DayStar Sodium Na D-line Filters - University
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.
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.
* 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.
DayStar Product Number: SNAD-UNV
Until recently, these specialty filters were the domain of scientists only. Since each DayStar Sodium Na D-line Filter must be individually produced, they must be pre-ordered and a minimum of 6 months must be allowed to fulfill the order. Please contact our expert sales staff for further ordering information. Thank you!