Glossary

Seeing

The blurring effect caused by Earth’s turbulent atmosphere that limits the sharpness of astronomical images, typically measured in arcseconds.

FWHM

(Full Width at Half Maximum) A measurement of the width of a star’s profile at half its maximum brightness, commonly used to quantify seeing conditions and image quality.

PSF

(Point Spread Function) The response of an imaging system to a point source like a star, showing how starlight is spread out by the combination of optics, atmosphere, and detector characteristics.

WCS

(World Coordinate System) A set of mathematical transformations that maps pixel positions in an astronomical image to precise celestial coordinates (right ascension and declination).

Centroiding

The process of determining the precise center position of a stellar image to sub-pixel accuracy, essential for accurate photometry and astrometry.

Exposure

The process of collecting light on an astronomical detector for a specified duration, determining how much light is gathered from celestial objects.