FURST

The Full-sun Ultraviolet Rocket Spectrometer (FURST) is a NASA sounding rocket spectrograph that measures the far-ultraviolet spectrum of the Sun as a star, from about 120 to 180 nm at a resolving power above 20,000.

Hubble has given us higher-resolution ultraviolet spectra of other stars than we have of the Sun viewed as a single point of light. FURST closes that gap, so that the Sun can be compared directly with the stars Hubble observes. The principal investigator is Charles Kankelborg.

The design

FURST is a Rowland-circle spectrograph with as few optical surfaces as possible. Instead of a slit, an array of small cylindrical mirrors feeds seven channels onto a single grating, made by Carl Zeiss Jena, and a single CCD.

My role

I worked on the optical design of FURST, and wrote software to model it and analyze its tolerances. My package furst models the instrument both as designed and as built, using measurements of the flight grating, coatings, and filter to predict its effective area and spectral resolution.