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Contains:  M 20, NGC 6514, Trifid nebula
Getting plate-solving status, please wait...
Trifid Nebula - Messier 20, 


            Bruce Rohrlach
Trifid Nebula - Messier 20
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Trifid Nebula - Messier 20

Technical card

Imaging telescopes or lenses: Skywatcher 200P 200mm/f5 NEQPro6

Imaging cameras: ZWO 1600mm Cooled Pro

Mounts: SkyWatcher NEQPRO6 Synscan GOTO

Software: Adobe Photoshop Lightroom CC  ·  AstroPixel Processor

Filters: ZWO Blue 36mm  ·  ZWO Red 36mm  ·  ZWO Green 36mm

Dates:June 27, 2019

ZWO Blue 36mm: 240x15" (gain: 200.00) -20C bin 1x1
ZWO Green 36mm: 240x15" (gain: 200.00) -20C bin 1x1
ZWO Red 36mm: 240x15" (gain: 200.00) -20C bin 1x1

Integration: 3.0 hours

Darks: ~50

Avg. Moon age: 24.08 days

Avg. Moon phase: 30.07%

Bortle Dark-Sky Scale: 5.00

Basic astrometry details job: 2785442

RA center: 18h 2' 26"

DEC center: -22° 57' 28"

Pixel scale: 1.418 arcsec/pixel

Orientation: 67.615 degrees

Field radius: 0.499 degrees

Resolution: 1967x1599

Locations: Lysterfield, Melbourne, Victoria, Australia

Data source: Backyard


A test to see how well collimated I am after removing the mirrors for cleaning then re-installing the mirrors in the Newtonian OTA. Not very well collimated it turns out. Or I have a tilt issue. So as pixel peepers can see I have a veritable donut factory happening on the left side of both images with the stars not forming nice pin-pricks but small donuts. The stars on the right side of the Trifid Nebula are a bit better. Always something to troubleshoot in this game.

This is 3 hours exposure on the Trifid Nebula using RGB filters with an ASI1600mm Pro. So 240 x 15 second subframes for each of the Red, Green and Blue filters (=720 sub-frames in total) from Lysterfield, Melbourne. The edges of the Trifid Nebula need more exposure time to bring them out better.

The Trifid Nebula (in Sagittarius) is an unusual object, being a combination of an open star cluster, an emission nebula (the pink part), a reflection nebula (the fainter blue part) plus a dark nebula which comprise interstellar dust grains that block light and produce the trifurcated pattern within the pink emission nebula (and hence the name Trifid nebula).

These colourful gas clouds (imaged in true colour here) are the spawning ground of stars and their planetary systems.



Bruce Rohrlach
License: None (All rights reserved)

Sky plot

Sky plot


Trifid Nebula - Messier 20, 


            Bruce Rohrlach