import time
import calendar


def get_utc_timestamp(date_, time_):
    """
        return unix timestamp in utc
      "startdate": "20130813",
      "starttime": "10:53:44",
    """
    t = time.strptime("%s-%s" % (date_, time_), '%Y%m%d-%H:%M:%S')
    epoch = calendar.timegm(t)
    return epoch