We continue to work closely with JCMT staff in Hawaii on improving the surface accuracy of the antenna using ``holographic'' measurement techniques with millimetre-wave signals. Debenham has developed a new set of software for carrying out the phase-retrieval analysis which provides more flexibility and better diagnoses of errors. This has been used in studies of thermal deformations and of the ``scalloping" of the panels. The new graphical features also revealed that significant measurement errors are being caused by multi-path reflections from the membrane in front of the antenna. Ways of removing the these effects are being investigated.
We are also collaborating with the Köln group on measuring their new submillimetre antenna on the Gornergrat (KOSMA) using similar techniques.