Observations of M20

These are the observations available for M20. If you have any of your own that you'd like to submit we'd love to put them on the website.

• The Triffid Nebula (M20) in Sagittarius

  Image Courtesy of David Davies, Cambridge, UK. For more images from David please visit his Flickr Photostream .

  David's Observation Notes.

  June and July are very difficult times for astronomers with no astronomical darkness and just two hours of barely usable skies between 12 midnight and 2 am; by 2:30 am the coming dawn is lighting the north eastern sky.

  The attached image of M20 was captured over two nights on 1 and 3 July. M20 is a tricky target in the UK as it doesn't rise above 15 degrees altitude and so is not visible for long. Also, the low altitude means that M20 is in the murky atmosphere close to the horizon. I was keen to try M20 as I managed to image it two years ago with my ED120 refractor and wanted to see what the how the Ritchey Chretien telescope would perform.

  The Triffid Nebula is a star forming region in Sagittarius similar to the Orion nebula. At its centre is a multiple star system designed HN 40 which, I have read, contains six components, one of which is a hot blue giant star (spectral type O7) that is flooding the region with UV radiation, ionising the interstellar hydrogen gas, and producing the pink nebula. Further out, cooler stars are illuminating dust and gas producing the blue reflection nebula.

  In this image I have managed, with a little image processing, to just about resolve five of the six components of HN 40.

  To capture this image I sacrificed resolution for increased camera sensitivity and captured the image at 2 x 2 binning, giving an image scale of 1.36 arc seconds per pixel. The two-minute exposures just saturated the brightest stars on the luminance frames.

  Image Details

  40 minutes luminance & 20 minutes each of RGB data in 2-minute subs; The image is a crop at 37 x 28 arc minutes at 1.36 arc seconds per pixel

  Equipment

  Telescope

  8-inch Ritchey Chretien at f/8.

  Camera

  QSI 583 plus Astrodon RGB filters and Lodestar guider.

  Mount

  Modified Skywatcher NEQ6

  Software

  Scopefocus; PHD2: EQMOD; Carte du Ciel; Deep Sky Stacker, PixInsight; Photoshop CC2015

  David Davies - (5 July 2016).