software_tools/lsst_class.py at main · LSST-TVSSC/software_tools · GitHub

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# -*- coding: utf-8 -*-
"""
Created on Fri Oct 26 21:53:46 2018

@author: rstreet
"""

from astropy import units as u
from astropy.coordinates import SkyCoord
from matplotlib.patches import Circle
import numpy as np

class LSSTFootprint:
    """Class describing the parameters of a single LSST field of view"""

    def __init__(self,ra_centre=None,dec_centre=None):
        self.ra = ra_centre
        self.dec = dec_centre
        self.radius = 3.5/2.0  # deg radius field of view
        self.coord = SkyCoord(ra_centre+' '+dec_centre, unit=(u.hourangle, u.deg))
        self.pixel_scale = 0.2 # arcsec

    def draw_footprint(self,ax):
        """Method to draw a WFIRST-WFI footprint on a pre-existing figure Axis,
        centered at the x, y coordinates given."""

        ax.add_patch( Circle((self.coord.ra.degree,
                              self.coord.dec.degree),
                              self.radius,
                              edgecolor='yellow',
                              facecolor='none', linewidth=5.0,
                              fill=False) )

        return ax

    def count_stars_in_footprint(self,coords):
        """Method to count the number of stars within this footprint,
        given a set of SkyCoords"""

        sep = self.coord.separation(coords)

        stars_in_field = np.where( sep.degree < self.radius )[0]

        print('Number of stars within the LSST footprint: '+\
                    str(len(stars_in_field)))