Step Arguments

The master background subtraction step uses the following optional arguments.

--median_kernel

Optional user-supplied kernel size for a moving-median boxcar filter to filter outliers in the master background spectrum. The kernel size must be an odd integer. Even integers will be rounded down to the nearest odd integer. Defaults to 1 (which applies no median filtering).

--user_background

The file name of a user-supplied 1-D master background spectrum. Must be in the form of a standard x1d product containing a single ‘EXTRACT1D’ extension. When a user background spectrum is supplied, it is used for the subtraction instead of a computed master background, and the name of the user-supplied file is recorded in the MSTRBKGD keyword in the output product(s). Defaults to None.

--save_background

A boolean indicating whether the computed 1-D master background spectrum should be saved to a file. The file name uses a product type suffix of “masterbg”. For the master_background_mos step, multiple files will be produced including the 1-D master background spectrum (saved with the suffix “masterbg1d”), the expanded 2-D background spectra for each MOS slitlet (with the suffix “masterbg2d”), and the 1-D background spectra that were combined into the master background spectrum (with the suffix “bkgx1d”). If a user-supplied background is specified, this argument is ignored. Defaults to False.

--force_subtract

A boolean indicating whether or not to override the step’s built-in logic for determining if the step should be applied. By default, the step will be skipped if the calwebb_spec2 background step has already been applied. If --force_subtract = True, the master background will be applied.

--output_use_model

A boolean indicating whether to use the “filename” meta attribute in the data model to determine the name of the output file created by the step. Defaults to True.

--sigma_clip

Factor for sigma clipping outliers and contaminated spectra when combining MOS background spectra in the master_background_mos step. The value of sigma_clip will be used to set an outlier threshold for clipping any pixels in the background spectra that deviate from the median and median absolute deviation of the inputs before combining the background spectra. Setting sigma_clip to None will skip any outlier clipping. This parameter is only available in master_background_mos step and is not available in the generic master_background step. Defaults to 3.