Celestial hemisphere:  Southern  ·  Constellation: Sagittarius (Sgr)  ·  Contains:  IC 1283  ·  IC 1284  ·  IC 4715  ·  M 18  ·  M 24  ·  NGC 6554  ·  NGC 6613  ·  Small Sgr Star Cloud  ·  The star 15 Sgr  ·  The star 16 Sgr  ·  The star 17 Sgr
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The Sagittarius Star Cloud, Dan Watt
The Sagittarius Star Cloud
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The Sagittarius Star Cloud

Getting plate-solving status, please wait...
The Sagittarius Star Cloud, Dan Watt
The Sagittarius Star Cloud
Powered byPixInsight

The Sagittarius Star Cloud

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Description

For the longest time I've long enjoyed M24 as a visual observing target, always a pleasure to look at it with binoculars or small telescopes that could take in the whole field. But I've always kind of thought of it as a bright sparkly area of the summer Milky Way, nothing more.  Then one night I decided to point my 20" dob at it and I must have spent hours taking in all the detail. From the Trifid-like IC1284 to the dark dust clouds in IC4715. The cluster right in the middle, NGC 6603 and the planetary nebula NGC6578. There was A LOT going on! 

My favorite part of it is that M24 isn't really a traditional cluster at all but instead a window into the Milky Way. When looking at it my brain always tries to put the dark area around M24 in the background and the star cloud in the foreground but it's actually the reverse. 

So I decided to spend much of the precious summer milky way season working on a mosaic of this region. Needed to get 6 panels to do it justice. 

Gradients were very tough to deal with. I ended up sitting on the data for months because I just couldn't get a satisfactory mosaic. DBE and similar processes were tough because it's such a busy region. It wasn't until I tried out Vincent Peris' multiscale gradient extraction method that I was able to get some useable results. 

I was also able to get a fair amount of HA from my backyard in Los Angeles. Still needed A TON of integration time because even with a 6nm HA filter the light pollution is horrendous. I can only imagine how much HA detail I'd get if I could have imaged it from somewhat dark skies. 

I blended the HA into the RGB image using this continuum method that worked pretty well... still need more practice with it. Very tough to find a good balance that doesn't look fake and splotchy. Still not totally happy with it but I had to call it at some point. 

Did most of the imaging from several new moon trips to a Bortle 2 site in the White Mountains, Grandview Campground. M24 is low to the south so I knew I needed decently dark skies to avoid gradient hell. I believe this took a total of ~12 nights over a few months time.

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Title: HA Continuum image

Description: Kind of nasty, had to do a bit of photoshop clean up to mix this in.

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Title: Widefield reference used for Multiscale Gradient Extraction

Description: This is the image I used to perform the multiscale gradient extraction method. Shot with a Canon 6D and Nikkor 180mm 2.8 lens. 24x300s @ ISO1600

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The Sagittarius Star Cloud, Dan Watt