Luminosity, Temperature and Radius

By utilizing the Stefan-Boltzmann Law and the basic properties of a sphere's surface area, a star's luminosity, temperature, and radius can be mathematically related and thus used to calculate each other.


Why Study Variable Stars

From measuring the distances to galaxies to discovering new planets, studying variable stars allows us to refine our current understanding of astrophysics and get to the heart of how our universe works.



The Landolt catalog has become the de facto standard for transforming to the UBVR CIC system, and place photometric observations on a common platform.


Standard Photometric Stars

Photometric-standard stars are stars that have had their light output in various passbands of photometric system measured very carefully. They provide a means to not only calibrate your photometric system, but give a common “yardstick” from which all measurements can be compared.



Extinction is the removal of light through dust, gas, or atmosphere, or the overall dimming of starlight by interstellar matter. Extinction comes in two types: Interstellar and Atmospheric.


Comparison Stars

Comparison stars provide a baseline from which to compare with, and it is important that comp stars are stable and un-variable. Software such as AstroImageJ can help locate comparison stars.


WCS Coordinates

The World Coordinate System (WCS) is the RA and Dec embedded in a FITS image. Multiple tools, such as and MaximDL can insert WCS coordinates into the image