Tuesday, October 25, 2016

Averaged stacking experiments--Bubble Nebula and M31

Equipment: Mallincam f/4 Newt and Mallincam DS16C.

Here are 3 pix I took using averaged stacking with the DS16C. I used the f/4 Newt, so there is considerable coma distortion. The M31 pic is an averaged stack of 20 integrations. My research and conversations with people who know stacking suggests that averaged stacking reduces overall noise, but "redistributes" it so that fine details are obscured and contrast is reduced. Compare this averaged stack image (20 integrations) with my previously-posted image of M31. Compared to that image, the noise is lower, but the sky background is quite light even after histogram adjustment. My earlier M31 (posted yesterday), was a much smaller stack using additive stacking. As you can see, there's more detail and a darker sky background, but the overall noise is higher. Unfortunately, I did not capture a single pic, but I suspect it would have shown more detail with a little more noise.

I also captured an image made with a large, averaged stack of the Bubble Nebula. The larger image shows how tiny the nebula is in the very wide field of the scope/imager combo. This image was the result of 70(!) (30+20+20) averaged integrations (the 3 stacked images were combined in Nebulosity). The cropped image shows the faint "bubble" nebulosity. Although the noise is lower than a single image, the single image I used to adjust the integration settings showed the nebulosity with more contrast.

Interesting results.

Monday, October 24, 2016

M31 with DS16C

I'm still learning about the DS16C--but what I know, I really like. The cam combines high sensitivity with very low noise and no amp glow. With this cam, you can capture detail fast!

My goal here is not to spend hours producing an image, but to see how good an image can be with fast capture and minimal processing.  Below is an image of M31 captured with the DS16C and f/4 Newt. It is a stack of 3x10-second integration with some level adjustment in Photoshop to darken the background--less than 5 minutes of total work.

Tuesday, October 18, 2016

First Light, Mallincam SkyRaider DS16C

Last night was First Light with the MC SRDS16C--a remarkable, 16 megapixel CMOS color camera which eliminates the Bayer Matrix and combines high sensitivity with low noise.  

My first, out-of-the-box dark field tests showed virtually no noise on 30-second integrations at maximum gain. Lengthening the integration to 1 minute showed a speckling of color noise. The biggest difference between this camera and my others is that even on a 2-minute integration, there is no amp glow! This is remarkable and greatly simplifies long exposures and multiple-exposure stacks that tend to enhance amp glow, even when corrections like DFC are applied unless great care is taken with dark field capture settings.

The images below are significantly "down-rezzed" as the actual images captured are in the 30 to 40Mb range. These were captured with my MC f/4 Newt under almost full moon conditions last night with no filtration. This is a great combination of scope and camera! As you can see, the result is a wide field with minimum vignetting and superb imaging capabilities. I can't wait to try it on more challenging--and more colorful--objects!

The Double Cluster (stack of 3x20-second integrations)

M31 (stack of 2x20-second integrations)

Deneb--the Very First Light Image (1 x 250ms integration)

Thursday, October 6, 2016

A Cosmic Bubble

The Bubble Nebula (NGC 7635) is an H II emission region located in Cassiopeia. The bubble is created by the stellar winds from the nebula's central star. The whole is surrounded by a giant molecular cloud. Both the nebula and the cloud are visible in this image, taken 10.5.16 with the 8 inch f/4 newt and DS 2.3+.

The Saturn Nebula

Running the 14 inch at f/5 with the large DS2.3+ imaging chip results in a relatively wide fov.  This is not a good combination for imaging small, compact planetary nebulas.

This is especially true of the Saturn Nebula (NGC 7009). The nebula was a tiny object in the full image and this rather noisy image is a very small, cropped part of the full image. It's immediately obvious why the object is called the Saturn Nebula. The nebula is formed by the ejection of the outer layers of a low mass star. The characteristic blue/green color is obvious in this image. The internal structure of the object is complex, but unfortunately, that complexity cannot be seen in this image. The object was either invisible or "blown out" in every integration I tried. I am sure that a larger image scale (for example, the 14 without the focal reducer) would stand a better chance of showing this structure.

Glorious Globulars!

There's nothing quite like a globular cluster. In my 14 inch scope, many of the brighter globulars make me feel as if I am falling into the sky. While it's impossible to recreate that feeling with an image, these objects are still impressive.

Here are images of two of my favorite globulars: M15 and M2. M15 is in the constellation Pegasus. It is one of the densest globulars having undergone core collapse. It's central structure may be a shell of stars orbiting a black hole.

M15 through the 14 inch with the DS2.3+ imager
M2 is found in Pegasus. It is one of the largest globular clusters and shows an slightly elliptical shape with a dense center.


Wednesday, October 5, 2016

The Eagle Nebula (Messier 16)

The Eagle is an iconic object and home to the famous Hubble-imaged Pillars of Creation. Also an H II star forming region, the latest research suggests that the Pillars may have already been destroyed by a schockwave from a supernova explosion 8000 to 9000 years ago. We will probably have to wait another thousand years to find out if the relatively slow-moving shockwave from the supernova riped them to shreds.

The Lagoon Nebula (Messier 8)

As in the last two posts, the Lagoon is another star-forming region. An H II emission nebula, the Lagoon is a dramatic object. Approximately 110 x 50 light years in size, it is an extensive object. The open cluster NGC 6530 is in the foreground. This is another image taken with the !4 inch at f/5 with the DS 2.3+.

The Trifid Nebula (Messier 20)

Taken with the 14 inch and DS2.3+, the Trifid is a lovely sight. At f/5, the nebula fills the FOV of the imager. The Trifid is an H II region in Sagittarius. It is a combination emission, reflection, and dark nebulas, plus a star cluster. The dark lanes that define the lobes of the nebula are designated Barnard 85.

The Iris Nebula (Caldwell 4)

The Iris Nebula is a bright reflection nebula. The cluster within the nebula is NGC 7023.  This image was taken with my MC 2.3+ and 8 inch f/4 Newt.

The Wizard Nebula (NGC7380)

The Wizard Nebula is a tough object to image in the haze of Indiana skies and the light pollution of my small home town. However, the tell-tale red color of the nebula can sometimes to pulled out of the skyglow with a little processing.

The nebula surrounds a cluster of new, young stars. If you look closely below and right of center, you can just make out the shape of the wizard's face and hat which give the nebula its name.