A view of the VLT. Credits: ESO/H.H. Hever IAP researchers are heavy users of astronomical observatories, on the ground and in space. On the ground, they observe at the European Southern Observatory (ESO) with its “Very Large Telescope” (VLT) in Chile, the Canada France Hawaii Telescope (CFHT) in Hawaii, and the Institut de Radio Astronomie Millimétrique (IRAM) radio-telescopes in France and Spain. They also observe, remotely, with space telescopes such as Hubble, XMM/Newton, Spitzer and Herschel and Planck. For years, there have been noticeable changes in observational programs with much greater sample sizes and a greater focus on observing at multiple wavelengths. These programmes require long-term observations, and take up a significant amount of the available time at these observatories. These changes require the setting up of international teams which make multiple observing proposals on many different telescopes, all for the same scientific goal. IAP researchers are key actors, and are sometimes the principal investigators of these programmes. They are named “Large programme”, “Key programme” or “Legacy programme”, as appropriate.