Certain bands in the mm and sub-mm regime can be observed from Earth. The detector developments for e.g. HIFI are thus of use for ground based astronomy as well. In collaboration with NOVA, the Netherlands Research School for Astronomy, SRON participates in this transfer of technology for ALMA and before already for the precursor Champ+ instrument.
One of the largest and most ambitious projects in ground-based radio astronomy currently is ALMA, the "Atacama Large Millimeter Array", a mm and sub-mm wave interferometer consisting of 66 antennas being built in the Atacama desert in Northern Chile. It is expected to be fully operational in 2013. This project is a collaboration between Europe, the US, and Japan and presents major technical challenges for the design and construction of various components.
ALMA will be equipped with a number of frequency bands, ranging from 84 GHz to about 950 GHz (3.6 - 0.3 mm). Of the order 1000 receivers will be needed for the final array. The SIS heterodyne receivers for high frequencies (Band 9 at 650 GHz) have been designed and are currently being built by the NOVA-ALMA group at SRON Groningen with funding from NOVA.
Early Science observations are expected to commence in late 2011 with ~16 antennas equipped with all four "first light" receiver bands (including Band 9), baselines up to 1 km, and a representative set of correlator configurations.
- ALMA @SRON/NOVA
- ALMA @The Netherlands (Allegro)
- ALMA @Europe (ESO)
- ALMA @US (NRAO)
- ALMA @Japan (NAOJ)
For use at the APEX telescope of Germany in Chili, a precursor telescope to ALMA, an array instrument of the Max-Planck Institute für Radioastronomie in Bonn was upgraded (Champ -> Champ+). Two sets of array elements (each set consisting of 7 mixers) were made operational at 650 and 850 GHz. The mixers were designed and built by the NOVA group at SRON/LEA.