fixed issue #273
fixed issue #273

NMGRL/pychron,USGSDenverPychron/pychron,NMGRL/pychron,NMGRL/pychron,UManPychron/pychron,UManPychron/pychron,USGSDenverPychron/pychron,USGSDenverPychron/pychron,NMGRL/pychron,USGSDenverPychron/pychron,UManPychron/pychron,UManPychron/pychron