  Galactic interstellar emission contributes substantially to Fermi LAT
observations in the Galactic plane, the location of the majority of supernova
remnants (SNRs). To explore some systematic effects on SNRs' properties caused
by interstellar emission modeling, we have developed a method comparing the
official LAT interstellar emission model results to eight alternative models.
We created the eight alternative Galactic interstellar models by varying a few
input parameters to GALPROP, namely the height of the cosmic ray propagation
halo, cosmic ray source distribution in the Galaxy, and atomic hydrogen spin
temperature. We have analyzed eight representative SNRs chosen to encompass a
range of Galactic locations, extensions, and spectral properties using the
eight different interstellar emission models. We will present the results and
method in detail and discuss the implications for studies such as the 1st Fermi
LAT SNR Catalog.
