.. _bkg_step_args:

Step Arguments
==============
The background image subtraction step has two optional arguments.
They are used in the process of creating an average background image, to
control the sigma clipping, and are passed as arguments to the astropy
``sigma_clip`` function:

``--sigma``
  The number of standard deviations to use for the clipping limit.
  Defaults to 3.

``--maxiters``
  The number of clipping iterations to perform, or ``None`` to clip until
  convergence is achieved. Defaults to ``None``.