfg. This file can be modified in place or copied in another directory (the -c option of the main reduction script is used to specify the configuration file).

The configuration file contains a number of parameters connected to the structure of the files and to the specifications of the instrument, e.g. the number of continuum bars. There is usually no reason to modify these parameters, and they are not described here.

The remaining parameters are used to control the processing algorithms and are described here.

Processing parameters

output_directory = "redux"

This parameter specifies the output directory for the data products. If this directory is missing, it will be created automatically.

bias_min_nframes = 7
flat_min_nframes = 6
dome_min_nframes = 3
twiflat_min_nframes = 1
dark_min_nframes = 3

These parameters control the minimum number of bias, internal/dome/twilight flats and darks that the DRP expects before producing a master calibration. The values shown here are synchronized with the calibration scripts that we use in the afternoon.

clobber = False

This parameters controls the behaviour of the DRP if one of the data product has already been generated: set clobber = True to overwrite existing products.

skipscat = False    # Skip subtracting scattered light?

This parameter disables the subtraction of scatteres light if set to True. In some case the subtraction of scattered light can produce unexpected results.

default_arc_lamp = 'ThAr'

KCWI has two calibration lamps, Thorium/Argon (ThAr) and Iron/Argon (FeAr). This parameter specifies which of the two lamps should be used by the DRP. The default is to use the ThAr lamp.

Plotting parameters

plot_pause = 1
saveintims = False
inter = 1
plot_width=1000
plot_height=600

# BOKEH SERVER
enable_bokeh = False
plot_level = 0

These parameters control the plotting features of the DRP. Plotting is performed using a combination of a Bokeh server running in the background and a browser front end.

To activate the plotting features, set enable_bokeh = True. When the DRP starts, it will check if there is an instance of the Bokeh server running or start one. A browser window will be opened automatically when needed.

The plot_level parameter controls the level of interactivity. Setting it 0 will disable interactive fetures: the DRP will produce plots when needed but it will not interact with the user. A higher level will increase both the verbosity and the interactivity of the plots. The highest level is 3 (CHECK). At this level, the user will be provided with a plot of every arc line, for example, with a graphic representation of the fitting used to determine the central position.

For general use, it is advisable to leave the plot level to 1.

The plot_pause parameter controls how long the DRP will pause between automatically generated plots (in seconds). Finally, the saventims parameter controls the generation of JPG diagnostics plots saved in the current directory.

The size of the plotting window can be specified using plot_width and plot_height.

Cosmic rays rejection parameters

CRR_MINEXPTIME = 60.0
CRR_PSSL = 0.0
CRR_GAIN = 1.0
CRR_READNOISE = 3.2
CRR_SIGCLIP = 4.5
CRR_SIGFRAC = 0.3
CRR_OBJLIM = 4.0
CRR_PSFFWHM = 2.5
CRR_FSMODE = "median"
CRR_PSFMODEL = "gauss"
CRR_SATLEVEL = 60000.0
CRR_VERBOSE = False
CRR_SEPMED = False
CRR_CLEANTYPE = "meanmask"
CRR_NITER = 4

These parameters are used to control the CRR algorithms. See the documentation in astroscrappy for details (PROVIDE LINK)

Wavelength correction parameters:

The radial_velocity_correction parameter controls what reference frame to use for radial velocity corrections. The options are heliocentric, barycentric, or none

The air_to_vacuum parameter controls if the pipeline should convert to vacuum wavelengths from air wavelengths.