Observing the Galactic Halo with HaloSat

HaloSat is a CubeSat that is performing an all-sky survey of soft X-ray line emission from highly ionized oxygen in order to study the hot (~10⁶ K) circumgalactic medium (CGM) of the Milky Way. The goal is to determine the geometry of the CGM in order to provide insight into how it is fed and energized and also to estimate the total mass of the CGM to determine if it contains a cosmologically important reservoir of baryons. We present preliminary results from the first year of data on the spatial dependence of the halo emission measure and temperature. HaloSat data is currently being archived at the HEASARC and will be publicly available for analysis by the astronomical community.