坐标缩减python

Question

如何计算观测者在特定日期和时间在某个站点（经度、纬度）的星星位置（ra、dec）？我需要计算中包含所有元素的完整坐标还原（恒星自行、大气压力和温度...）

我尝试使用 pyephem，但我不确定我能否完成。

import ephem

polaris = ephem.readdb("Polaris,f|M|F7,2:31:48.704,89:15:50.72,2.02,1")

polaris.compute('2016/3/1 16:22:56')

print polaris.a_ra 
print polaris.a_dec

我也尝试过astroplan，我认为我更接近解决方案，但仍然不知道如何在减少后获得坐标并添加自行。

import astropy.units as u
from astropy.coordinates import EarthLocation
from astropy.coordinates import SkyCoord
from pytz import timezone
from astroplan import Observer
from astropy.time import Time
from astroplan import FixedTarget
import numpy as np
import astropy.units as u
from astroplan.plots import plot_sky
from astroplan.plots import plot_parallactic
from astroplan.plots import plot_airmass
import matplotlib.pyplot as plt
from astroplan import FixedTarget


longitude = '21d33m20.4s'
latitude = '+43d08m24.6s'
elevation = 1150 * u.m
time = Time('2015-06-16 12:00:00')

location = EarthLocation.from_geodetic(longitude, latitude, elevation)

observer = Observer(name='Name',
               location=location,
               pressure=0.615 * u.bar,
               relative_humidity=0.11,
               temperature=0 * u.deg_C,
               timezone=timezone('Europe/Belgrade'),
               description="..")



coordinates = SkyCoord('2h31m48.704s', '89d15m50.72s', frame = 'icrs')
polaris = FixedTarget(name='Polaris', coord=coordinates)

plot_airmass(polaris, observer, time)

ax = plt.gca()
box = ax.get_position()
ax.set_position([box.x0, box.y0, box.width * 0.8, box.height * 0.8])

plt.legend(loc=1, bbox_to_anchor=(1.35, 1))
plt.show()

Answer 1

你可能想试试 Skyfield，它是 PyEphem 的继任者，已经接近 1.0。虽然 PyEphem 的底层库不存储自行，但如果要应用自行，则必须在输入期间移动所有星星，而 Skyfield 会根据存储在 Star 对象本身中的运动动态地执行此操作。您正在考虑的减少在 Skyfield 中看起来像这样：

from skyfield.api import load, Star
ts = load.timescale()
t = ts.utc(2016, 4, 16, 15, 30)
planets = load('de421.bsp')
earth = planets['earth']
boston = earth.topos(longitude_degrees=(21, 33, 20.4),
                     latitude_degrees=(+43, 8, 24.6))
barnard = Star(ra_hours=(17, 57, 48.49803),
               dec_degrees=(4, 41, 36.2072),
               ra_mas_per_year=-798.71,
               dec_mas_per_year=+10337.77,
               parallax_mas=545.4,
               radial_km_per_s=-110.6)
astrometric = boston.at(t).observe(barnard)
ra, dec, distance = astrometric.radec()
print(ra)
print(dec)
apparent = astrometric.apparent()
ra, dec, distance = apparent.radec()
print(ra)
print(dec)
alt, az, distance = apparent.altaz(temperature_C=25.0,
                                   pressure_mbar=1013.25)
print(alt)
print(az)

如果您有兴趣，可以在 http://rhodesmill.org/skyfield/ 获取更多文档！

坐标缩减python

Coordinates reduction python

python

astronomy

pyephem