  Observations of astronomical objects in the far ultraviolet (FUV wavelengths
span 900-1800{\AA}) from earth's orbit has been impeded due to bright
Lyman-{\alpha} geocoronal emission. The Johns Hopkins Rocket Group is
developing a hydrogen absorption cell that would act as a narrow band
Lyman-{\alpha} rejection filter to enable space-based photometric observation
in bandpasses that span over the Lyman ultraviolet region shortward of the
geocoronal line. While this technology has been applied to various planetary
missions with single element photomultiplier detectors it has yet to be used on
near earth orbiting satellites with a multi-element detector. We are working to
develop a cell that could be easily incorporated into future Lyman ultraviolet
missions. The prototype cell is a low-pressure (~ few torr) chamber sealed
between a pair of MgF2 windows allowing transmission down to 1150 {\AA}. It is
filled with molecular hydrogen that is converted to its neutral atomic form in
the presence of a hot tungsten filament, which allows for the absorption of the
Lyman-{\alpha} photons. Molecular hydrogen is stored in a fully saturated
non-evaporable getter module (St707TM), which allows the cell pressure to be
increased under a modest application of heat (a 20 degree rise from room
temperature has produced a rise in pressure from 0.6 to 10 torr). Testing is
now underway using a vacuum ultraviolet monochromator to characterize the cell
optical depth to Lyman-{\alpha} photons as functions of pressure and tungsten
filament current. We will present these results, along with a discussion of
enabled science in broadband photometric applications.
