Unique view of the 4MOST focal plane
by Henri Boffin on 2023-07-20
This photo was taken in the AIP Integration hall on 19 July 2023. It shows an amazing view of the 4MOST focal plane as seen through the Wide Field Corrector (WFC) from the perspective of the telescope’s secondary mirror. The hexagonal pattern of bright dots in the centre shows the area of the AESOP spines. Just outside the spines, visible as bright squares, one can recognise the six technical CCDs (guiders and wavefront sensors) through their pickup prisms. The bright rings are the fiducials used by the 4MOST metrology system to precisely measure the position of the spines. One can also spot the baffles inside the WFC as faint concentric rings outside the focal plane.
This is a rare occasion to enjoy such a view. It further demonstrates that 4MOST is complete and ready for verification in the AIP Integration hall!