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RE: Astronomical Imaging - Planetary Nebula
@terrylovejoy
I didn't "get" the Spirograph nebula's image with diffraction grating. Is this a single exposure with multiple images of the same object? Or different exposures put together? Thanks!
@hrj . This was a single exposure. I hope the attached image helps clarify what you are looking at. A star shows a continuous rainbow spectrum because its light is fairly distributed over the entire visible spectrum whereas the planetary nebula shines in distinct points in the spectrum due to excitation of electrons in elements such as Hydrogen and Oxygen.
@terrylovejoy Ah yes.. I understand it better now. The circular shapes in the spectograph had confused me, but now I see that the shape is co-incidental, and not a super-imposed image of the nebula itself.
Thank you!