FTP, name the apparent displacement of an observed object due to a change in the observer's position.
The introduction of a photographic method by Frank Schlesinger in 1903 considerably improved the accuracy of measurement for this quantity, and, in 1989, the European Sapce Agency launched a satellite called Hipparcos specifically to achieve more precise values. The diurnal form, caused by the Earth's rotation, is accounted for in astronomical measurements, along with the annual type.  Friedrich Bessel made the first stellar measurement, obtaining a value of 1/3 arc second for 61 Cygni. FTP, name the apparent displacement of an observed object due to a change in the observer's position.
The introduction of a photographic method by Frank Schlesinger in 1903 considerably improved the accuracy of measurement for this quantity, and, in 1989, the European Sapce Agency launched a satellite called Hipparcos specifically to achieve more precise values.
parallax (accept stellar parallax before "diurnal form")