Step Arguments

The extract_1d step has five 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 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 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 reference file. If neither is specified, a value of 0 will be used.

--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 extract_1d reference file (if any) will be used. If not None, this parameter overrides the value in the extract_1d reference file.

--apply_nod_offset

This is a boolean flag to specify whether the target and background positions specified in the reference file should be shifted to account for nod and/or dither offset. If None (the default), the value in the reference file will be used, or it will be set to True if it is not specified in the reference file. The offset is determined by finding the location in the data corresponding to the target position (as given by keywords TARG_RA and TARG_DEC).

At the time of writing, a nod/dither offset will not be applied if the source is extended. It will also not be applied for wide-field slitless spectroscopy data, or NIRSpec fixed-slit, or NIRSpec MOS (MSA) data.