From Idea to Reality Sites In order to observe objects continuously for long periods of time from the ground, it is necessary to have a network of telescopes. SONG will have 8 identical network nodes distributed in the northern and southern hemispheres at already existing observatories, making it possible to observe stars over the entire sky. Eight nodes are required in order to ensure a sufficient time-coverage during observations. The figure below shows a possible allocation of nodes for SONG. Instruments The main instrument at each observatory will be a highly efficient spectrograph, optimised for measuring accurate radial velocities for the star under study. This instrument will receive light from a single large telescope or from several smaller ones. The baseline design of SONG for several reasons includes the use of 4 telescopes of 50cm diameter at each site: By choosing smaller telescopes while still maintaining the scientific performance, the construction will be cheaper and transport and maintenance will be less complicated than for a large telescope. There are several commercial vendors who are capable of delivering the types and size of telescopes we need. For such solutions the basic software for controlling the telescope has already been developed and tested. This is a very significant advantage. Likewise, the construction of an efficient spectrograph for a small telescope is less complicated and cheaper than for a big telescope. Using several telescopes allows us to eliminate the long-term drift, by observing an object simultaneously with a number of telescopes at different sites. In this way we will be able to improve the long-term stability currently existing in spectrographs. This is a very important capability of SONG. Several team members have direct expertise in the construction of high-resolution and high-performance spectrographs. The telescopes and spectrograph for each site will be transported in standard shipping containers. This has several advantages: easy, cheap and safe transport the container will remain on-site to serve as weatherproof office and workshop. The GONG network has already used this design strategy successfully. One of the eight SONG-units consisting of the container which also is used as an office and the building for the four 50cm telescopes. 3D-Animation of the SONG Site AVI format (DivX 5.1) - Size: 2,8 MB      AVI format (DivX 5.1) - Size: 4 MB MPG format - Size: 2,1 MB       MPG format - Size: 8,5 MB The data recorded from the observations will be approximately 20Gb per day. It will be automatically processed at the local observatory site and transferred to the network control centre via the internet. All containers and instruments will be set up at a central site for testing and evaluation before transporting them to the observatory sites for deployment. This will ensure the right performance of the equipment and instruments and reduce the time needed at each site for setup and testing. Other Projects Several other projects with complementary scientific aims as SONG are currently operating or under development. MOST / WIRE These two satellite missions are currently operating. MOST is dedicated to asteroseismology and measuring oscillations using photometry, while WIRE since 1999 has been observing its targets with an onboard camera. Neither satellite is able to measure oscillation amplitudes as small as those in the SONG target stars. COROT / Kepler Two satellite missions (launch dates in 2006, 2008) which will search for planets around other stars, in particular planets approaching the mass and radius of Earth, and do asteroseismology. However their targets are generally somewhat fainter than our targets. Since both missions use the occultation method (planet transit) for finding planets, they will mainly be sensitive to the size (i.e. radius) of the planets detected, while SONG will be sensitive to the mass. GONG / BiSON Ground based networks of telescopes dedicated to the study of solar oscillations. Both have been operating for more than 10 years by now and provide important information on the behaviour of the Sun and its oscillations. SoHO Solar and Heliospheric Observatory, satellite mission studying the Sun and its properties. Three of its twelve instruments are dedicated to the study of solar oscillations. The mission is estimated to continue until 2009. It is important to note that the current level of understanding of the Sun and the detailed testing of solar models have only been possible due to the data from the observations of oscillations with the BiSON / GONG networks and the SoHO satellite. Budget Since the network is ground-based, the total budget for the construction of SONG will be significantly smaller than for a space-based project. There will be three main components to SONG's budget per node: Telescope(s)     EUR 200000,- Spectrograph (including detector)     EUR 300000,- Sites, infrastructure, logistics     EUR 100000,- Total     EUR 600000,- The total budget for construction of the network will be 5 Million Euros. This estimate does not take into account the potential price reductions when buying large quantities. Project Timeline The SONG network will be completed and begin its observations in 2009.