Spectro-imaging of the extreme-UV solar corona
Abstract
This paper describes an instrument concept for imaging spectroscopy of ultraviolet (UV) line emission from the solar corona, in the (30-120) nm wavelength range. The optical design for this Ultraviolet Spectro-Coronagraph (UVSC) instrument concept is an externally occulted, off-axis Gregorian telescope where the secondary mirror is a Toroidal Varied Line-Space (TVLS) grating. A field stop with multiple slits is at the prime focus of the telescope's mirror. This multi-slit field stop is the entrance aperture for the spectrograph. The slits select a number of strips in the field-of-view (FOV) with enough separation to minimize the spectral overlap of the UV lines dispersed by the TVLS grating. The complete two-dimensional imaging of the FOV is obtained by interpolating the slit images along the spectral dispersion direction. This paper discusses the use of an UVSC instrument on HERSCHEL, a NASA sounding-rocket payload. HERSCHEL includes the Sounding-rocket CORonal Experiment (SCORE) that currently comprises a UV Coronagraphic Imager (UVCI) for narrow-band (i.e., λ/Δλ≈10) imaging of the HeII, 30.38 nm, line. Adding a spectroscopic capability (i.e., λ/Δλ ≈ 0.3-1 × 104) to the UVCI would enhance the HERSCHEL's science. This paper presents the ray-tracing results of the expected spectral and spatial performances of a UVSC/SCORE optimised for the HeII, 30.38 nm, line.
- Publication:
-
Solar Physics and Space Weather Instrumentation
- Pub Date:
- August 2005
- DOI:
- 10.1117/12.617659
- Bibcode:
- 2005SPIE.5901..289F