Abstract:
Hanle echelle spectrograph (HESP) is a high resolution, bench mounted, fiber-fed spectrograph at visible wavelengths. The instrument was recently installed at the 2m Himalayan Chandra Telescope (HCT), located at
Indian Astronomical Observatory (IAO), Hanle at an altitude of 4500m. The telescope and the spectrograph
are operated remotely from Bangalore,(∼ 3200km from Hanle), through a dedicated satellite link. HESP was
designed and built by Kiwi Star Optics, Callaghan Innovation, New Zealand. The spectrograph has two spectral
resolution modes (R=30000 & 60000). The low resolution mode uses a 100 micron fiber as a input slit and the
high resolution mode is achieved using an image slicer. An R2 echelle grating, along with two cross dispersing
prisms provide a continuous wavelength coverage between 350-1000nm. The spectrograph is enclosed in a thermally controlled environment and provides a stability of 200m/s during a night. A simultaneous thorium-argon calibration provides a radial velocity precision of 20m/s. Here, we present a design overview, performance and commissioning of the spectrograph.
