sdss_finder.py

import os 

#Object catalog
from astroquery.simbad import Simbad

#Coordinates and astornomical units
from astropy import units as u
from astropy.coordinates import SkyCoord 
import astropy.coordinates as coord

#Url stuff
from urllib.parse import urlencode
from urllib.request import urlretrieve

class SDSS:
    def get_SDDS_image(self, coords_deg_lst, chat_id):
        #Turn RA & DEC strings into floats.
        ra = float(coords_deg_lst[0])
        dec = float(coords_deg_lst[1])
        #Calculate the center of the file to be retrieved.
        hcg7_center = SkyCoord(ra*u.deg, dec*u.deg, frame='icrs')
        type(hcg7_center.ra), type(hcg7_center.dec)
        #Size in pixels of image to be downloaded.
        impix_w = 1657
        impix_h = 1129
        #Frame width in degrees.
        imsize = 1.2*u.deg
        #Base url to queery for SDSS cutouts
        cutoutbaseurl = 'http://skyservice.pha.jhu.edu/DR12/ImgCutout/getjpeg.aspx'
        #Queery to concatenate to base url
        query_string = urlencode(dict(ra=hcg7_center.ra.deg, 
                                        dec=hcg7_center.dec.deg, 
                                        width=impix_w, height=impix_h, 
                                        scale=imsize.to(u.arcsec).value/impix_w))
        #
        url = cutoutbaseurl + '?' + query_string
        #Download .jpg file
        urlretrieve(url, 'SDSS_' + str(chat_id) + '.jpg')

    #Convert 'hh:mm:ss hh:mm:ss' coords to deg
    def convert_to_deg(self, obj_ra, obj_dec):
        #Generate skycoord object with RA & DEC
        coords_deg = SkyCoord(str(obj_ra + " " + obj_dec), unit=(u.hourangle, u.deg))
        #Extract RA & DEC from skycoord obj
        coords_deg_ra = round(coords_deg.ra.degree, 4)
        coords_deg_dec = round(coords_deg.dec.degree, 4)
        #Generate string with RA & DEC
        str_list = [str(coords_deg_ra), str(coords_deg_dec)]
        return str_list

    #Find object coordinates from "nickname" input.
    def find_object_coords_fname(self, object_name, chat_id):
        try:
            #Query Simbad for the object.
            result_table = Simbad.query_object(object_name)
            if result_table == None:
                self.object_at_string = None
                return True
            #Extract RA & DEC
            obj_ra = result_table['RA'][0].replace(" ", ":")
            obj_dec = result_table['DEC'][0].replace(" ", ":")
            #Generate coords string
            coords = ' '.join(self.convert_to_deg(obj_ra, obj_dec))
            #Get image for coords
            self.get_SDDS_image(self.convert_to_deg(obj_ra, obj_dec), chat_id)
            #Get constellation for coords
            constellation = coord.get_constellation(SkyCoord(coords, frame='icrs', unit=(u.deg)))
            #Generate string with RA, DEC, and constellation
            self.object_at_string = "Object <b>{}</b> is at:\n○ RA:  {} \n○ DEC:  {} \n \nIn the constellation of <b>{}</b>.".format(object_name.upper(), obj_ra, obj_dec, constellation)
            return False        
        
        except:
            return True

    def cleanup(self, chat_id):
        os.remove('SDSS_' + str(chat_id) + '.jpg')

    def get_SDDS(self, update, context, chat_id):
        object_name = update.message.text
        return [self.find_object_coords_fname(object_name, chat_id), self.object_at_string]