Basic Reduction Assessments

Analysis class: ReductionAssessment

Reference root: see common_path; $MANGA_SPECTRO_ANALYSIS/$MANGADRP_VER/$MANGADAP_VER/common/[PLATE]/[IFUDESIGN] for MaNGA

Reference file: see default_paths; manga-[PLATE]-[IFUDESIGN]-[RDXQA].fits.gz for MaNGA

Optional Parameters: see Analysis Plans. The table below lists the parameters defined by ReductionAssessmentDef

Key	Type	Options	Default	Description
key	str		SNRG	Keyword to distinguish the assessment method.
waverange	ndarray, list			A two-element vector with the starting and ending wavelength within which to calculate the signal-to-noise. Mutually exclusive with response_func_file
response_func_file	str		gunn_2001_g_response.db	The name of a file that defines a response function to use for the S/N calculation. Must be a local file or distributed with the DAP source code. Expected to have two columns, with the wavelength and response efficiency. Mutually exclusive with waverange.
in_vacuum	bool		True	Boolean indicating that the wavelengths provided either using waverange or response_func_file are in vacuum (not air).
covariance	bool		True	Provide the fiducial spatial covariance. If this is False, no spatial covariance will be available for calculations that use the results of the reduction assessments. If True and a covariance matrix is available directly from the datacube, it will be used. If True and the datacube does not already provide a computed covariance matrix, one is calculated using covariance_matrix() method. WARNING: If either of these fail, the DAP will issue a warning and continue assuming no spatial covariance.
minimum_frac	int, float		0.8	Minimum fraction of unmasked pixels in a spectrum required for inclusion in the spatial covariance calculation. Note this should match the value used for the spatial-binning module.
overwrite	bool		False	If the output file already exists, redo all the calculations and overwrite it.

Important class dependencies:

• DataCube: Base class that provides the datacube to be assessed.

Algorithm:

• Ignore any pixels that are either masked by the boolean mask or flagged with the flags returned by do_not_use_flags().

• Compute sky coordinates of each spaxel using mean_sky_coordinates(). (SPX_SKYCOO in MAPS file)

• Use input ellipticity and position angle parameters to compute semi-major axis radii using SemiMajorAxisCoo (SPX_ELLCOO in MAPS file)

• Determine the fraction of unmasked wavelength channels for each spaxel

• If config specifies covariance calculation, compute the covariance using the LOGRSS file at:

  • the center of the wavelength range if wavelength limits specified or,

  • the broad-band weighted center of the response function

• Compute the (band-weighted) mean signal in each spaxel (SPX_MFLUX in MAPS file), (band-weighted) mean variance in each spaxel (SPX_MFLUX_IVAR in MAPS file), and the (band-weighted) mean S/N in each spaxel (SPX_SNR in MAPS file), using flux_stats().