m33_hsc_field_sizes.ipynb

{
 "cells": [
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [],
   "source": [
    "import numpy as np\n",
    "\n",
    "from astropy import units as u\n",
    "from astropy.coordinates import SkyCoord, CartesianRepresentation,SphericalRepresentation\n",
    "from astropy.table import Table\n",
    "from astropy.io import fits\n",
    "\n",
    "first = lambda x:next(iter(x))\n",
    "\n",
    "%matplotlib inline\n",
    "from matplotlib import style, pyplot as plt\n",
    "from mpl_toolkits.mplot3d import Axes3D"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [],
   "source": [
    "m33 = SkyCoord.from_name('M33')\n",
    "m33 = SkyCoord(m33, distance=700*u.kpc)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {},
   "outputs": [],
   "source": [
    "n = 100000\n",
    "rad = 161*u.kpc  # assume halo radius is ~161 kpc\n",
    "xyz = (np.random.rand(3, n)*2-1)*rad\n",
    "rep = CartesianRepresentation(xyz).represent_as(SphericalRepresentation)\n",
    "rep = rep[rep.distance<rad]\n",
    "halo = SkyCoord(rep + m33.data)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {},
   "outputs": [],
   "source": [
    "def fraction_of_halo_in_field(field_center):\n",
    "    n_in_field = np.sum(halo.separation(field_center) < 90*u.arcmin)\n",
    "    return n_in_field/len(halo)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "0.01732772245177752"
      ]
     },
     "execution_count": 9,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "fraction_of_halo_in_field(SkyCoord(m33.ra, 25*u.deg))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "0.019212826322904965"
      ]
     },
     "execution_count": 10,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "fraction_of_halo_in_field(SkyCoord(m33.ra, 29*u.deg))"
   ]
  }
 ],
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