added a masked array to Map
added a masked array to Map

sdss/marvin,albireox/marvin,sdss/marvin,sdss/marvin,bretthandrews/marvin,albireox/marvin,sdss/marvin,bretthandrews/marvin,bretthandrews/marvin,albireox/marvin,albireox/marvin,bretthandrews/marvin