Saturday, June 24, 2017

M20 - Trifid Nebula and M21

The Trifid Nebula (M20 or NGC 6514) is in Sagittarius only a mere 5,200 light-years from Earth.  The object is made of an open cluster; an emission nebula (the lower, red portion), a reflection nebula (the upper, blue portion) and a dark nebula, the apparent 'gaps' within the emission nebula (source: wikipedia).  

This was the first night imaging with the the new Atlas Pro EQ/AZ mount.  I collected 3 min. subframes and the mount was tracking perfectly through the whole session.  I did have one mishap that cost 30 minutes of images but it was my fault.  The computer battery went dead during the session and my backup plan (connecting it to the Black and Decker power pack was also dead.  The third backup plan was to connect an extension cord to the inverter that came with the Rav4.  This worked but I had to have the car running.

When I processed the data I had a lot of scattered reds in the background.  Most often it simply noise in the image, however, there is a lot of nebulosity in this region.  I checked many other images of this region and there was no definitive answer to was it noise or real gas and dust that that my modified camera picked up.  Some images showed it and some did not.  I made the executive decision to lesson it's impact rather than process it away.  There are hints of nebulosity if you look closely.  I did use Fred Espenek's ( image of this region a guide.

I love these two for one objects.  M21 is a tightly packed cluster of about 57 stars located about 4,250 light-years from Earth.   Since it was in the field of view I was able to pick up two Messier objects for my catalog with one imaging session.  With the addition of these two, I now have captured 92 Messier objects for my catalog.  Only 18 are left!

Trifid Crop

Trifid Wide Field

M21 Crop

M20 - Trifid Nebula and M21
Location: St. John's Cemetery, Monroe, CT
Date: 6-20-17
Camera: Canon EOS Rebel T3i(a), Backyard EOS
Telescope: Orion ED80 80mm f/7.5 Apochromatic Refractor Telescope
Barlow: None
Focal Length: 600mm
Focal Reducer: Orion 0.8x Focal Reducer for Refractor Telescopes
Mount: Orion Atlas Pro EQ/AZ Mount
Filter: Astrodon UV/IR, Astronomik UHC
Autoguiding: QHY-5L-II-M attached to an Agena 50mm Guide Scope with Helical Focuser
Exposure:29 x 180s
ISO: 1600
Temp: 20 C
Post Processing: Deep Sky Stacker, Photoshop, Lightroom, Gradient Exterminator, Astronomy Tools, StarTools.

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