Monthly Archives: November 2014

Emission Nebula NGC6820 with Open Cluster NGC6823

NGC6823-v1

The open star cluster NGC 6823 lies at the centre of the image. It is about 50 light years across and about 6000 light years distant towards the constellation of Vulpecula (the Fox). The cluster is associated with the HII region Sharpless 86 and is embedded within the mixed emission and reflection cloud NGC 6820. Dispersed among the surrounding nebulosity are a host of dark clouds, elephant trunk like pillars and several striking dark globules of gas and dust known as Bok globules. The huge pillars of gas and dust are created by erosion from the hot radiation emitted from the brightest cluster stars. The Bok Globules represent collapsing protostellar cores of gas and dust that will ultimately evolve to form infant stars.

The image was created by mapping the SII, Ha and OIII data to RGB respectively and then adjusted using Photoshop’s Selective Colour tool. Final enhancements were performed using the Sharpener Pro 3 tools and Color Efex Pro 4 filters from the Google Nik collection.

Right ascension: 19h 43m 22s | Declination: +23° 16′ 13″ | Distance: 6,000 Light Years
Field of view: 54 x 37 arcmin

Camera: SBIG ST-10XME
Telescope: APM 152-1200ED F/6.2 with Riccardi x0.75 Reducer
Guiding: Off-axis with Lodestar guider
Filters: Astrodon Ha (3nm), OIII (3nm), SII (3nm)
Exposures: Ha 27 x 20 min, OIII 35 x 20 min, SII 33 x 20 min
Total exposure: 31.7 hours
Image composition: False Colour Hubble Palette (SII, Ha, OIII mapped to RGB)
Scale: 1.49 arcsec/pixel
Image acquired: July – September 2014

Image capture with MaxIm DL, FocusMax, ACP; Image processed with MaxIm DL; Photoshop CS4; Focus Magic; Color Efex Pro 4, Sharpener Pro 3