Transit Detection.ipynb

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   "source": [
    "# Detecting Transits with REBOUND\n",
    "The following code finds transits along the x-axis of a one planet system."
   ]
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   "cell_type": "code",
   "execution_count": 1,
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   "source": [
    "import rebound\n",
    "import math"
   ]
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   "source": [
    "sim = rebound.Simulation()\n",
    "sim.add(m=1)\n",
    "sim.add(a=1,e=0.1,omega=0.25)"
   ]
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     "text": [
      "6.07928466797\n",
      "12.3624627686\n",
      "18.6456561279\n",
      "24.9288342285\n",
      "31.2120275879\n"
     ]
    }
   ],
   "source": [
    "transittimes = []\n",
    "p = sim.particles\n",
    "while len(transittimes)<5:\n",
    "    y_old = p[1].y\n",
    "    t_old = sim.t\n",
    "    DT = 1. # check for transits every DT time units. DT must be shorter than one orbit\n",
    "    sim.integrate(sim.t+DT) \n",
    "    t_new = sim.t\n",
    "    if y_old*p[1].y<0. and p[1].x>0.:   # sign changed:\n",
    "        while math.fabs(p[1].y)>1e-5:   # bisect until prec of 1e-5 reached\n",
    "            if y_old*p[1].y<0.:\n",
    "                t_new = sim.t\n",
    "            else:\n",
    "                t_old = sim.t\n",
    "            sim.integrate( (t_new+t_old)/2.)\n",
    "        transittimes.append(sim.t)\n",
    "        print sim.t\n",
    "        sim.integrate(sim.t+0.01)       # integrate a little to be past the transit "
   ]
  }
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