Caldwell 68 and Globular Cluster NGC6723 - Adam Lundie - Eatons Hill Observatory

Caldwell 68 and Globular Cluster NGC6723

26-Jun-2016
Caldwell 68 and Globular Cluster NGC6723 thumbnail
Caldwell 68 and Globular Cluster NGC6723
Less than 500 light-years away and blocking light from more distant, background stars in the Milky Way, the densest part of the dust cloud of Caldwell 68 is about 8 light-years long. At its tip is a group of reflection nebulae cataloged as NGC 6726, 6727, 6729, and IC 4812. A characteristic blue color is produced as light from hot stars is reflected by the cosmic dust.

The smaller yellowish nebula (NGC 6729) surrounds young variable star R Coronae Australis. Magnificent globular star cluster NGC 6723 is toward the upper right corner of the view. While NGC 6723 appears to be part of the group, it actually lies nearly 30,000 light-years away.

Image:

  • 36x 240s Luminance 20 flat + 50x dark + 120x bias
  • 21x 240s Red 15 flat + 50x dark + 120x bias
  • 23x 240s Green 15 flat + 50x dark + 120x bias
  • 20x 240s Blue 15 flat + 50x dark + 120x bias

Total exposure 6 hours 40 minutes.

Hardware:

  • Skywatcher Black Diamond ED120
  • SkyWatcher EQ8 Pro Mount
  • QSI 683-ws Camera @ -15C
  • Astronomik Typ 2c LRGB filters
  • Starlight Xpress Lodestar X2 Autoguider
  • Innovations Foresight On Axis Guider

Location:

  • Orange zone in Brisbane, Australia. (Bortle 7)

Software:

  • Planning & camera alignment with Aladin 9
  • Captured with AstroArt 6
  • Guiding with PHD2 + PHD_Dither
  • CCDInspector: Image analysis & rejection
  • CCDStack 2+: Calibrate, align, stack, deconvolution, combine RGB.
  • Photoshop CC: Reduce noise, high pass filter, minimum filter, shadows/highlights, levels, curves, combine L+RGB, color balance.

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