Terrestrial Dynamical Time
zamân-e tavânik-e zamini
Fr.: temps dynamique terrestre
A uniform atomic time scale for apparent geocentric ephemerides defined by a 1979 IAU resolution, which replaced Ephemeris Time. TDT is independent of the variable rotation of the Earth, and the length of the tropical year is defined in days of 86,400 seconds of international atomic time. In 1991 it was replaced by Terrestrial Time.
Fr.: temps terrestre
The modern astronomical standard for the passage of time on the surface of the Earth. It is the → coordinate time scale consistent with the theory of general relativity for an observer on the surface of the Earth. TT was renamed from Terrestrial Dynamical Time (TDT) in 1991. The fundamental unit of TT is the day of 86,400 SI seconds. It is related to the International Atomic Time by the relation: TDT = TAI + 32.184 sec.
Fr.: temps de test
That part of the working time of a telescope devoted to tests of coupled instruments or the telescope itself.
zamân (#), gâh (#), vaqt (vaxt) (#), tâmen
1) A non-spatial sequential relation in which events occur in apparently irreversible
succession from the past through the present to the future.
→ time's arrow.
M.E.; O.E. tima "limited space of time," from P.Gmc. *timon "time" (cf. O.N. timi "time," Swed. timme "an hour"), akin to L. tempus (genitive temporis) "time" (Fr. temps, Sp. tiempo, It. tempo); maybe related to Pers. Tabari tum, tomon, temen "time;" Aftari ton "time."
Zamân "time," from Mid.Pers. zamân, jamân "time," zamânak
loaned into Aramaic and Ar.,
loaned into Arm. žam, žamanak "time;"
prefixed Sogdian nγm "time, moment, hour;"
Proto-Iranian *gām- "to go, to come;"
cf. Av. gam- "to come; to go," jamaiti "goes;"
O.Pers. gam- "to come; to go;" Mod./Mid.Pers. gâm
"step, pace," âmadan "to come;" cf. Skt. gamati "goes;"
Gk. bainein "to go, walk, step;" L. venire "to come;"
Tocharian A käm- "to come;" O.H.G. queman "to come;" E. come;
PIE base *gwem- "to go, come."
tesk-e zamân, ~ vaqt
Fr.: attribution de temps de télescope
The assignment of telescope time by an expert panel to proposals after evaluating the merits of the observation projects.
Fr.: constante de temps
Th speed of response of a detector, usually measured as 1/(2πν), where ν is the chopping frequency at which the responsivity fails to 1/√2 of its maximum value.
time delay distance
apest-e derang-e zamâni
A distance-like quantity derived from → gravitational lensing time delay. It is given by a combination of three angular diameter distances in a strong lens system: DΔt = (1 + zL)[DA(EL)DA(ES) / DA(LS)], where zL is the → redshift of the → gravitational lens, while DA(EL), DA(ES), and DA(LS) are the angular diameter distances from the Earth to the lens, from the Earth to the source, and from the lens to the source, respectively. As each of the distance is proportional to the inverse of H0, DΔt is proportional to 1/H0.
Fr.: dilatation du temps
A phenomenon related to special and general relativity.
time of periapsis passage
zamân-e gozar az pirâhabâk
Fr.: temps de passage au périapse
Fr.: résolution temporelle
Same → temporal resolution.
Fr.: renversement du temps
A transformation operating on time in the equations of motion of a dynamical system in which t is replaced by -t.
Fr.: échelle de temps
A measure of duration of a specific process, such as → crossing time, → dynamical time scale, → evolutionary time scale, → Kelvin-Helmholtz time scale, → nuclear time scale, → photon escape time, → relaxation time, → star formation time scale.
Fr.: série temporelle
zonâr-e zamân, zamân-zonâr
Fr.: fuseau horaire
Any of the 24 zones on the Earth surface delimited by → meridians at approximately 15° intervals. In each time zone a common standard time is used, and the time is one hour earlier than the zone immediately to the east.
Fr.: flèche du temps
The sequence of all natural processes in which the → entropy increases. In other words, the fact that these processes all move in one direction in time and are → irreversible. The past is distinctly different from the future; things always grow older, never younger.
Fr.: genre temps
Fr.: intervalle genre temps
Fr.: appareil horaire
Any mechanical, electric, or electronic device, such as a clock or watch, designed to measure and display the passage of time.
Zamân-šomâr, literally "time counter," from zamân, → time, + šomâr "counter," from šomârdan "to count," from Mid.Pers. ôšmârtan, ôšmurtan "to reckon, calculate, enumerate, account for," from Av. base (š)mar- "to have in mind, remember, recall," pati-šmar- "to recall; to long for," hišmar-, cf. Skt. smar- "to remember, become aware," smarati "he remembers," L. memor, memoria, Gk. mermera "care," merimna "anxious thought, sorrow," martyr "witness."
Fr.: temps de passage
The time interval between the release of an electron at the photocathode and the arrival of an electron at the anode. Transit time is not a single-valued quantity, but has a bell-shaped distribution.