  Since pulsating subdwarf B (sdBV or EC14026) stars were first discovered
(Kilkenny et al, 1997), observational efforts have tried to realize their
potential for constraining the interior physics of extreme horizontal branch
(EHB) stars. Difficulties encountered along the way include uncertain mode
identifications and a lack of stable pulsation mode properties. Here we report
on Feige~48, an sdBV star for which follow-up observations have been obtained
spanning more than four years, which shows some stable pulsation modes.
  We resolve the temporal spectrum into five stable pulsation periods in the
range 340 to 380 seconds with amplitudes less then 1%, and two additional
periods that appear in one dataset each. The three largest amplitude
periodicities are nearly equally spaced, and we explore the consequences of
identifying them as a rotationally split $\ell=1$ triplet by consulting with a
representative stellar model.
  The general stability of the pulsation amplitudes and phases allows us to use
the pulsation phases to constrain the timescale of evolution for this sdBV
star. Additionally, we are able to place interesting limits on any stellar or
planetary companion to Feige~48.
