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Designations:
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NGC 7023, Caldwell 4, Iris Nebula
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Object Type:
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Constellation:
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Cepheus
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21 hr 02 min (2000.0)
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+68° 10 min (2000.0)
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6.8 (star)
7.7 (nebula) |
Size:
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10 X 8 arcminutes
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Distance:
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1300 light years
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Discoverer:
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William Herschel, 1794
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Like delicate cosmic petals, these clouds of interstellar dust and gas have
blossomed 1,300 light-years away in the fertile star fields of the constellation Cepheus. Sometimes called the
Iris Nebula and dutifully cataloged as NGC 7023, this is not the only nebula in the sky to evoke the imagery of
flowers. Still, the beautiful digital image shows off the Iris Nebula's range of colors and symmetries in
impressive detail. Within the Iris, dusty nebular material surrounds a massive, hot, young star in its
formative years. Central filaments of cosmic dust glow with a reddish photoluminesence as some dust grains
effectively convert the star's invisible ultraviolet radiation to visible red light. Yet the dominant color
of the nebula is blue, characteristic of dust grains reflecting starlight. Dark, obscuring clouds of dust and
cold molecular gas are also present and can lead the eye to see other convoluted and fantastic shapes.
Infrared observations indicate that this nebula may contain complex carbon molecules known as PAHs. As shown
here, the Iris Nebula is about 6 light-years across.
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Telescope:
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Focal Length:
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1200 mm
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Mount:
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Camera
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SBIG ST10XME and SBIG AO-8 Adaptive Optics
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Guider:
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SBIG Remote Guide Head
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Exposures:
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24 8-minute, 10 90-second and 10 60-second Luminance exposures. The short exposures were used to repair the camera blooms from the longer exposures.
For the color, 5 8-minute and 10 45-second exposures were used for each of the three colors (R,G,B)
Total Exposure Time: 6 hours |
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Location:
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Cicero, IN
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Software:
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CCDSoft for image acquisition, processed with CCDStack and Photoshop CS2
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