*summary of function*

    **Key Arguments:**
        - ``exposure`` -- the atlas expsosure metadata
        - ``log`` -- logger

    **Return:**
        - None

    **Usage:**
        .. todo::

            add usage info
            create a sublime snippet for usage

        .. code-block:: python 

            usage code

def _match_single_exposure_against_pyephem_db(
        exposure,
        log):
    """*summary of function*

    **Key Arguments:**
        - ``exposure`` -- the atlas expsosure metadata
        - ``log`` -- logger

    **Return:**
        - None

    **Usage:**
        .. todo::

            add usage info
            create a sublime snippet for usage

        .. code-block:: python 

            usage code            
    """
    log.info('starting the ``_match_single_exposure_against_pyephem_db`` function')

    global tileSide
    global magLimit
    global DEG_TO_RAD_FACTOR
    global nside
    global moversDict

    matchedObjects = []
    expId = exposure["expname"]
    raFc = float(exposure["raDeg"])
    decFc = float(exposure["decDeg"])

    # GENERATE THE EXPOSURE HEALPIX ID MAP
    decCorners = (decFc - tileSide / 2,
                  decFc + tileSide / 2)
    corners = []
    for d in decCorners:
        if d > 90.:
            d = 180. - d
        elif d < -90.:
            d = -180 - d
        raCorners = (raFc - (tileSide / 2) / np.cos(d * DEG_TO_RAD_FACTOR),
                     raFc + (tileSide / 2) / np.cos(d * DEG_TO_RAD_FACTOR))
        for r in raCorners:
            if r > 360.:
                r = 720. - r
            elif r < 0.:
                r = 360. + r
            corners.append(hp.ang2vec(r, d, lonlat=True))

    # NEAR THE POLES RETURN SQUARE INTO TRIANGE - ALMOST DEGENERATE
    pole = False
    for d in decCorners:
        if d > 87.0 or d < -87.0:
            pole = True

    if pole == True:
        corners = corners[1:]
    else:
        # FLIP CORNERS 3 & 4 SO HEALPY UNDERSTANDS POLYGON SHAPE
        corners = [corners[0], corners[1],
                   corners[3], corners[2]]

    # RETURN HEALPIXELS IN EXPOSURE AREA
    expPixels = hp.query_polygon(nside, np.array(
        corners))

    # MATCH HEALPIX ON EXPOSURE AGAINST PYEPHEM DATABASE
    for ele in expPixels:
        if ele in moversDict:
            for o in moversDict[ele]:
                d2 = copy.deepcopy(o)
                d2["expname"] = expId
                matchedObjects.append(d2)

    log.info('completed the ``_match_single_exposure_against_pyephem_db`` function')
    return matchedObjects