Constraining intrinsic $\nu_e$ events in the MiniBooNE beam*

MiniBooNE is a short baseline neutrino experiment at Fermilab looking for $\nu_{\mu} \rightarrow \nu_e$ oscillations in the region of the LSND signal. The neutrino beam is 99\% pure muon flavor neutrinos from pion and kaon decays, however, kaons in the beam also decay to produce electron neutrinos. These ``intrinsic'' electron neutrinos are an important background to the electron neutrino appearance search. This talk will present how MiniBooNE constrains the number of kaons in the beam, and the number of ``intrinsic'' electron neutrino events.