Gaertner Plate Measurer

Year: 1952
Manufacturer: The Gaertner Scientific Corporation – Chicago (USA)
Materials: cast iron, steel, optical glass
Dimensions: L = 850 mm; P = 750 mm; H = 700 mm

Made in 1952 by the Gaertner Scientific Corporation in Chicago, this instrument allowed extremely precise measurements (up to 1 micron) of the position and size of celestial bodies on photographic plates. The plate is fixed on a central panel, while a sliding microscope allows pointing to the objects to be analyzed.

Relative positions are determined thanks to graduated scales and an advanced system that compensates for errors in the micrometer screw, ensuring high precision. To measure both celestial coordinates, the plate must be rotated by 90 degrees, an operation performed with an accuracy of a few arc seconds.

This instrument represented an example of high-precision engineering, indispensable for the detailed analysis of astronomical plates.