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DayStar is proud to offer Sodium Na- D line (5895.9Å )
filtering systems. For visual and photographic studies. Sodium filter
assemblies are designed for sub-angstrom observations with
single-cavity design. Sodium lines are very narrow, but very bright. A
very narrow filter of < 0.5Å is necessary to properly isolate the line from the continuum. The resulting image depicts high detail in granulation, supergranulation and P-modes.
Sodium
also shows impulsive-phase flare eruption kernels. Na D is a low
excitation line emitted when the low chromosphere is heated, usually at
footpoints of flux loops passing through a flare, as sodium D line
reflects the lower chromosphere. Visual and photographic images reveal
type image as Calcium, revealing granulation, but are much brighter and
more easily visible.
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Mount Wilson Solar Observatory
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University series filters are designed to operate unheated on the lower of the two Na D emission
lines; and can be heated to accomplish transmission on the higher of
the two Na D lines, making doppler studies possible by photographing in
each line and derriving difference images after subtracting an average
solar velocity image. This process is referred to as a dopplergram
velocity image, reveals the surface motions associated with
supergranulation.
These
filters have until now been primarily used for research purposes only,
performing doppler and supergranulation studies. Narrow bandpass Na D
line filters have also been used in deep-sky observations of IO, but
with significantly larger apertures.
DayStar Sodium Filter assemblies
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0.4Å Single cavity Amateur T-Scanner filter system $4500.00
- suitable for visual or photographic observing
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0.4Å Single cavity University series filter system $7200.00
- suitible for photographic and visual observing
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* Note.
These systems require an energy rejection pre-filter and F/30 focal
ratio for onband operation. Standard yellow glass DayStar Energy
rejection filters provide sufficient off-band energy rejection, as do
dielectric 'hot mirror' coated pre-filters.
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