Sounding rocket payload designed for investigations of the distribution and dynamics of the hot component of the interstellar medium using a field-widened spatial heterodyne spectrometer

We are developing a field-widened spatial heterodyne spectrometer (SHS) for suborbital observations of the hot component of the diffuse interstellar medium. Our goal for these observations is to obtain the first velocity-resolved (20 km/s) line profiles of the C IV 154.8, 5.1 nm emission line from the Cygnus loop and from one direction at high galactic latitude. Long term, our interest is to develop an SHS instrument for a radial-velocity-resolved sky survey of the 105 K 'coronal gas' in the interstellar medium using a small satellite. This paper reviews the scientific motivation and SHS concept and then discusses in more detail the optical design of the sounding rocket payload and the data taking strategy for the observations.