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Read data

Purpose

Read the input data, for instance the IFU cube, and return the relevant information in a dictionary. Such a read-in routine has to perform the following tasks:

  • Read spectra and error spectra

  • Get the wavelength information

  • Get the spatial coordinates

  • Shift the spectra to restframe, according the configuration parameter GENERAL|REDSHIFT (Note that this is required for user-defined read-in routines, in order to work consistently with the subsequent modules).

  • Shorten the wavelength range of the spectra

  • Compute a signal-to-noise ratio for each spaxel

  • Determine the velscale of the spectra

Currently, nGIST has been tested only with the following read in routine(s): - MUSE_WFM The widefiels mode of the MUSE spectrograph without adaptive optics.

Config file input

READ_DATA :
 METHOD : 'MUSE_WFM' # Name of the routine in readData/ (without .py) to be used to read-in the input data.
 DEBUG : FALSE # Switch to activate debug mode [True/False]: Pipeline runs on one, central line of pixels. Keep in mind to clean output directory after running in DEBUG mode!
 ORIGIN : 222,223 #217,218 # Origin of the coordinate system in pixel coordinates: x,y (Indexing starts at 0).
 LMIN_TOT : 4800 # Spectra are shortened to the rest-frame wavelength range defined by LMIN_TOT and LMAX_TOT. Note that this wavelength range should be longer than all other wavelength ranges supplied to the modules [in Angst.]
 LMAX_TOT : 7000
 LMIN_SNR : 4800 # Rest-frame wavelength range used for the signal-to-noise calculation [in Angst.]
 LMAX_SNR : 7000
 EBmV : 0.104575 # [mag] Galactic foreground dust reddening correction for the RA, DEC of the target. Or set to null for no redenning correction.

Output

Files

None

Function returns

  • x x-coordinate for each spaxel [array, size=(nspaxel,)]

  • y y-coordinate for each spaxel [array, size=(nspaxel,)]

  • wave Wavelength array [array, size=(nspecs,)]

  • spec Spectra [array, size=(nspecs,nspaxel)]

  • error Error spectra [array, size=(nspecs,nspaxel)]

  • snr Signal-to-noise ratio for each spaxel [array, size=(nspaxel,)]

  • signal Signal in each spaxel [array, size=(nspaxel,)]

  • noise Noise in each spaxel [array, size=(nspaxel,)]

  • velscale Spectral pixelsize in velocity space [float]

  • pixelsize Spatial pixelsize of the instrument [float]

(nspaxel denotes the total number of spatial pixels; nspecs denotes the total number of spectral pixels)