Wednesday, November 30, 2016

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 gap at around the 3 o'clock position is as low as 200 meters high; the highest part of the crater rises 2.5 km above the surface.

Thursday, November 10, 2016

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 lane detail is visible above the center of the image), suggesting about 25-35 images is the "sweet spot" for good S/N in skies with moderate skyglow.


Tuesday, November 8, 2016

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!