subtract_bias

ndmapper.lib.gmos.spec.ifu.subtract_bias(*args, **kwargs)

Subtract overscan level & pixel-to-pixel variations in zero point. This also (as an artifact of using gfreduce) converts the units to electrons.

Parameters:

inputs : DataFileList or DataFile

Input images from which to subtract the bias & overscan levels and trim off the overscan region. Currently these must reside in the current working directory (which will normally be the case after running prepare). Each input image should already have an entry named ‘bias’ in its dictionary of associated calibration files (cals attribute); these bias images should already have their overscan levels subtracted and overscan columns removed.

out_names : str-like or list of str-like, optional

Names of output bias-subtracted files. If None (default), the names of the DataFile instances returned will be constructed from those of the input files, prefixed with ‘r’ as in the Gemini IRAF package.

ovs_function : str

Function to use for fitting the overscan region in IRAF (default ‘spline3’; may also be ‘chebyshev, ‘legendre’ or ‘spline1’).

ovs_order : int

Order of the overscan fitting function (default 1).

ovs_lsigma : float

Negative sigma rejection threshold for overscan fitting (default 2.0).

ovs_hsigma : float

Positive sigma rejection threshold for overscan fitting (default 2.0).

ovs_niter : int

Number of rejection iterations for overscan fitting (default 5).

interact : bool, None

Fit the overscan region interactively in IRAF? If None (default), interactivity is instead controlled by the package configuration dictionary (see below).

See “help gfreduce” in IRAF for more detailed information.

Returns:

outimages : DataFileList

The bias-subtracted images produced by gfreduce.