Basic Photometry Tutorials for GTN Participants
Photometry -the study of astronomical object’s brightness as a function of time. One standard result of photometry is the light curve .
Photometry Lingo
Magnitude is a logarithmic measure of the brightness of an object. Dim objects have magnitudes which are large positive numbers. Bright objects have magnitudes which are small positive or negative numbers. The magnitudes of the brightest objects are large negative numbers. This system applies to visible, IR, and near UV light. The equation used by modern astronomers to define the difference in magnitude between two sources
is: m1-m2 = -2.5 log (L1/L2), where m1 and m2 are the magnitudes of the two sources, and L1 and L2 are their brightnesses.
Luminosity: the measured energy emitted each second by a celestial body.
This applies to all wavelengths of light.
Fluence: the integrated luminosity over some specified time duration.
Photon Flux: the number of photons emitted per second that are detected in a square meter-sized detector.
Energy flux: the energy emitted per second (luminosity) that is deposited in a square-meter sized detector.
How to determine Brightness of an object: Cookie Cutter Photometry
Complete this activity to get a basic understanding of photometry.
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