Radial Velocity

A measure of movement towards or away from the observer, radial velocity is just one component of stellar motion that is derived through measurement of the doppler effect.


Astrometry Overview

Astrometry is the area that deals with the positions and motions of celestial objects. It has two main scientific objectives to provide: A stellar reference frame to which the motions of celestial objects (Solar System and beyond) may be referred Basic...


Telescopes: An Overview

Telescopes gather light from objects, and there are two main types: refractor (uses a lens to bend light) and reflector (uses a mirror to reflect light). Aperture and field of view are two main parameters of telescopes.


Proper Motion

Proper motion is the change in (x, y) tangential motion of a star, and described in two coordinates: Right Ascension and Declination



Parallax is the apparent shift in position of an object because of a change in the point of view. Closer objects have a larger parallax than farther objects.


Color and Temperature

Star color is based on its temperature (hotter stars are blue, while cooler stars are red), and the color/temperature of a star can be classified into stellar classes


Wien’s Law

Wein's Law relates light intensity to temperature, stating that the peak wavelength is the inverse of temperature, and temperature and intensity are directly correlated.

Light Curves

Light Curve O-C Diagrams

The O-C, or Observed-Computed method studies period changes in variable stars by comparing the observed time of maximum brightness to the computed time. The O-C method is reflective of the cumulative effect of period changes.

Light Curves

Overview of a Light Curve

Light curves are graphs plotting the light output of an object over time, and are developed by taking images of an area repeatedly, using software to measure brightness over time, and graphing the points.


Stellar Motions

Stellar motions divide star movement into three categories: radial motion, proper motion, and a combination of the two (space motion).


Celestial Coordinates

Similar to latitude and longitude, Right Ascension and Declination define the celestial coordinate system used to locate and place celestial objects.


Instrumental Magnitude

Instrumental magnitude is derived from the raw counts of a CCD image, and can be combined with other measurements to achieve both apparent and absolute magnitude.