PyEphem基本功能介绍

PyEphem为Python下的一个程序包， 用来进行天文历算， 虽然是爱好者编写的， 但是由于使用VOS87行星运动数据， 计算精度达到了很高的精度， 足以满足一般的观测需要。 详情参见 http://rhodesmill.org/pyephem/ 本文是学习该程序包的读书笔记。

火星在2018年的星座

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import ephem
m = ephem.Mars('2018')
print(ephem.constellation(m))
('Lib', 'Libra')

计算不同天体在1970年1月1日0时的位置等信息

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from ephem import *
mars = Mars('1970') # 火星
print('%s, %s, %.10f' % (mars.name, mars.elong, mars.size))

sun = Sun('1970') # 太阳
print('%s, %s, %.10f' % (sun.name, sun.elong, sun.size))

moon = Moon('1970') # 月亮
print('%s, %s, %.10f' % (moon.name, moon.elong, moon.size))

mercury = Mercury('1970') # 水星
print('%s, %s, %.10f' % (mercury.name, mercury.elong, mercury.size))

venus = Venus('1970') # 金星
print('%s, %s, %.10f' % (venus.name, venus.elong, venus.size))

jupiter = Jupiter('1970') # 木星
print('%s, %s, %.10f' % (jupiter.name, jupiter.elong, jupiter.size))

saturn = Saturn('1970') # 土星
print('%s, %s, %.10f' % (saturn.name, saturn.elong, saturn.size))

uranus = Uranus('1970') # 天王星
print('%s, %s, %.10f' % (uranus.name, uranus.elong, uranus.size))

neptune = Neptune('1970') # 海王星
print('%s, %s, %.10f' % (neptune.name, neptune.elong, neptune.size))

pluto = Pluto('1970') # 冥王星
print('%s, %s , %.10f' % (pluto.name, pluto.elong, pluto.size))
Mars, 62:04:48.0, 5.9295825958
Sun, 0:00:00.0, 1951.8359375000
Moon, -89:27:48.3, 1831.0117187500
Mercury, 18:52:17.4, 7.5804867744
Venus, -5:42:32.4, 9.9605798721
Jupiter, -67:50:24.1, 34.2474060059
Saturn, 111:52:32.6, 18.8122367859
Uranus, -91:26:29.1, 3.8586533070
Neptune, -40:17:59.5, 2.1982953548
Pluto, -102:16:48.8 , 0.2606950402
### a_ra — Astrometric geocentric right ascension for the epoch specified
### a_dec — Astrometric geocentric declination for the epoch specified
### g_ra and ra — Apparent geocentric right ascension for the epoch-of-date
### g_dec and dec — Apparent geocentric declination for the epoch-of-date
### elong — Elongation (angle to sun)
### mag — Magnitude
### size — Size (diameter in arcseconds)
### radius — Size (radius as an angle)
### circumpolar — whether it stays above the horizon
### neverup — whether is stays below the horizon
############################################ 
hlon — Heliocentric longitude (see next paragraph)
### hlat — Heliocentric latitude (see next paragraph)
### sun_distance — Distance to Sun (AU)
### earth_distance — Distance to Earth (AU)
### phase — Percent of surface illuminated

已知观测者的位置， 包括 经纬度和海拔， 观测日期和时刻， 求天体的高度和方位

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gatech = Observer()
gatech.lon = '114.169576'
gatech.lat = '22.451939'
gatech.elevation = 5
gatech.date = '2014/9/22 22:30:00'
v = Venus(gatech)
print('%s, %s' % (v.alt, v.az))
11:47:49.3, 89:41:14.6

已知彗星的根数， 计算彗星的亮度和位置， 读取的格式为 xephem格式

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line = "C/2002 Y1 (Juels-Holvorcem),e,103.7816,166.2194,128.8232,242.5695,
0.0002609,0.99705756,0.0000,04/13.2508/2003,2000,g  6.5,4.0"
yh = ephem.readdb(line)
yh.compute('2007/10/1')
print('%.10f' % yh.earth_distance)
print(yh.mag)
14.8046731949
23.96
## 已知人造卫星的轨道根数， 计算其在任意时刻的高度和方位
### 读取 xephem格式用 readdb 方法
### 写出 xepheme格式， 用 writedb 方法
######### 人造卫星为 tle格式, 这里用readtle方法来阅读
line1 = "ISS (ZARYA)"
line2 = "1 25544U 98067A   03097.78853147  .00021906  00000-0  28403-3 0  8652"
line3 = "2 25544  51.6361  13.7980 0004256  35.6671  59.2566 15.58778559250029"
iss = ephem.readtle(line1, line2, line3)
iss.compute('2003/3/23')
print('%s %s' % (iss.sublong, iss.sublat))
-76:24:18.3 13:05:31.1
('Sgr', 'Sagittarius')
50.54
V2 - P274
V2 - P135
V1 - P273

