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NGC 7023 (Iris Nebula; Caldwell 4; LBN 487; VDB 139) - Cluster associated with nebulosity in Cepheus

LRGB combination (Click for a larger view 1400 x 1400 px)

Details

NGC 7023 was observed 18 October 1794 by William Herschel.

It is located about 3.5 degrees south west of Beta Cephei (Alfirk). This is a wonderful example of a reflection nebula. Its unusual structure gave rise to the name, the Iris Nebula. The nebula is illuminated by light for a Mag 6.8 star (HD200775) in its center. The bright blue light seen here is due to light being reflected off dust particles that survived the star's birth.

Right Ascension 21 : 00.5 (h:m)
Declination +68 : 10 (deg:m)
Distance - (ly)
Visual Brightness 7 (mag)
Apparent Dimension 18'

Seeing: Pickering 8 rating - Good to Excellent
Optic(s): Celestron 11" Schmidt Cassegrain + Alan Gee II telecompressor @ f/6.3
Mount: CGE equatorial
Camera: Artemis Art 4021 - monochrome cooled CCD camera – 2048 x 2048 px ; 16x16 mm; 7.4 µm x 7.4 µm
Filters: Astronomics LRGB Set, SupaSlim TrueTechnology Computerized Filter Wheel
Dates/Times: 2011-08-31/ UT 01:03:17
Location: Rozhen Observatory, BG, longitude: E 24 44' 19", latitude: N 41 41' 51"
Exposure Details:

L = 40 min, R = 40 min, G = 40 min and B = 40 min (1x1 binning), Subexposures = 10 min, Total Exposure Time - 160 min

More details: Dark frames reduction
Guiding: Starlight Xpress Lodestar Autoguider on APO 90/600+barlow @ f/13.4
Processing:

PixInsight / PS

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All Contents copyright Velimir Popov unless otherwise noted.