The Sun 4/18/2017

Although we're well past SolarMax and the solar disk looks blank on many days, it can still be interesting in H-alpha. This is a single-image capture (not a stack) taken with the DS16C and PST-DS. The active area and prominence at the top of the image is sunspot 2644, a returning spot that produced a number of M-Class flares in early April.

The illumination of the image is somewhat uneven. This lack of uniformity is caused by the PST filter's "sweet spot." The DS filter reduces this effect, but it does not eliminate it. For the best aesthetic images of the sun with the PST, it's better to stitch together a mosaic of separate captures of separate areas of the solar disk.

2/18/17 Imaging Session

It's been a while since I posted here. The winter has not been good here in Indiana, and the Spring has been mostly cloudy with clear skies coinciding with full moons and evening events that kept me from the scope.

Here's a few images I captured on an unseasonably warm February evening. These pix were captured with the 8 inch f/4 astrograph and Mallincam DS 16c.

This image shows the Crab as captured by the DS16c. The combination of F/4 scope and large imaging ship captures a very wide field. It's not ideal for the Crab and other small planetary nebulae, but for large objects, like M42 (below), it is a perfect combination.

The wide field is also useful for capturing groupings of objects, as in this image of the Cigar Galaxy and Bode's Galaxy:

The Orion Molecular Cloud

Last night was one of the best we have had all year--above freezing temps (just), decent seeing, high transparency, and little sky glow. I took out the 8 inch, f/4 Newt and the DS 16C. All these images were taken with no dark subtraction, no filters, and were stacks of 20 x 15-second integrations. Of course, there is noise in the images as a result of the "raw" stack, but the images are pretty decent.

The Orion Molecular cloud has many wonderful objects for imaging, and last night's conditions enabled me to capture some of them: the Running Man Nebula, the Flame and Horsehead Nebulas, and, of course, the mighty Great Nebula itself.

A Walk on the Moon

This is a set of lunar images I took with my 125mm MAK and the ASI 120MM imager. The ASI is a very good monochrome imager and matches the MAK pretty well. Images were captured with Firecapture and stacked and processed in Registax.

The first image is of the famous Alpine Valley area (click to see a larger image). The valley is a line extending into the Lunar Alps (Montes Alpes) just above and to the left of center in the image. It is 166 km long and about 10 km wide.

The second image is the crater Copernicus:

Copernicus is 93 km in diameter and has a prominent ray system (the lighter "splashes" around the crater). The terracing of the crater interior is clearly visible in this image. These terraces are the result of landslides as the walls of the crater collapsed. The sloping rampart around the crater is about 30 km across.

Gassendi can be found at the northern edge of Mare Humorum. As you can see, the crater has been filled with lava during the formation of the Mare. The ga…

Large Stack Experiment--M33, M31, NGC6912

Despite a half moon, skies were steady and transparent last night, with still conditions, making it a good night to try some more stacking experiments. The setup was my ZEQ 25 mount, f/4 Newt, and DS16C imager; no filters were used. I upgraded to the latest version of the MallincamSky software, but I was unable to get the dark field capture to work. However, the DS16C is very low noise, so I decided to go ahead and do the experiments anyway. Given that there is no noise correction of any kind, the images are remarkably low noise with little amp glow visible.

Image capture parameters were: Gain: 18; Exposure: 19 seconds; auto white balance. Histogram upper end was 100, lower end varied between 10 and 15, depending on the image.

Stack sizes were:

M33: 2x99-image stacks combined in Nebulosity
M31: 99 images
NGC6912: 99 images

Noise stacking artifacts are visible on the M33 image; the M31 image shows very minor improvement over the smaller stack I captured last Friday (a little more dust …

My Best M31

I captured and processed this image on Saturday night with the remarkable Mallincam DS16C and my f/4 Mallincam Newt. I used integrative stacking plus some minor tweaking (color balance--Photoshop; Curves--Nebulosity) to produce this final image. This combination of imager and scope really delivers!

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…