projects/Untitled5.ipynb

Hogg-Barycenter-astropy-crap.ipynb

Untitled5.ipynb

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      "cell_type": "code",
      "source": "import astropy.coordinates as coord\nimport astropy.table as at\nfrom astropy.time import Time\nimport astropy.units as u\nimport matplotlib as mpl\nimport matplotlib.pyplot as plt\n%matplotlib inline\nimport numpy as np",
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      "source": "c = coord.SkyCoord(\n    ra=15.424*u.deg, \n    dec=53.117*u.deg,\n    distance=17.235*u.pc,\n    pm_ra_cosdec=0.513*u.arcsecond/u.yr,\n    pm_dec=0.8134*u.arcsecond/u.yr,\n    radial_velocity=25.5235*u.km/u.s,\n    obstime=Time('J2015.5')\n)",
      "execution_count": 29,
      "outputs": []
    },
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      },
      "cell_type": "code",
      "source": "ts = c.obstime + np.arange(0, 10, 1/365) * u.year",
      "execution_count": 30,
      "outputs": []
    },
    {
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      "cell_type": "code",
      "source": "c.velocity",
      "execution_count": 40,
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        {
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          "execution_count": 40,
          "data": {
            "text/plain": "<CartesianDifferential (d_x, d_y, d_z) in km / s\n    (-47.62171267, 30.3404001, 60.30130237)>"
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      },
      "cell_type": "code",
      "source": "pos_at_ts = c.data.to_cartesian() + c.velocity.to_cartesian() * (ts - c.obstime)\n\n# Assume constant velocity:\nvel_at_ts = c.velocity + coord.CartesianDifferential(np.zeros((3, len(ts))) * u.km/u.s)",
      "execution_count": 42,
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    },
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      },
      "cell_type": "code",
      "source": "c_at_ts = coord.SkyCoord(pos_at_ts.with_differentials(vel_at_ts), \n                         obstime=ts)",
      "execution_count": 45,
      "outputs": []
    },
    {
      "metadata": {
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          "end_time": "2020-10-15T20:37:35.535019Z"
        },
        "trusted": true
      },
      "cell_type": "code",
      "source": "(c_at_ts[-1].radial_velocity - c_at_ts[0].radial_velocity).to(u.m/u.s)",
      "execution_count": 48,
      "outputs": [
        {
          "output_type": "execute_result",
          "execution_count": 48,
          "data": {
            "text/plain": "<Quantity 3.66202397 m / s>",
            "text/latex": "$3.662024 \\; \\mathrm{\\frac{m}{s}}$"
          },
          "metadata": {}
        }
      ]
    },
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      "execution_count": null,
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      "cell_type": "code",
      "source": "",
      "execution_count": null,
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