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Instruments at Tenerife

The SONG telescope

The 1.0m alt-az mounted Cassegrain telescope is manufactured by ASTELCO Systems GmbH. It can slew between objects with a speed of up to 20 º/s and has a pointing accuracy of less than 3'' RMS. The primary mirror is relatively thin, only 5 cm, and is actively controlled based on Shack-Hartmann measurements.

The third mirror can rotate 180º which allows two Nasmyth foci.

The SONG spectrograph

The primary use of the spectrograph is to determine radial velocities of stellar surfaces for  asteroseismic analysis. The spectrograph is s a high resolution echelle spectrograph operating in the range from 35.000 – 112.000 of resolution. Normal operation is around 100.000. The average dispersion is 0.02Å/pixel and the wavelength range is about 4400-6900Å with full spectral coverage at wavelengths below 5300Å. The detector used is a commercial CCD camera developed by Andor and the model is Ikon-L where the chip size is 2k x 2k. This camera has a fast readout speed of 3MHz leading to 2.3s readout time which helps to improve observing efficiency.

The spectrograph has a dedicated guide system which uses two movable mirrors to correct for atmospheric disturbance (tip/tilt) and small misalignments in the long coudé path. The speed of which the guide system can do corrections is limited by the brightness of the targets and the frame rate at which the cameras can operate (which is about 50Hz). The optimal telescope focus is also determined by the guide system.

An iodine cell and a Thorium-Argon lamp can be used for wavelength calibration.

The SONG Lucky Imaging cameras

Lucky imaging (LI) will be used mainly to study gravitational micro-lensing events towards the galactic center. The LI CCD model in use is an Andor iXON modelnumber 897. This model has a frame rate of up to 33 Hz which is crucial for doing LI.

The CCD chip size is 512 x 512 pixels and the field-of-view is about 40'' with a pixel scale of 0.08'' per pixel.


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