IC 4628 (Gum 56, Ced 137b, Prawn Nebula ) in Scorpius

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© Velimir Popov & Emil Ivanov 2013

IC 4628 (Gum 56, Ced 137b, Prawn Nebula) is an emission nebula located south of Antares about 6 000 light-years away and it is about 250 light-years across. It is observed in the southern part of the constellation, just north of the bright open cluster NGC 6231, which is also located in the same galactic environment. It is an HII region that directly receives the radiation of the massive stars which forms the core of NGC 6231 - Scorpius OB1 association. The main ionizing star is, according to a 1984 study, the blue giant HD 152723. Other sources suggest that the ionizing source is the star HD 322417, also a class O5 or O6, although this may be at a distance greater than the region of Scorpius OB1.

Over the last few million years this region of sky has formed many stars, both individually and in clusters. Also visible are many dark structures or cavities, where interstellar matter has been blown away by the powerful winds generated by the nearby hot stars.


Object details

Right Ascension 16:56:55 (h:m:s)
Declination -40:30:44 (deg:m:s)
Distance ~ 6 000 (ly)
Apparent Dimension 90 (arc min)

Image details


Center of field RA 16:57:04 (h:m:s)
Center of field DE -40:26:42 (deg:m:s)
Size 1.37 x 1.37 (deg)
Pixel scale: 1.23 (arcsec/pixel)
Orientation: Up is -178 degrees E of N
Charts and image details obtained from Astrometry.net
Optic(s): 16" f3,75 Dream Corrected Astrograph (DCA)
Mount: Astelco NTM-500 direct drive mount
Camera: Apogee Alta U-16M CCD camera
Filters: Lum, Red, Green, Blue, Ha, OIII and SII Astrodon
Dates/Times: From 3 to17 of May 2013
Location: Namibia-TIVOLI ASTROFARM, S 23° 27' 40,9" / E 18° 01' 02,2"
Exp. Details: L:4x10min, R:3x10min, G:3x10min, B:3x10min, Ha:6x15min, OIII:3x15min
  Bin 1, Total Exposure Time - 265 min (4:25 hours)
More details: Dark and flat frames reduction
Processing: PixInsight / PS
Copyright: Velimir Popov and Emil Ivanov 2013. All Rights Reserved
e-mail: info@irida-observatory.org
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