NationMaster - Encyclopedia: Besselian epoch

A Besselian epoch, named after the German mathematician and astronomer Friedrich Bessel (1784 _ 1846), is an epoch that is based on a Besselian year, which is a tropical year measured at the point where the Sun's longitude is exactly 280�.

Since 1984, Besselian epochs have been superseded by Julian epochs. The current standard epoch is J2000.0, which is a Julian epoch.

Besselian epochs are calculated according to:

B = 1900.0 + (Julian date - 2415020.31352)/365.242198781

The standard epoch that was in use before the current standard epoch (J2000.0) was B1950.0, a Besselian epoch.

Categories: Astronomy | Celestial coordinate system | Astronomy stubs

Results from FactBites:

Glossary of astronomical terms (3582 words)
	Either of the two points (vernal, autumnal) on the celestial sphere where the ecliptic (which is the apparent path of the sun on the sky) intersects the celestial equator.
	See separate definitions for Besselian year and Julian year.) The differences in an object's position when given in equinoxes 1950.0 and 2000.0 amounts to several arc minutes.
	The diminishing of light from astronomical objects due to the earth's atmosphere, in which molecules (air, dust, etc.) of the atmosphere absorb, reflect, and refract light before it reaches the ground.

More results at FactBites »

COMMENTARY

Share your thoughts, questions and commentary here

Want to know more?
Search encyclopedia, statistics and forums:

Feeds | Contact
The Wikipedia article included on this page is licensed under the GFDL.
Images may be subject to relevant owners' copyright.
All other elements are (c) copyright NationMaster.com 2003-5. All Rights Reserved.
Usage implies agreement with terms, 1022, m