for January 0.9235, 1950 TT Besselian years (see below), e.g., 1950.0 or B1950.0 for January 0.9235, 1950 TT Julian years, e.g., J2000.0 for January 1...

equinox and of the epoch. The currently used standard equinox and epoch is J2000.0, which is January 1, 2000 at 12:00 TT. The prefix "J" indicates that it...

0 + ( A 1 × T ) + ( A 2 × T 2 ) {\displaystyle A=A_{0}+(A_{1}\times T)+(A_{2}\times T^{2})} ; T in centuries (cy) is 36,525 days from epoch J2000.0....

once around the ecliptic. It equals 365.256363004 ephemeris days for the J2000.0 epoch. The sidereal year differs from the solar year, "the period of time...

AXP 1E 1048.1-5937 Observation data Epoch J2000.0      Equinox J2000.0 (ICRS) Constellation Carina Right ascension 10h 50m 08.93s Declination −59° 53′ 19...

duration is 365.256363004 days (365 d 6 h 9 min 9.76 s) (at the epoch J2000.0 = January 1, 2000, 12:00:00 TT). Today the mean tropical year is defined...

secularly and periodically. The quantities given are the values at the instant J2000.0 of the secular variation, ignoring all periodic variations. aphelion =...

or synodic month, is the period from one new moon to the next. At the J2000.0 epoch, the average length of a lunation is 29.53059 days (or 29 days, 12...

standard epoch is J2000.0, which is January 1, 2000 at 12:00 TT. The prefix "J" indicates that it is a Julian epoch. Prior to J2000.0, astronomers used...

commonly used are: Mean equinox of a standard epoch (usually J2000.0, but may include B1950.0, B1900.0, etc.) is a fixed standard direction, allowing positions...