  In this report, we present the results of our analysis of trace position
changes during NIRISS/SOSS observations. We examine the visit-to-visit impact
of the GR700XD pupil wheel (PW) position alignment on trace positions for
spectral orders 1 and 2 using the data obtained to date. Our goal is to improve
the wavelength solution by correlating the trace positions on the detector with
the PW position angle. We find that there is a one-to-one correspondence
between PW position and spectral trace rotation for both orders. This allowed
us in turn to find an analytic model that is able to predict a trace
position/shape as a function of PW position with sub-pixel accuracy of about
~0.1 pixels. Such a function can be used to predict the trace position in low
signal-to-noise ratio cases, and/or as a template to track trace position
changes as function of time in Time Series Observations (TSOs).
