  To fully characterize the atmospheres, or lack thereof, of terrestrial
exoplanets we must include the high-energy environments provided by their host
stars. The nearby mid-M dwarf LHS 3844 hosts a terrestrial world which lacks a
substantial atmosphere. We present a time series UV spectrum of LHS 3844 from
1131-3215A captured by HST/COS. We detect one flare in the FUV, which has an
absolute energy of 8.96+/-0.79e28 erg and an equivalent duration of 355+/-31 s.
We extract the flare and quiescent UV spectra separately. For each spectrum we
estimate the Ly-alpha flux using correlations between UV line strengths. We use
Swift-XRT to place an upper limit on the soft X-ray flux and construct a
differential emission model (DEM) to estimate flux that is obscured by the
interstellar medium. We compare the DEM flux estimates in the XUV to other
methods that rely on scaling from the Ly-alpha, Si IV, and N V lines in the UV.
The XUV, FUV, and NUV flux of LHS 3844 relative to its bolometric luminosity is
log10(Lband/LBol) = -3.65, -4.16, and -4.56, respectively, for the quiescent
state. These values agree with trends in high-energy flux as a function of
stellar effective temperature found by the MUSCLES survey for a sample of
early-M dwarfs. Many of the most spectroscopically accessible terrestrial
exoplanets orbit inactive mid- to late-M dwarfs like LHS 3844. Measurements of
M dwarf high-energy spectra are preferable for exoplanet characterization, but
are not always possible. The spectrum of LHS 3844 is a useful proxy for the
current radiation environment for these worlds.
