Spectral Extraction
Extracting a 1D spectrum from the JWST IFU cube with CRETA
(Enabled but not supported in the current v1.0.0 of CAFE
)
The user can employ CRETA
to extract a continuous or discontinuous spectrum from one, some, or all data cubes that the user has copied and made available in the input_data/ directory. Currently CRETA
supports the extraction of individual spectra; that is, extractions along a single line-of-sight, or position in the sky. CRETA
will extract the spectrum based on a set of parameters provided by the user in a parameter file. Inside it, the user can specify:
cubes
: The cubes to be extracted (currently, only MIRI/MRS; the names provided here need to match or be a sub-string of the cube file names)
user_r_ap
: The radius of the circular aperture used for the extraction
user_ra
,user_dec
: RA and Dec coordinates of the source
point_source
: The method of extractions (point source: cone extraction, with radius increasing linearly with wavelength; extended source: cylinder extraction, with constant radius)
lambda_ap
: Wavelength reference for the definition of aperture radius (if point source extractions; ignored otherwise)
aperture_correction
: Whether to perform aperture correction based on PSF cubes
centering
: Whether to perform a centroid centering on the user provided coordinates
lambda_cent
: Wavelength at which the centering will be performed (ignored otherwise)
background_sub
: Whether to perform an annulus-based background subtraction prior to the aperture photometry
r_ann_in
: Inner radius of the background annulus (ignored otherwise)
ann_width
: Width of the background annulus (ignored otherwise)
Options for directory setup (specified in the command execution only):
data_path
(default: CRETA/data/)
PSFs_path
(default: CRETA/PSFs/)
output_path
(default: CRETA/extractions/)
output_filebase_name
(default: ‘last_result’)
parfile_path
(default: CRETA/param_files/)
parfile_name
(default: ‘single_params.txt’)
CRETA
will return a ‘_cube.fits’ file containing the extracted spectrum, which can be fed directly to CAFE
for fitting.
The specific steps to achieve this will be included in future releases in a jupyter notebook in the notebooks/ folder in the GitHub repository.