mosqueeto – Remembering Earth-that-was

2022-07-232022-07-26

The Witch’s Broom

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:

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:

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.

2022-07-15

Comet K2

M10 is left of center; K2 is a little lower and on the right side. This picture was taken 14 Jul 2022, just about the comet’s nearest approach to Earth.

I took the picture under desperate circumstances; high fog was crashing my party, and I only had about a half hour to collect these photons. Even worse, the telescope was having trouble pointing (something I will need to troubleshoot when I’m not under time pressure).

It’s a standard weather pattern for this time of year — beautifully clear during the day, with high fog / low clouds developing as the night cools down. It has been like this for a couple of weeks.

2022-07-15

The Bubble (NGC7635)

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.

2022-07-01

Better 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.’

2022-06-29

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.

A close crop:

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

2022-06-092022-06-11

Another Messier Global, M12

How did this happen? What does it mean?

2022-06-082022-06-08

NGC6946, redux

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…

2022-06-07

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:

2022-06-04

La Bomba Volcanica Gigantesca

Volanic bomb on a sea of ash — Fellow passenger observing a rock

I met a traveller from an antique land,

Who said—”Two vast and trunkless legs of stone

Stand in the desert. . . . Near them, on the sand,

Half sunk a shattered visage lies, whose frown,

And wrinkled lip, and sneer of cold command,

Tell that its sculptor well those passions read

Which yet survive, stamped on these lifeless things,

The hand that mocked them, and the heart that fed;

And on the pedestal, these words appear:

My name is Ozymandias, King of Kings;

Look on my Works, ye Mighty, and despair!

Nothing beside remains. Round the decay

Of that colossal Wreck, boundless and bare

The lone and level sands stretch far away.”

— Percy Bysshe Shelley

On Island Lanzarote, the easternmost island of the Canaries. The cinder cone in the background cleared its throat, and La Bomba was born, a shattered visage on the sand.

Lanzarote is entirely composed of wind-blown flat expanses of volcanic ash and lava flows, dotted with low cinder cones. We took a four-mile hike that started over difficult ‘A’a clinkers. One person fell and rose with bloody hands, and a couple decided to turn back.

Volcanic landscape with A'a lava flows — Slightly weathered A’a lava flows

But by the time we reached La Bomba, the trail turned into a wide, level walking path over fine cinders. Effortless.

The hike’s highlight was ‘La Caldera de los Cuervos’ — ‘Cauldron of the Ravens’. It’s a small cinder cone that was home to a colony of ravens; there is a notch blown out of the side so you can walk in.

Entrance to the crater — The notch. A nice trail.

Inside the crater — Looking down into the crater

Bottom of the crater — Inside the crater

Walking back to the bus — Back to the bus, through the vineyards

Vinyards in the cinders — Vineyards in the cinder fields.

The vines are grown in pits; the pits are protection from the constant trade winds. There is no irrigation; the vines get enough water naturally. Lots of hand labor picking the grapes. We didn’t have time to try the wine.

2022-06-04

M13 and M13

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.