星历计算

• pyephem
• Skyfield

from skyfield.api import load

planets = load('data/de421.bsp')
earth, mars = planets['earth'], planets['mars']

ts = load.timescale()
t = ts.now()
astrometric = earth.at(t).observe(mars)
ra, dec, distance = astrometric.radec()

print(ra)
print(dec)
print(distance)

01h 08m 58.49s
+07deg 36' 53.9"
0.705051 au

from skyfield.api import Topos

naoc = Topos('40.002 N', '116.38 E')

naocs = earth + naoc

astrometric = naocs.at(t).observe(mars)
alt, az, d = astrometric.apparent().altaz()

alt, az, d

(<Angle 24deg 44' 28.6">, <Angle 101deg 09' 31.2">, <Distance 0.705033 au>)

计算日升日落

from skyfield import almanac
from pytz import timezone

zone = timezone('Asia/Shanghai')

f = almanac.dark_twilight_day(planets, naoc)

t0 = ts.utc(2020, 12, 4)
t1 = ts.utc(2020, 12, 10)

t, y = almanac.find_discrete(t0, t1, f)

for ti, e in zip(t, y):
    tstr = str(ti.astimezone(zone))[:16]
    print(tstr, ' ', almanac.TWILIGHTS[e], 'starts')

2020-12-04 16:49   Civil twilight starts
2020-12-04 17:19   Nautical twilight starts
2020-12-04 17:53   Astronomical twilight starts
2020-12-04 18:25   Night starts
2020-12-05 05:44   Astronomical twilight starts
2020-12-05 06:16   Nautical twilight starts
2020-12-05 06:50   Civil twilight starts
2020-12-05 07:20   Day starts
2020-12-05 16:49   Civil twilight starts
2020-12-05 17:19   Nautical twilight starts
2020-12-05 17:53   Astronomical twilight starts
2020-12-05 18:25   Night starts
2020-12-06 05:45   Astronomical twilight starts
2020-12-06 06:17   Nautical twilight starts
2020-12-06 06:51   Civil twilight starts
2020-12-06 07:21   Day starts
2020-12-06 16:49   Civil twilight starts
2020-12-06 17:19   Nautical twilight starts
2020-12-06 17:53   Astronomical twilight starts
2020-12-06 18:25   Night starts
2020-12-07 05:45   Astronomical twilight starts
2020-12-07 06:18   Nautical twilight starts
2020-12-07 06:52   Civil twilight starts
2020-12-07 07:22   Day starts
2020-12-07 16:48   Civil twilight starts
2020-12-07 17:19   Nautical twilight starts
2020-12-07 17:53   Astronomical twilight starts
2020-12-07 18:25   Night starts
2020-12-08 05:46   Astronomical twilight starts
2020-12-08 06:19   Nautical twilight starts
2020-12-08 06:53   Civil twilight starts
2020-12-08 07:23   Day starts
2020-12-08 16:48   Civil twilight starts
2020-12-08 17:19   Nautical twilight starts
2020-12-08 17:53   Astronomical twilight starts
2020-12-08 18:26   Night starts
2020-12-09 05:47   Astronomical twilight starts
2020-12-09 06:20   Nautical twilight starts
2020-12-09 06:54   Civil twilight starts
2020-12-09 07:24   Day starts
2020-12-09 16:49   Civil twilight starts
2020-12-09 17:19   Nautical twilight starts
2020-12-09 17:53   Astronomical twilight starts
2020-12-09 18:26   Night starts
2020-12-10 05:48   Astronomical twilight starts
2020-12-10 06:21   Nautical twilight starts
2020-12-10 06:54   Civil twilight starts
2020-12-10 07:25   Day starts

t, y = almanac.find_discrete(t0, t1, almanac.sunrise_sunset(planets, naoc))

for ti, e in zip(t, y):
    tstr = str(ti.astimezone(zone))[:16]
    msg = "日落"
    if e:
        msg = "日升"
    print(tstr, ' ', msg)

2020-12-04 16:49   日落
2020-12-05 07:20   日升
2020-12-05 16:49   日落
2020-12-06 07:21   日升
2020-12-06 16:49   日落
2020-12-07 07:22   日升
2020-12-07 16:48   日落
2020-12-08 07:23   日升
2020-12-08 16:48   日落
2020-12-09 07:24   日升
2020-12-09 16:49   日落
2020-12-10 07:25   日升

节气

from skyfield import almanac_east_asia as almanac_ea

t0 = ts.utc(2020, 12, 15)
t1 = ts.utc(2021, 12, 15)
t, tm = almanac.find_discrete(t0, t1, almanac_ea.solar_terms(planets))

for tmi, ti in zip(tm, t):
    print(tmi, almanac_ea.SOLAR_TERMS_ZHS[tmi], ti.utc_iso(' '))

18 冬至 2020-12-21 10:02:20Z
19 小寒 2021-01-05 03:23:26Z
20 大寒 2021-01-19 20:39:52Z
21 立春 2021-02-03 14:58:48Z
22 雨水 2021-02-18 10:43:58Z
23 惊蛰 2021-03-05 08:53:41Z
0 春分 2021-03-20 09:37:29Z
1 清明 2021-04-04 13:35:06Z
2 谷雨 2021-04-19 20:33:24Z
3 立夏 2021-05-05 06:47:10Z
4 小满 2021-05-20 19:37:07Z
5 芒种 2021-06-05 10:52:06Z
6 夏至 2021-06-21 03:32:10Z
7 小暑 2021-07-06 21:05:29Z
8 大暑 2021-07-22 14:26:26Z
9 立秋 2021-08-07 06:53:59Z
10 处暑 2021-08-22 21:34:59Z
11 白露 2021-09-07 09:52:56Z
12 秋分 2021-09-22 19:21:06Z
13 寒露 2021-10-08 01:39:02Z
14 霜降 2021-10-23 04:51:10Z
15 立冬 2021-11-07 04:58:46Z
16 小雪 2021-11-22 02:33:44Z
17 大雪 2021-12-06 21:57:04Z

恒星视位置

from skyfield.api import Star

vega = Star(ra_hours=(18, 36, 56.3363), dec_degrees=(+38, 47, 01.280))

t = ts.now()
astrometric = naocs.at(t).observe(vega)
ra, dec, distance = astrometric.radec()
print(ra)
print(dec)

18h 36m 56.34s
+38deg 47' 01.3"

app = astrometric.apparent()

alt, az, distance = app.altaz()

print(alt.dstr())
print(az.dstr())
print(distance)

53deg 58' 06.1"
76deg 17' 15.8"
2.06265e+14 au