计算月亮在某时刻所在星座

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m = Moon('1980/6/1')
print(constellation(m))
('Sgr', 'Sagittarius')

查询某一赤经赤纬在不同星图中的页码

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####### Uranometria by Johannes Bayer.
####### Uranometria 2000.0 edited by Wil Tirion.
#######  Millennium Star Atlas by Roger W. Sinnott and Michael A. C. Perryman.

ra, dec = '7:16:00', '-6:17:00'print(ephem.uranometria(ra, dec))

print(ephem.uranometria2000(ra, dec))

print(ephem.millennium_atlas(ra, dec))

转换儒略日

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ephem.julian_date('2000/1/1')

计算 Delta T

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print(ephem.delta_t('1980'))

计算两个物件的角距

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m1 = ephem.Moon('1970/1/16')
m2 = ephem.Moon('1970/1/17')
s = ephem.separation(m1, m2)
print("In one day the Moon moved %s" % s)
In one day the Moon moved 12:33:28.5

坐标系转换

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np = Equatorial('0', '90', epoch='2000')
g = Galactic(np)
print('%s %s' % (g.lon, g.lat))
####   Equatorial
####   ra — right ascension
####   dec — declination
####   epoch — epoch of the coordinate
####   Ecliptic
####   lon — ecliptic longitude (+E)
####   lat — ecliptic latitude (+N)
####   epoch — epoch of the coordinate
####   Galactic
####   lon — galactic longitude (+E)
####   lat — galactic latitude (+N)
####   epoch — epoch of the coordinate
122:55:54.9 27:07:41.7

计算某地点的天象

天体的高度和方位

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#### Describes a position on Earth’s surface.lowell = ephem.Observer()
lowell.lon = '-111:32.1'
lowell.lat = '35:05.8'
lowell.elevation = 2198
lowell.date = '1986/3/13'
j = ephem.Jupiter()
j.compute(lowell)
print('%s %s' % (j.alt, j.az))
##  Attributes can be set:
##      date — Date and time
##      epoch — Epoch for astrometric RA/dec
##      lat — Latitude (+N)
##      lon — Longitude (+E)
##      elevation — Elevation (m)
##      temp — Temperature (°C)
##      pressure — Atmospheric pressure (mBar)
##  ##      The date defaults to now().
##      The epoch defaults to '2000'.
##      The temp defaults to 25°C.
##      The pressure defaults to 1010mBar.
##      Other attributes default to zero.
0:57:44.7 256:41:01.3

天体的升降与中天时刻

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############## 内置的城市位置数据
city = city('Beijing')
print('%s %s' % (city.lat, city.lon))
############# 天体的升降和中天
sitka = Observer()
sitka.date = '1999/6/27'
sitka.lat = '57:10'
sitka.lon = '-135:15'm = Mars()
print(sitka.next_transit(m))
print('%s %s' % (m.alt, m.az))
print(sitka.next_rising(m, start='1999/6/28'))
print('%s %s' % (m.alt, m.az))
#### 给定观测者之后， 每个天体可以使用方法 （人造卫星除外）
### previous_transit()
### next_transit()
### previous_antitransit()
### next_antitransit()
### previous_rising()
### next_rising()
### previous_setting()
### next_setting()
39:54:15.2 116:24:26.7
1999/6/27 04:22:45
21:18:33.6 180:00:00.0
1999/6/28 23:28:25
-0:00:05.8 111:10:41.6

人造卫星升落和中天时刻等

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##### 某年某月某日， 某地， 计算人造卫星掠过的时刻
line1 = "IRIDIUM 80 [+]"
line2 = "1 25469U 98051C   09119.61415140 -.00000218  00000-0 -84793-4 0  4781"
line3 = "2 25469  86.4029 183.4052 0002522  86.7221 273.4294 14.34215064557061"
iridium_80 = ephem.readtle(line1, line2, line3)

city.date = '2009/5/1'
info = city.next_pass(iridium_80)
print("Rise time: %s azimuth: %s" % (info[0], info[1]))
####  返回值的时刻####  
0  Rise time####  
1  Rise azimuth####  
2  Transit time####  
3  Transit altitude####  
4  Set time####  
5  Set azimuth
##############################################
Rise time: 2009/5/1 00:45:05 azimuth: 6:13:37.5

