A high-resolution Fourier transform spectrometer for astronomical observations and development of wavelength standards

At the Institute for Astrophysics Goettingen (IAG), we are purchasing a high resolution Fourier Transform Spectrograph (FTS) for astronomical observations and development of calibration standards aiming at high wavelength precision. Astronomical spectrographs that work in the regime of very high resolution (resolving powers λ/δλ≥10 5 ) now achieve unprecedented precision and stability. Precise line shifts can be investigated to conclude for an objects radial velocity relative to the observer. As a long-term scientific goal, the evolution of galaxy redshift due to dark energy can be monitored. Also, the detection of lower mass, down to Earth-like planets will become feasible. Here, M-dwarfs are promising objects where an orbiting exo-Earth can cause a wavelength shift large enough to be detected. Emitting mainly in the near infrared (NIR), these objects require novel calibration standards. Current schemes under consideration are gas cathode lamps (e.g. CN, UNe) and a highly stable Fabry-Perot interferometer (FPI) to act as a cost-efficient alternative to the laser frequency comb (LFC, [1]). In addition to experiments exploring novel wavelength calibration types, light will be fed from our telescopes at IAG. A Vacuum Tower Telescope (VTT) for solar observations and the 50 cm Cassegrain telescope allow to investigate stellar and spatially resolved light at our facilities.