The Iris Nebula (NGC 7023) by Barrington Russell

Camera by Barrington Russell @baz_astra Source: Date: 2022, October, 24 Author’s description: “The Iris Nebula (NGC 7023) is a grand reflection nebula in the constellation Cepheus - illuminated by the embedded star SAO 19158 and casting a trademark blue glow on the surrounding material as dust grains reflect the starlight. More detail: This nebula is of particular interest to scientists because of its colors. Reflection nebulae glow because they are made up of extremely tiny particles of solid matter, up to 10 or even 100 times smaller than dust particles on Earth. These particles diffuse the light around them, giving the nebula a second-hand glow that’s typically bluish (like our sky). While the Iris Nebula appears predominantly blue, the surrounding region includes large filaments of deep red, since some dust grains effectively convert the star’s invisible ultraviolet radiation to visible red light. Studying nebulae like this one helps astronomers learn more about the ingredients that combine to make stars. It took about a month to collect enough data to make the image; an endeavour largely beset by clouds and the full moon - along with losing (and then finding) some critical calibration frames! Two cameras were used; one highly-sensitive chilled monochrome unit to capture brightness information, and another more general-purpose colour camera for the RGB data. The image is, in astronomical parlance, a ’broadband’ image. This is a fancy way of saying that the light was captured from across the entire visible spectrum, and so the photograph colours are true-to-life. If your eyes were bigger, this is exactly what they’d see. Letting a sensitive camera look unfiltered for a long time at such objects from a dark site introduces a secondary problem. The ultraviolet and infrared light being emitted by the stars quickly overwhelms the sensor, producing blooming and light leaks that otherwise swap the picture. To ameliorate this situation, I used a luminance filter - essentially a fancy piece of glass that blocks just those wavelengths, leaving only pure visible starlight for the camera to collect. Personally I *much* prefer these true-colour broadband images compared to the admittedly more colourful narrowband spectroscopic versions, since they give a better depiction of space more closely aligned with what we see with our eyes.“ Technical Details: Spectral Palette: L RGB Luminance RGB TOTAL INTEGRATION = 13 hrs Sky type: Bortle 2 ( mag./arc sec2) Location: Lolland, Denmark Cameras: ZWO ASI 1600MM Pro 294MC Pro Mount: Skywatcher HEQ5 Pro Telescope: Redcat 51 Filter: Astronomik L-2 UV/IR Cut Guiding: ZWO ASIAIR Software: APP Photoshop Music by Andrey Klimkovsky @AndreyKlimkovsky Track «Waves of evolution» Bandcamp: NEANE Records: Video editing by pictuREflection @pictuREflection #astrophotography #astronomy #NGC7023 #IrisNebula #Iris #Nebula #Cepheus #BarringtonRussell #AndreyKlimkovsky #DeepSky #music #ambient