rectify_wavelength

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

Resample (“transform”) fibre spectra onto a pixel array with a linear wavelength increment.

This step currently depends on a version of gftransform that has been patched with respect to the public version 1.13.1, to accept ”.fits” in the filenames passed to its wavtraname parameter. This change is available in the “ifudrgmos” version of the GMOS package (r145+) and is likely to be included in the public Gemini IRAF package in 2017.

Parameters:

inputs : DataFileList or DataFile

Input images, containing extracted fibre spectra, to be interpolated and resampled to linear World co-ordinates along the wavelength axis. Each input must already have an associated entry named ‘arc’ in its cals dictionary (whose name is used by gftransform, in the current

implementation, to find the corresponding IRAF database files).

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

Names of output images with a constant increment in wavelength per pixel. If None (default), the names of the DataFile instances returned will be constructed from those of the input files, prefixed with ‘t’ as in the Gemini IRAF package.

start_wl, end_wl, delta_wl : float, optional

Starting & ending wavelengths (at the centre of the first/last column) and wavelength increment per pixel to use for the output grid, in the same units as the database (? Usually Angstroms). By default, the output spans the same average wavelength range as the input, with the same number of pixels. Any combination of these parameters and npix can be overridden (precedence if all four specified TBC), leaving the remainder to be determined based on the input.

npix : int, optional

Length in pixels of the wavelength axis of the output image(s), by default the same as in the input (used in conjuction with start_wl, end_wl & delta_wl to constrain the wavelength increment & range).

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

Returns:

outimages : DataFileList

The resampled spectra produced by gftransform, with a linear wavelength increment.