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…

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:


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.”


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.

La Caldera de los Cuervos
La Caldera de los Cuervos. The notch is on the right side.
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.

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.

NGC4565, the Needle Galaxy


There are at least three other galaxies visible in this picture. IC3571 was a dim, dim smudge on the left side of NGC4565 that I tried hard to preserve as I processed the image. But alas, it did not survive the harsh contrast enhancement steps.

Here is an annotated full frame. Some of the other galaxies in the region are visible.

Annotated full-frame view
Annotated full frame

On another topic, yesterday I took possession of hearing aids for the first time. (As I type this, I hear keyboard clicks — I didn’t notice them before.)

It turns out that I have insurance coverage for hearing aids, so I got good ones — Bluetooth enabled, with extensive customization controlled via a smartphone app. They work quite well as music earbuds, at least for certain types of music. Solo guitar sounds fantastic. Noise-canceling features I haven’t explored yet. I can’t get over how loud everything is, especially the coffee grinder. Persimmon the Parrotlet is a terror now — I used to think she (it?) was a quiet bird, but now I know the volume was in the high frequencies.

Here’s Persimmon chewing on a chicken bone:

Persimmon eating a chicken leg
Persimmon gnawing on a chicken bone

We thought she would be interested in the watermelon scraps.

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.

Iris Nebula, NGC7023

Iris Nebula
Iris Nebula

Reprocessed with yet more data. I don’t know that this is significantly better than my previous results ( here and here and here ). But NGC7023 is a fascinating object, and I will probably return to it for the rest of my life. As always, the images available from Wikipedia are worth a pause.



IC2574 is the faint smudge in the center, 13 million light-years away. A dim dwarf spiral galaxy. According to Wikipedia, approximately 90% of its mass is dark matter.

Taken with a 110mm F/7 refractor. Total exposure time is about 13 hours.

Annotated IC2574
An annotated version




Sometimes referred to as “the Sunflower Galaxy”. This image has about 7 hours total exposure time.  It is quite a pretty galaxy — if you zoom in (ie, click on the picture), it looks like a swirl of altocumulus clouds on a spring day.