  The current STELLA Echelle spectrograph (SES), which records 390nm to 870nm
in one shot at a spectral resolution of 55000, will be replaced by a suite of
specialized spectrographs in three spectral bands. The UV will be covered by a
newly designed H&K spectrograph covering 380nm to 470nm (SES-H&K), the visual
band (470nm - 690nm) will be covered by SES-VIS, which is a vacuum-stabilized
spectrograph designed for high radial-velocity accuracy, and the NIR will be
covered by the current SES spectrograph from 690nm to 1050nm. In order to
improve the UV transmission, and to accommodate three different fibre-feeds,
the prime focus corrector of the telescope will be refurbished, leading to an
optical system with the f/2 1200mm spherical primary, a 4-lens collimator with
2 arcsec aperture, atmospheric dispersion corrector (ADC), and two dichroic
beam splitters, feeding 3 separate fibre feeds for the three bands. The newly
designed H&K spectrograph will be an Echelle spectrograph, based on a
R4-grating with 41.6 l/mm and 110mmx420mm, using a f/5 camera and the
cross-disperser in double pass (as in TRAFICOS, MIKE, KPF), using 21 spectral
orders. The spectral resolution of all three spectrographs will be comparable
to the 55000 of the current SES.
