# 恒星时

## 维基百科，自由的百科全书

• 一颗恒星的时角${\displaystyle \tau }$、它的赤经α和当地的恒星时θ之间的关系为${\displaystyle \tau =\theta -\alpha }$
• 当地的恒星时等于位于天顶的恒星的赤经
• 当地的恒星时等于正位于中天恒星的赤经

## 恒星时与太阳时

${\displaystyle 24^{h}\;(T_{s})=23^{h}56^{m}04^{s}.090\,53\;(T_{\odot })=(1-\upsilon )\times 24^{h}\;(T_{\odot })}$

${\displaystyle 24^{h}\;(T_{\odot })=24^{h}03^{m}56^{s}.555\,37\;(T_{s})=(1+\mu )\times 24^{h}\;(T_{s})}$

## 如何计算恒星时

${\displaystyle UT=LT-TZ}$

${\displaystyle JD=\left[365.25Y\right]+\left[{\frac {Y}{400))\right]-\left[{\frac {Y}{100))\right]+\left[30.59(M-2)\right]+D+1721088.5+{\frac {h}{24))+{\frac {m}{1440))+{\frac {s}{86400))\!}$

[]表示高斯符号，只取整数部分。

${\displaystyle MJD=JD-2400000.5}$

{\displaystyle {\begin{aligned}TJD&=JD-2440000.5\\&=MJD-40000\\\end{aligned))}

${\displaystyle {\bar {\theta ))_{G}=24^{h}\times (0.671262+1.0027379094\times TJD)\!}$
${\displaystyle {\bar {\theta ))_{G}=241.654320^{o}+360.9856473840^{o}\times TJD\!}$
• 注意: 本恒星时公式的基准日为 2440000.5 JD 不是简化儒略日 (MJD) 的简化基准日 2400000.5 JD, 两者差了 40000 天!!!
• 本公式最早版本是对的, 中间有网友把常数改错了, 还把 TJD 改成 MJD. 慎勿再错.
• 用 2440000.5 写的程式已经验证 (since 1980s). 编写程式时不要错打数字.

${\displaystyle {\bar {\theta ))={\bar {\theta ))_{G}+{\frac {\lambda }{15))\!}$ (hours), 或者
${\displaystyle {\bar {\theta ))={\bar {\theta ))_{G}+\lambda \!}$ (degrees).

## 外部链接

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