SpaceApps Challenge 2014. Calculate ephemerides given a set of Earth coordinates (Latitude, Longitude), time and altitude. The API accepts TLE data for satellites and xephem data for space bodies.

ephemcalc.py

from flask import Flask, jsonify, request
from datetime import tzinfo, timedelta, datetime

import json
import ephem

app = Flask(__name__)

@app.route("/spacebody")
def spacebody():
    ephem_line = str(request.args['xephem_line'])
    space_object = ephem.readdb(ephem_line)
    user = calculate_user(request)
    rising_transit_setting = calculate_rising_transit_setting(user, space_object)
    return jsonify(rising_transit_setting)

@app.route("/satellite")
def satellite():

    user = calculate_user(request)
    space_object = calculate_tle(request)
    try:
        rising_transit_setting = calculate_passing(user, space_object)
    except:
        rising_transit_setting = calculate_rising_transit_setting(user, space_object)
    
    return jsonify(rising_transit_setting)


def calculate_tle(request):
    tle0 = request.args['tle0']
    tle1 = request.args['tle1']
    tle2 = request.args['tle2']
    space_object = ephem.readtle(str(tle0), str(tle1), str(tle2))
    print space_object
    return space_object

def calculate_user(request):
    user = ephem.Observer()
    print user
    lat = request.args['lat']
    print lat
    print request.args.keys()
    lon = request.args['lon']
    if 'date' in request.args.keys():
        date = dateatetime.utcfromtimestamp(int(request.args['date']))
    else:
        date = datetime.datetime.now()
    if 'elevation' in request.args.keys():
        elevation = float(request.args['elevation'])
    else:
        elevation = 0.0
    user.lat, user.lon, user.date, user.elevation = str(lat), str(lon), str(date), elevation
    print user
    return user

def calculate_rising_transit_setting(user, space_object):

    space_object.compute(user)
    previous_rising, pr_az, pr_alt = user.previous_rising(space_object), space_object.az, space_object.alt
    next_rising, nr_az, nr_alt = user.next_rising(space_object), space_object.az, space_object.alt
    previous_transit, pt_az, pt_alt = user.previous_transit(space_object), space_object.az, space_object.alt
    next_transit, nt_az, nt_alt = user.next_transit(space_object), space_object.az, space_object.alt
    previous_setting, ps_az, ps_alt = user.next_setting(space_object), space_object.az, space_object.alt
    next_setting, ns_az, ns_alt = user.next_setting(space_object), space_object.az, space_object.alt
    rising_transit_setting = {
            'previous_rising': { 'date_time': previous_rising, 'az': pr_az, 'alt': pr_alt },
            'next_rising': { 'date_time': next_rising, 'az': nr_az, 'alt': nr_alt },
            'previous_transit': { 'date_time': previous_transit, 'az': pt_alt, 'alt': pt_az },
            'next_transit': {'date_time': next_transit, 'az': nt_az, 'alt': nt_alt},
            'previous_setting': { 'date_time': previous_setting,'az': ps_az, 'alt': ps_alt },
            'next_setting': { 'date_time': next_setting, 'az': ns_az, 'alt': ns_alt }
        }
    return rising_transit_setting

def calculate_passing(user, space_object):
    space_object.compute(user)
    print user
    passing = user.next_pass(space_object)
    print passing
    passing_dict = {
        'sublat': space_object.sublat, 
        'sublong': space_object.sublong, 
        'rise': { 'date_time': passing[0], 'az': passing[1] },
        'transit': {'date_time': passing[2], 'alt': passing[3] },
        'set': { 'date_time': passing[4], 'az': passing[5] }
        }
    return passing_dict

if __name__ == "__main__":
    app.run(debug=True)