Blog

Our mirror in the test tower with its new pupil stop. This is a delrin cap which was bolted on the “tenet” by Derek and then we added a precision  mask to give a 0.29 central obscuration.

Thanks to the hard work of Armando, Marco and Runa the Magellan ASM has had its first round of flattening with the 4D interferometer in the test Tower. It took only one day from start to finish. The shell flattened very well, except in the central area which is hidden from light by the Magellan telescope’s central obscuration, so it does not matter.

Today we raised our hexapod-mounted adaptive secondary mirror (ASM) into the Arcetri test tower in Florence, Italy.  The large tower will allow us to operate the secondary at the same focal length and optical conjugates as the Magellan telescope in Chile.  We’ll use this test setup to interferometrically test the performance of our ASM and to close the loop on our full AO system.

The below image is our 92% Strehl Sloan r’ band image with our triplet ADC and dichroic beamsplitter in the beam.  The slight elongation of the PSF and the asymetric contrast of the fringes are due to the “zenith spike” effect of the ADC.  This effect is predicted by our models and will not manifest itself on-sky when the atmosphere will counteract the residual chromatism of the ADC.

Pictures from the fit check have been posted on flickr by the Magellan Observatory. Here’s a photo of the PI hard at work tweaking the handling cart.

More at their flickr page