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

CCD Cameras


The signal-to-noise ratio (SNR) characterizes the quality of a measurement and determines the ultimate performance of the system. The three primary sources of noise in a CCD imaging system are photon noise, dark noise, and read noise, all of which must be considered in the SNR calculation.

CCD Cameras

FITS Files

FITS files are the end product of a CCD image of an astronomical object, and are designed to store data sets consisting of multi-dimensional arrays and 2-dimensional tables.