Catching up on astrophotos

The days are clear, but the mist rolls in about midnight, so it’s been difficult to take any pictures. Here are a few from the last month or so…

NGC7635 (the Bubble Nebula), M52, and NGC7538

NGC7538 is sometimes called “The Brain” or “The Northern Lagoon”. It’s the bright knot at the top center. M52 is the open cluster bottom left of center.

IC1340, part of the Veil Nebula in Cygnus. Called “The Bat” for some reason.
Another view of the Bat, IC1340. More exposures.
IC1396, the Elephant’s Trunk. It’s poorly framed…
IC1396B - Elephant's Trunk
Better framed version. Couldn’t get the colors right.
IC63
IC63, The Ghost Nebula — for its shape.

Someday, maybe, I’ll move to a mountain top, with clear dark skies. For now, I live in haze and city lights.

The Witch’s Broom

NGC6960, The Witch's Broom
NGC6960, The Witch’s Broom Nebula (part of the Veil Nebula

This image is from 18 5-minute exposures. With luck, I’ll get some more tonight and sharpen it up a bit.

Edit: As promised, here’s the same image with additional exposures:

NGC6960, The Witch's Broom
…with 65 sub-exposures

The single exposures aren’t bad on their own. However, the noise in the image is terrible:

NGC6960 raw exposure
Single exposure with all defects exposed

(The electronics in the image sensor caused the odd artifact along the upper right edge.)

For your convenience, here are a couple of 100% crops of the single vs. combined images.

Single exposure:

100% crop
Single exposure, 100% crop

Note the many tiny bright blue dots. These are defects in the image; pixels that fired inappropriately. There are many other fine grain flaws, but the blue dots stand out.

…with 65 sub-exposures:

100% crrop
Combined multiple exposures, 100%crop

The blue dots are gone.

When I started this hobby I thought the purpose of multiple exposures was to make dim objects brighter. But it isn’t — the goal, the magic sauce, is noise reduction. With many exposures, the errors cancel out, and a clearer view of the underlying reality emerges. We hope.

In the single exposure above, the inaccuracies of the individual sensor elements give a gritty character, as if the image was a sand painting made with somewhat impure sand. The image that results from combining the 65 sub-exposures has much less of that gritty appearance.

The Bubble (NGC7635)

The Bubble Nebula
NGC7635 and NGC7654 (M2)

NGC7635, the “Bubble Nebula”, is towards the lower left, and M2 is the open cluster along the upper right side.

The Hubble has, as usual, produced a lovely rendition of the Bubble — I guess we could call it the “Hubble Bubble“.

On a different note, the New Space Telescope has dropped its first images, and they are spectacular, as expected. Ditch astrophotographers such as myself tremble in awe. Several side-by-side comparisons of HST and NST images show wonderful improvements in clarity and detail. Stephan’s Quintet has special significance to me because it is the most difficult object I ever saw visually, back many years ago when my eyes were better and I had a 10″ Dobsonian. It was only discernable with averted vision, but definitely there.

However, the Hubble images are still as exquisite as they ever were. The universe has wonders at every scale — it is a fractal of wonder. The Hubble reveals wonders at its scale. The New Space Telescope reveals wonders at a different scale. And My Little Telescope (MLT) reveals wonders at its scale.

Better M101

M101
M101

Another heroic image 🙂 — 18 hours with a small telescope and poor conditions. Post-processing is minimal — just some brightness and contrast adjustments in gimp to minimize the distracting sky glow.

Life these days is extremely depressing.

Morbius: ‘My poor Krell. After a million years of shining sanity, they could hardly have understood what power was destroying them.’

M51 improved

This image is my deepest view so far of M51. About twelve hours total exposure time, but it represents much more telescope time because I’ve discarded many hours worth. The night before last, for example, out of five hours total time I dumped four, because after I went to sleep fog rolled in, and all the exposures were flat gray.

M51
M51

A close crop:

M51
M51

The dark red coloration is consistent with images on the web, so I presume it is a reflection of reality.

NGC6946, redux

NGC6946
NGC6946

As fate would have it, more light was available last night. Not great, but better.

Here’s the larger view:

Galaxy and Open Cluster
There may be hundreds of stars in the open cluster that don’t show in this image…

NGC6946, the Fireworks Galaxy

Fireworks Galaxy and Flying Geese Cluster
NGC6946 and NGC6939 — the Fireworks Galaxy and the Silk Fan Cluster

NGC6946 is dim. I only had about three hours total exposure; it would be better with twice that. Unfortunately, the weather is sketchy, and I probably won’t be able to collect those photons any time soon.

Stellarium has several fanciful names for NGC6939 — the “Ghost Bush Cluster”, the “Flying Geese Cluster”, and the “Silk Fan Cluster”. I prefer “Silk Fan Cluster”.

This image was cropped to balance the two objects. A closer crop of the galaxy shows lots of potential, but it would take time and good conditions to do it justice:

NGC6946

M13 and M13

M13 and a distant galaxy
M13 and a distant galaxy, NGC6207. Slightly cropped.

There’s a delicate hint of pink in the middle of the cluster — it is probably necessary to expand the picture to the max to see it. The pink is undoubtedly an artifact. (However, Wikipedia states that the brightest star in the cluster is a red giant… Could it be the color comes from that star??? Nah.)

The tiny galaxy to the Northeast (by accident, the orientation is roughly correct), NGC6207,  is quite pretty when seen by the Hubble.

I process images using PixInsight, plus GIMP for the final touch-up. The most important single step in the process is called “stretching” — even with long exposures, an unprocessed image is dim to the point of being almost black. Something like:

unstretched image of M13
Unstretched image of M13

If you maximize the image and look very closely, you will see a few stars (I count 15) and, in the middle, a faint ghost of M13. (I cheated — this image has actually been stretched slightly — otherwise, there wouldn’t even be a ghost!)

Though big telescopes are fabulously expensive and finicky to set up, the computing power necessary for image processing is readily available to the common nerd like me. And a telescope is not required — for example, the enormous trove of Raw Hubble Data is available online, for free.

The Whale and the Crowbar (or Hockey Stick)

NGC4631 and NGC4656 — The Whale and the Crowbar (or Hockey Stick) Galaxies

Another try. Slightly better processing and a dozen more five-minute exposures added. The tiny fuzzy ball above the whale is a companion dwarf elliptical galaxy, NGC4627. All three galaxies are about the same distance from us, and they interact. Hence the odd shapes.