  The magnetic beta Cep pulsator xi^1 CMa has the longest rotational period of
any known magnetic B-type star. It is also the only magnetic B-type star with
magnetospheric emission that is known to be modulated by both rotation and
pulsation. We report here the first unambiguous detection of a negative
longitudinal magnetic field in xi^1 CMa (<Bz>=-87 +/- 2 G in 2019 and <Bz>=-207
+/- 3 G in 2020), as well as the results of ongoing monitoring of the star's
Halpha variability. We examine evidence for deviation from a purely dipolar
topology. We also report a new HST UV spectrum of xi^1 CMa obtained near
magnetic null that is consistent with an equatorial view of the magnetosphere,
as evidenced by its similarity to the UV spectrum of beta Cep obtained near
maximum emission. The new UV spectrum of xi^1 CMa provides additional evidence
for the extremely long rotation period of this star via comparison to archival
data.
