天體力學第10課星曆表1問題6：軌道根數

pang

天體力學第10課星曆表1問題6：軌道根數

太陽系天體的軌道根數分平均軌道根數和瞬時軌道根數兩種。

平均軌道根數袛適用於大行星，由此根數計算得的位置是平均位置，不是準確的瞬時位置，這根數可參見中國天文年曆。

瞬時軌道根數適用於大行星、小行星和彗星等，由它可得準確的瞬時位置。小行星的瞬時軌道根數可由網址 http://asteroid.lowell.edu/ 下載；大行星的瞬時軌道根數雖可由電腦安裝版中國天文年曆計算，但此程式會產生亂碼，不適合港澳台用戶，且其精度低及儲存檔案頗煩。

現懇請同好幫助尋找大行星和彗星的瞬時軌道根數電子版，如asteroid.lowell.edu般有高精度及容易儲存檔案。 謝謝！

彭祿勝  謹啟   2009-12-01

mca

JPL 有個即時天文年曆，

(介紹)
http://ssd.jpl.nasa.gov/?ephemerides

High precision ephemerides for solar-system bodies are available on-line using JPL's HORIZONS system. Most optical and radar observers will be best served by using our HORIZONS system to generate custom observer-table ephemerides. Our on-line HORIZONS system can also be used to output ephemerides in the form of osculating orbital elements and/or Cartesian vectors (position, velocity, and acceleration). However, there are some ephemeris data files available for export (see below) for those rare cases when HORIZONS will not suffice.

Professionals requiring high-precision ephemerides readable from their own software may find ephemeris data files (in SPK format) and a software toolkit needed to read those files from JPL's NAIF web-site. SPK files for planetary and planetary satellite ephemerides are available from NAIF. Comet and asteroid SPK files may be generated using our HORIZONS system.


(例子：  小行星 38960號 )
http://ssd.jpl.nasa.gov/horizons ... p=sb&sstr=38960


輸入用家的要求條件後，click "Generate Ephemeris" 便列出即時軌道數據。

AC

mca

IAU 亦列出最精密的 Ephemeris (used by professionals)

http://iau-comm4.jpl.nasa.gov/access2ephs.html

AC