https://obs-web.rs.umbc.edu/ 2026-08-01T11:19:11+00:00 https://obs-web.rs.umbc.edu/ https://obs-web.rs.umbc.edu/lib/tpl/bootstrap3/images/favicon.ico text/html 2023-11-11T19:42:51+00:00 Anonymous (anonymous@undisclosed.example.com) https://obs-web.rs.umbc.edu/doku.php?id=wiki:astronomy:coordinate_systems&rev=1699749771&do=diff Angles on the Sky Primer on Spherical Coordinates. Horizontal Coordinate System Discuss Altitude and Azimuth, discuss poles, fundamental plane. Discuss issues with this system for astro purposes. Equatorial Coordinate System Discuss degrees of arc, arc mins, arc secs. text/html 2025-01-13T16:01:09+00:00 Anonymous (anonymous@undisclosed.example.com) https://obs-web.rs.umbc.edu/doku.php?id=wiki:astronomy:magnitude&rev=1736802069&do=diff The radiative energy of a source can be given either in relative terms via some magnitude scale or in absolute terms via some measure of radiative quantities. ---------- The Greek astronomer Hipparchus is usually credited with the origin of the magnitude scale. He assigned the brightest stars he could see with his eye a magnitude of $1$$6$$6\times$$100\times$$100\times$$100^{1/(6-1)} = 2.512$$2$$2.512^1\times=2.512\times$$1$$6$$2.512^2\times=6.3\times$$4$$25$$2.512^5\times=100\times$$20$$2.512… text/html 2025-01-13T16:01:02+00:00 Anonymous (anonymous@undisclosed.example.com) https://obs-web.rs.umbc.edu/doku.php?id=wiki:astronomy:radiative_quantities&rev=1736802062&do=diff The radiative energy of a source can be given either in relative terms via some magnitude scale or in absolute terms via some measure of radiative quantities. ---------- We know from physics classes that energy is conserved quantity. This makes it a convenient quantity to work with because we can be very clear about defining systems containing sources or sinks that add or remove energy to said system, respectively.$E$$[E]=Joules,J$$erg$$1 ~erg \equiv 100~ nJ$$L$$[L]=Watts,W$$F$$[F]=W(m^2)^{-1}…