# Step Arguments¶

The extract_1d step has six step-specific arguments.

--smoothing_length

If smoothing_length is greater than 1 (and is an odd integer), the background will be smoothed in the dispersion direction with a boxcar of this width. If smoothing_length is None (the default), the step will attempt to read the value from the EXTRACT1D reference file. If a value was specified in the reference file, that will be used. Note that in this case a different value can be specified for each slit. If no value was specified either by the user or in the EXTRACT1D reference file, no background smoothing will be done.

--bkg_order

This is the order of a polynomial function to be fit to the background regions. The fit is done independently for each column (or row, if the dispersion is vertical) of the input image, and the fitted curve will be subtracted from the target data. bkg_order = 0 (the minimum allowed value) means to fit a constant. The user-supplied value (if any) overrides the value in the EXTRACT1D reference file. If neither is specified, a value of 0 will be used. If a sufficient number of valid data points is unavailable to construct the polynomial fit, the fit will be forced to 0 for that particular column (or row).

--log_increment

Most log messages are suppressed while looping over integrations, i.e. when the input is a CubeModel or a 3-D SlitModel. Messages will be logged while processing the first integration, but since they would be the same for every integration, most messages will only be written once. However, since there can be hundreds or thousands of integrations, which can take a long time to process, it would be useful to log a message every now and then to let the user know that the step is still running.

log_increment is an integer, with default value 50. If it is greater than 0, an INFO message will be printed every log_increment integrations, e.g. “… 150 integrations done”.

--subtract_background

This is a boolean flag to specify whether the background should be subtracted. If None, the value in the EXTRACT1D reference file (if any) will be used. If not None, this parameter overrides the value in the reference file.

--use_source_posn

This is a boolean flag to specify whether the target and background extraction region locations specified in the EXTRACT1D reference file should be shifted to account for the expected position of the source. If None (the default), the step will make the decision of whether to use the source position based on the observing mode and the source type. The source position will only be used for point sources and for modes where the source could be located off-center due to things like nodding or dithering. If turned on, the sky (RA/Dec) position of the source is used in conjunction with the World Coordinate System (WCS) to compute the x/y source location. For long-slit type modes (e.g. MIRI LRS and NIRSpec fixed-slit and MOS), only the position in the cross-dispersion direction is used to potentially offset the extraction regions in that direction.

--apply_apcorr

Switch to select whether or not to apply an APERTURE correction during the Extract1dStep processing. Default is True