The darkness and quality of the sky at Calar Alto Observatory is outstanding not only for astronomical observations in visible light, but also in the infrared. A recent study based on an extensive data set demonstrates that Calar Alto summit occupies one of the world leading places among the darkest astronomical observatories in the infrared. This analysis complements a previous scientific study centred on observations in visible light. It is confirmed that the fraction of useful time for astronomical observations at Calar Alto is around 70%...

Astronomers have used light echoes as a time machine to unearth secrets of one of the most influential events in the history of astronomy –a stellar explosion witnessed on Earth more than 400 years ago. By using a Galactic cloud as interstellar “mirror” an international team led by Oliver Krause of the Max Planck Institute for Astronomy in Germany has now re-analysed the same light seen on Earth in the 16th century and have, for the first time, determined the exact type of explosion that happened. Calar Alto Observatory has contributed to this discovery and these results were published in the scientific journal Nature, 4th December 2008 issue...

Calar Alto nights enjoy excellent conditions and extremely clear skies. Especially in the winter season, clouds and fog very often stay below the observatory's height of 2168 m above sea level. Prominent topographic features like the mountains of Sierra Nevada, approximately 70 km to the west of Calar Alto, appear as clear and sharp as if they were next door, and on a good night one can see Africa towards the south. In this photo release we offer two recent photographs that illustrate these facts...