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Messier 20 or NGC 6514 is a very popular nebula located in the constellation Sagittarius. It consists of three different kinds of nebulosity: emission nebula, the red nebulosity at the center, reflection nebula, the bright bluish nebulosity around the emission nebula and dark nebulae, the dark lanes dividing the emission nebula in three distinct lobes as well as covering up several zones of the reflection nebula. The emission and the reflection nebulosities are active star formation regions. A very young open cluster with the name C 1759-230 is embedded into the emission nebula (and born from the gas in that nebula). The images taken in 2005 by the Spitzer Telescope, an infrared telescope, revealed over 30 stars in embryonic state (in the act of being formed) as well as 120 stars very recently formed that had not been detected in the images taken with visible light cameras. This may make C 1759-230 probably the youngest star cluster in our galaxy.

This image was taken with narrowband filters (Halpha and OIII), as well as several broadband Blue subframes to be blended with the OIII subframes. This was done in order to be able to take an image of a nebula having both emission (ideal for narrowband filters) and reflection clouds (usually only visible with broadband RGB subframes). The colors were mapped: Ha to Red and 14% Blue (to account for Hbeta), OIII to Green and OIII+broadband Blue to Blue.

This image has been selected as AAPOD (Amateur Astronomy Picture of the Day) on January 14, 2017

Additional Information


Name(s): M 20. NGC 6514. The Trifid Nebula

Type: Emission/Reflection Nebula

RA: 18h 02m 35s

Dec: -23º 01’ 54”

Constellation: Sagittarius

Size (arcmin): 29×27

Magnitude: +6.3

Distance: 5,200 ly


Date: 2016-08-28 thru 2016-09-23

Location: iTelescope.net, SSO near Coonabarabran, NSW Australia

Size (arcmin): 37×37

Telescope: Planewave CDK 20” f/6.8

Camera: SBIG STX16803 (4096x4096pix)

Guiding: Astrodon MonsterMOAG off-axis guider

Total exposure: 12h 45m (Ha: 11x30min; OIII: 6x30min; B: 11x15min; RGB (stars): 1.5h)

Processing: CCDStack, Photoshop CC 2015.5

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