计算日出时刻

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sun = Sun()
greenwich = Observer()
greenwich.lat = '51:28:38'
print(greenwich.horizon)
greenwich.date = '2007/10/1'
r1 = greenwich.next_rising(sun)
greenwich.pressure = 0
greenwich.horizon = '-0:34'
greenwich.date = '2007/10/1'
r2 = greenwich.next_rising(sun)
print('Visual sunrise: %s' % r1)
print('Naval Observatory sunrise: %s' % r2)
0:00:00.0
Visual sunrise: 2007/10/1 05:59:30
Naval Observatory sunrise: 2007/10/1 05:59:50

恒星时

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madrid = ephem.city('Madrid')
madrid.date = '1978/10/3 11:32'
print(madrid.sidereal_time())
12:04:28.09
2000/3/20 07:35:17
2000/6/21 01:47:51
Spring lasted 92.8 days

春分， 秋分， 冬至， 夏至的时刻

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d1 = ephem.next_equinox('2000')
print(d1)
d2 = ephem.next_solstice(d1)
print(d2)
t = d2 - d1
print("Spring lasted %.1f days" % t)
#### 相应的方法
#### previous_solstice()
#### next_solstice()
######## previous_equinox()
#### next_equinox()
######## previous_vernal_equinox()
#### next_vernal_equinox()

月相

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d1 = ephem.next_full_moon('1984')
print(d1)

d2 = ephem.next_new_moon(d1)
print(d2)
### 朔
### previous_new_moon()
### next_new_moon()
### 上弦月
### previous_first_quarter_moon()
### next_first_quarter_moon()
### 望
### previous_full_moon()
### next_full_moon()
### 下弦月
### previous_last_quarter_moon()
### next_last_quarter_moon()
1984/1/18 14:05:10
1984/2/1 23:46:25

角度转换

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a = ephem.degrees('180:00:00')
print(a)
a
print("180° is %f radians" % a)
h = ephem.hours('1:00:00')
deg = ephem.degrees(h)
print("1h right ascension = %s°" % deg)
## 时间和角度输入
ephem.degrees(ephem.pi / 32)
ephem.degrees('5.625')
ephem.degrees('5:37.5')
ephem.degrees('5:37:30')
ephem.degrees('5:37:30.0')
ephem.hours('0.375')
ephem.hours('0:22.5')
ephem.hours('0:22:30')
ephem.hours('0:22:30.0')
180:00:00.0
180° is 3.141593 radians
1h right ascension = 15:00:00.0°
#### 日期时间的输入d = ephem.Date('1997/3/9 5:13')
print(d)
d
d.triple()
d.tuple()
d + ephem.hour
print(ephem.date(d + ephem.hour))
print(ephem.date(d + 1))
### 输入日期的格式ephem.Date(35497.7197916667)
ephem.Date('1997/3/10.2197916667')
ephem.Date('1997/3/10 05.275')
ephem.Date('1997/3/10 05:16.5')
ephem.Date('1997/3/10 05:16:30')
ephem.Date('1997/3/10 05:16:30.0')
ephem.Date((1997, 3, 10.2197916667))
ephem.Date((1997, 3, 10, 5, 16, 30.0))
1997/3/9 05:13:00
1997/3/9 06:13:00
1997/3/10 05:13:00
35497.71979166667

亮星列表

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rigel = ephem.star('Rigel')
print('%s %s' % (rigel._ra, rigel._dec))
5:14:32.30 -8:12:06.0

城市列表

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stuttgart = ephem.city('Stuttgart')
print(stuttgart)
print(stuttgart.lon)
<ephem.Observer date='2018/8/27 05:17:01' 
epoch='2000/1/1 12:00:00' 
lon='9:10:50.8' 
lat='48:46:37.6' 
elevation=249.205185m 
horizon=0:00:00.0 
temp=15.0C 
pressure=983.6685758505818mBar>
9:10:50.8

天文常量

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#### PyEphem provides constants for the dates of a few major star-atlas epochs:
#### 不同历元#  B1900# B1950# J2000
### PyEphem provides, for reference, the length of four distances, all in meters:

### 天文常量print(ephem.meters_per_au)
print(ephem.earth_radius)
print(ephem.moon_radius)
print(ephem.sun_radius)
#### PyEphem provides the speed of light in meters per second:
## 光速 m/sprint(ephem.c)
149597870000.0
6378160.0
1740000.0
695000000.0
299792458.0