  We present an overview of the capabilities and key algorithms employed in the
so-called eMPT software suite developed for planning scientifically optimized,
multi-object spectroscopic (MOS) observations with the Micro-Shutter Array
(MSA) of the Near-Infrared Spectrograph (NIRSpec) instrument on board the James
Webb Space Telescope (JWST), the first multi-object spectrograph to operate in
space. NIRSpec MOS mode is enabled by a programmable MSA, a regular grid of
~250,000 individual apertures that projects to a static, semi-regular pattern
of available slits on the sky and makes the planning and optimization of an MSA
observation a rather complex task. As such, the eMPT package is offered to the
NIRSpec user community as a supplement to the MSA Planning Tool (MPT) included
in the STScI Astronomer's Proposal Tool (APT) to assist in the planning of
NIRSpec MOS proposals requiring advanced functionality to meet ambitious
science goals. The eMPT produces output that can readily be imported and
incorporated into the user's observing program within the APT to generate a
customized MPT MOS observation. Furthermore, its novel algorithms and modular
approach make it highly flexible and customizable, providing users the option
to finely control the workflow and even insert their own software modules to
tune their MSA slit masks to the particular scientific objectives at hand.

Instrumentation and Methods for Astrophysics