The telescopes has a diameter of 0.7m - 1m. A small aperture telescope is sufficient to obtain data of the required quality, as the purpose of SONG is the study of bright stars, those you roughly can see with your naked eye.
The 1m telescope at the Teide Observatory is build by ASTELCO Systems GmbH.
The 1m telescope at the Lenghu Observatory is build by Nanjing Institute of Astronomical Optics & Technology (NIAOT).
The two 70cm telescopes at the Mt. Kent Observatory are from PlaneWave Instruments.
The 1m telescope at the Apache Point Observatory is build by PlaneWave Instruments.
A spectrograph is an instrument that separates light into its different colours, operating in a manner not unlike the droplets of rain that create a rainbow. Light from distant stars enters the spectrograph and will be spread out into all the different colours, allowing us to study them individual. The colours (or wavelengths) carry information about the stars and can be used to determine their mass, size and chemical composition, among other things.
The picture to the right shows how the output (a spectrum) from the spectrograph looks. Numerous dark lines can be seen. These are called spectral lines. By making very precise measurements of their position, we can determine the surface velocity of the stars we observe through the Doppler effect. We can measure the velocity to a precision of 1-2m/s, which corresponds to a shift of ~100 atoms in the position of the spectral lines on the digital camera in the spectrograph.
