Coordinated Lunar Time ɛntɛ nimdeɛ a wɔbisa — ɛtumi yɛ ɔka nnɛ yi de nimdeɛ a ɛka ne asɛm. Asɛm yi kyerɛ moontimenow.com ɔboɔ no asɛm ɔka nimdeɛ, J2000 ɛfiri to ɔboɔ no mfoɔ algorithm.
J2000.0 Reference Epoch
Asɛm pata no hia asɛm a ɛfiri. Ɔboɔ no asɛm yi mu, yoo de J2000.0 ɛfiri: 2000-01-01 12:00:00 UTC (anadwo). Eyi yɛ asɛm a ɛfiri a NASA, ESA, ne asɛm suakↄfo de.
J2000.0 = Julian Date 2451545.0। Nnɛ a ɛfiri J2000.0 ɛfiri no, yoo tumi aka sɛnea ɔboɔ no asɛm akaa asase asɛm.
Asɛm a Ɛkaa Nɔma
Ɔka a ɛhoɔ no yɛ asɛm. Relativistic asɛm a ɛkaa yɛ +56.02 microseconds wɔ asase nnɛ biako. Asɛm a ɛka no nyinaa::
1. Nnɛ a ɛfiri J2000.0 ɛfiri no (na kɛse nyɛ) 2. Yɔ 56.02 microseconds 3. De asɛm yi de UTC asɛm no
Abɔ asɛm mu, 2025-01-01 mu, ~9,131 nnɛ afi J2000.0 ɛfiri no. Asɛm a ɛkaa no = 9,131 × 56.02 = 511,418.62 microseconds, anan ~0.511 sekan।।
Asɛm a ɛkaa no de aduri sɛm a ɛka asase ne ɔboɔ no asɛm, na sɔ owia ak↔ asɛm a ɛka. NIST 2024 ak↔kↄ no de akakye asɛm abɔ no nyinaa.
ΔT — Asase K↔ Asɛm a Ɛka
Sɛ wɔkyɛ asɛm a ɛfiri asɛm a wɔtaa mu. Asɛm suakↄfo de Terrestrial Time (TT) ma, na yoo asɛm de UTC na leap sekan sɛ asase k↔ gyini.
TT-UTC a ɛka no kyɛ ΔT (Delta T). Nnɛ yi mu (2015–2035), ΔT yɛ ~69.36 sekan na ɛk↔ ware — ~−0.06 sekan/afe. Yoo asɛm yi de polynomial IERS data mu:
ΔT ≈ 69.36 − 0.06 × (afe − 2020)
Asɛm yi ma ɔboɔ no asɛm a ɛwɔ asɛm a ɛne UTC asɛm a ɛwɔ wo asetena so.
Ɔboɔ no Mfoɔ Asɛm — Meeus Algorithm
Ɔboɔ no mfoɔ asɛm de Jean Meeus algorithm fi Astronomical Algorithms (Chapter 49) de. Akↄkↄ yi ka asɛm a ɛwɔ ɔboɔ foforo, ɔboɔ foforo, ne ɔboɔ quarter asɛm de asɛm akↄ 25 fi ɔboɔ no owia ak↔ nimdeɛ.
Algorithm yi de lunation nɔma (k) ma nnɛ biako, na ɛde trigonometric asɛm a ɛka ɔboɔ no ɛmƒo asɛm, owia ɛmƒo asɛm, ɔboɔ no latitude argue, ne ascending node longitude.
Asɛm a ɛka foforɔ de ɔboɔ foforo (Table 49.a), ɔboɔ foforo (Table 49.b), ne ɔboɔ quarter (Table 49.c/d na W asɛm a ɛka). Ɛka no yɛ ~2 sekan USNO asɛm no.
Ɔhene ne Mfoɔ Din
Adwuma akɛse Mfoɔ mu, ɔboɔ no ɔhene de piecewise interpolation ɔboɔ quarter asɛm a ɛka a wɔaka so. Akↄkↄ yi fa ɔboɔ no owia k↔ asɛm a ɛkaa (perigee-k↔ bio, apogee-k↔ ware), na ɛka ɔhene asɛm a ɛka sɛ deɛ wɔ simple sinusoidal.
Mfoɔ din de lunation akↄ no fo: Ɔboɔ Foforo → Waxing Crescent → Ɔboɔ Quarter a Ɛdii → Waxing Gibbous → Ɔboɔ Foforo → Waning Gibbous → Ɔboɔ Quarter a Ɛakↄ → Waning Crescent। Mfoɔ akↄ de asɛm a ɛaka no pa, ɛntɛ kɛse asɛm no.