What is the pointing accuracy of Hubble in arcseconds?

Hubble’s pointing accuracy is 0.007 arcseconds. That figure describes how steadily the telescope can remain aimed at a target, not the telescope’s optical resolution or the size of a single pixel.

Hubble achieves this precision with its Fine Guidance Sensors, gyroscopes, reaction wheels, and computer-controlled pointing systems. The sensors lock onto guide stars and make continual corrections so the observatory can hold a distant target almost motionless during long exposures.

An arcsecond is an extremely small angle: 1 degree contains 3,600 arcseconds. Hubble’s 0.007-arcsecond stability is therefore far finer than the telescope’s roughly 0.05-arcsecond diffraction-limited resolution in visible light. The two numbers are often confused: pointing accuracy concerns aim and steadiness, while resolution concerns the smallest details the optics can distinguish.

NASA illustrates the precision by comparing it with keeping a laser aimed at a dime roughly 200 miles away. This steadiness is essential for sharp images of faint galaxies, nebulae, planets, and other moving or distant targets.