Telescopes & Astronomy

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Cassegrain Telescope

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  1. ZWO 2 inch Sulfur II (SII) filter 7nm
    AUD $399.00

    In Stock

  2. ZWO 2 inch Oxygen III (OIII) filter 7nm
    AUD $399.00

    In Stock

    The ZWO 7nm OIII filter is centered around the Oxygen III band of 501nm. Oxygen III or double ionised oxygen occurs at  primarily at 500.7nm and secondarily 495.9nm.  The highest levels of OIII are usually found in diffuse and planetary nebulae. The OIII emission lines were first discovered in the 1860s in spectra of planetary nebulae.  OIII wavelengths relate to the green-turquoise-cyan in colour on the spectrum whilst the narrowband width makes the background space very black.

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