The optical design of the Southern African large telescope high resolution spectrograph: SALT HRS

Direct evidence for shock-powered optical emission in a nova

“…We obtained optical spectroscopic observations spanning from day 5 up to day 405 after eruption using the Ultraviolet and Visual Echelle Spectrograph (UVES) on the VLT UT2 telescope of the European Southern Observatory ( [20][21][22][23] ). UVES covers the wavelength range 3800 -10,000Å at a resolution R ≈ 59, 000, HERCULES covers the range 4000 -10,000Å at a resolution R ≈ 41, 000, and HRS was used in the HR mode covering 3800 -9000Å at a resolution R ≈ 67, 000.…”

“…The GeV γ-ray flux reached 2.1 × 10 −9 erg cm −2 s −1 on days 25 and 29, making V906 Car the brightest γ-ray nova to date 18,19 . Current theory suggests that the GeV γ-rays originate from shocks internal to the nova ejecta-specifically as a fast biconical wind slams into a slower equatorial torus 20,21 . The shocks accelerate particles to relativistic speeds and γ-rays are produced when these relativistic particles interact with either the surrounding medium or seed photons 22,23 .…”

“…Our high-resolution optical spectra (SI.2) and light curves, lead us to suggest the following scenario for V906 Car. A dense slowly-expanding torus (with an expansion velocity v 1 < 600 km s −1 ) is ejected in the binary's orbital plane during the first days of the eruption 20 . This torus has complex density structure, consisting perhaps of a spiral or multiple shells 29 .…”

Handling observation proposals for SALT

“…5 A third instrument will be the High Resolution Spectrograph. 6 In addition, an auxiliary instrument port for visitor instruments is available.…”

Off-axis Two-mirror System with Wide Field of View Based on Diffractive Mirror

“…Fortunately, we can obtain more and more news of progress of the successful manufacture and application of large-size DOEs. In Southern African Large Telescope (SALT), an echelle grating with the size of 204 mm × 407 mm was applied in the high resolution spectrograph [14]; an echelle grating with a size of 267 mm × 1067 mm，a blaze angle of 76° was applied in Airborne InfraRed Echelle Spectrometer (AIRES) [15]; In addition, University of Rochester developed a large-aperture grating tiling method, and this method was successfully used for tiling a tiled-grating assembly composed of three full-size gratings (470 mm × 430 mm, 500 mm in diagonal) with interferometric precision [16]. Furthermore, LLNL (Lawrence Livermore National Laboratory) has manufactured a large area grating with a size of 910 mm × 420 mm, and PGL (Plymouth Grating Laboratory) also has manufactured a large area grating with a size of 910 mm × 450 mm [17].…”