Image Details
Caption: Figure 19.
Fiducial point sources, embedded throughout the array, constrain optical plate scale and distortion polynomials. Each fiducial has four etched pinholes and is backlit by a 470 nm LED. FIFs are mounted directly to the petal, like the positioners. Two fiducials per petal are mounted to the GFA housing (GIFs; not pictured).
© 2022. The Author(s). Published by the American Astronomical Society.