Winter Sky in Moonlight


Orion & Winter Stars over Old House

Earlier this week I shot a similar scene with the Moon in the photo, when it was near Jupiter. This is the same sky but 5 days later, on January 26, with the Moon now out of the picture, but serving to light up the landscape.

This is the old house on my property that serves as an occasional foreground for test nightscapes. In this case, I was testing my veteran Canon 5D MkII camera against a new Canon 6D. This shot with the 5D MkII had the best arrangement of clouds and stars and works as a decent enough shot on its own.

You can see Orion dodging the clouds, with Sirius at left, and Aldebaran, Jupiter and the Pleiades at upper right.

So what of the tests? Initial impressions are that as far as noise is concerned (always the bane of astrophotographers) the new full-frame Canon 6D improves upon the 5-year old Canon 5D MkII by a factor of two. Noise looks to be about one f-stop better in the 6D, no doubt due to its new Digic V on-board processor.

What this means is:

• Images taken with the 6D at ISO 6400 have a similar level of noise as do images taken at ISO 3200 with the 5D MkII. ISO 3200 images with the 6D look like ISO 1600 images with the 5D MkII, and so on.

• So, if you were happy with shooting at ISO 1600 with the 5D MkII before, you could now shoot at ISO 3200 with the new 6D and get similar results, but with the added benefit of being able to cut your exposure times in half, always a nice thing to do.

• Or conversely, you could continue to shoot with the Canon 6D at ISO 1600 for the same exposure times as before but get shots with much less noise in them. Always a good thing, too!

It’s great to see camera state-of-the-art advancing.

– Alan, January 27, 2013 / © 2013 Alan Dyer

Zooming into Canis Major – #3


NGC 2359 Thor's Helmet NebulaIn the third instalment in my trilogy of Canis Major zooms, I present this close-up of another neat nebula in the Great Hunting Dog, called Thor’s Helmet.

You can tell just by the colour that this is a different type of nebula than the typical red hydrogen gas clouds, such as the Seagull Nebula of my previous post. Yes, this is glowing gas but this nebula originates from a different source than most. Rather than being a site where stars form this is a nebula surrounding an aging star, a massive superhot star that is shedding shells of gas in an effort to lose weight – or mass as we should say.

Intense winds from the star blow the gas into bubbles, and cause it to fluoresce in shades of cyan. The central star is one of a rare stellar type called a Wolf-Rayet star, named for the pair of French astronomers who discovered this class of star in the 19th century. WR stars are likely candidates to explode as supernovas.

This particular Wolf-Rayet nebula, catalogued as NGC 2359, has a complex set of intersecting bubbles that, through the eyepiece, do take on the appearance of a Viking helmet with protruding horns, like you see in the Bugs Bunny cartoon operas! It’s a neat object to look at with as big a telescope as you can muster. And, as you can see, it’s rather photogenic as well, embedded in a rich field with faint star cluster companions.

– Alan, December 28, 2012 / © 2012 Alan Dyer

Zooming into Canis Major – #2


IC 2177 Seagull Nebula Complex

Zooming in closer yet again to the field in Canis Major I showed in my previous post, I’m now framing the large nebula known as the Seagull. Perhaps you can see him flying through the stars.

The catalog number for this object is IC 2177, but the bright round nebula at right (the head of the Seagull?) is object #1 in the catalog of Australian astronomer Colin Gum. It’s also object #2327 in the familiar NGC listing that all stargazers use.

Some of this nebulosity is just visible through a small telescope, especially with the aid of a nebula filter than accentuates the emission lines – the colours – emitted by these kinds of glowing gas clouds.

This is certainly a photogenic field, with a nice mix of pinks, blues, purples and deep reds.

I used my 4-inch (105mm aperture) f/5.8 apo refractor to shoot this target, so the field is fairly narrow, framing what a telescope would show at very low power.

(FYI – The image info listed at left, automatically picked off the image’s EXIF data by the WordPress blog software, fails to record the focal length of the optics properly, as I didn’t use a standard camera lens but a telescope the camera doesn’t know about.)

I’ve been after a good shot of this object for some years, but haven’t been successful until this past observing run in Australia, in December 2012. While I can see and shoot the Seagull Nebula from home in Alberta, it’s always very low in my home sky. From Australia the challenge was framing the field with the Seagull overhead at the zenith. Just looking through the camera aimed straight up took some ground grovelling effort. Plus avoiding having the telescope hit the tripod as it tracked the object over the hour or so worth of exposures – typically 4 to 5 that I then stack to reduce noise.

– Alan, December 28, 2012 / © 2012 Alan Dyer

 

Zooming into Canis Major – #1


M50 - M46/M47 Area Bino Field

My last post featured a wide view of Canis Major. Here, we zoom in closer to one of the most interesting regions in that constellation, filled with nebulas and clusters.

The prominent red arc is the Seagull Nebula, aka IC 2177. Above and to the right of the Seagull is a clump of stars called Messier 50, which lies over the border in the constellation of Monoceros the Unicorn.

At the lower left edge of the frame sits a pair of dissimilar star clusters, Messier 46 (the left one) and Messier 47 (the right one). M46 is a dense rich cluster of stars while M47 is brighter but looser and more scattered.

Several other non-Messier clusters punctuate the field. This is a great area of sky to explore with binoculars.

Just below centre you might see a small green-blue patch. That’s the nebula called Thor’s Helmet, or NGC 2359, a fine telescopic object.

If you get a clear night this season when the Moon is out of the way and you can head to a dark sky, Canis Major, the Hunting Dog, is a great hunting ground for deep-sky fans.

As the data at left shows, I shot this with a 135mm telephoto lens, giving a field of view similar to what binoculars would show.

– Alan, December 28, 2012 / © 2012 Alan Dyer

Canis Major and the Dog Star


Canis Major from Australia (50mm 5DII)

Shining in the southern sky these nights are the stars of Canis Major, the big hunting dog of Orion the Hunter. Among them is the famous Dog Star, Sirius, the brightest star in the night sky.

Can you see a dog outlined in stars? Sirius marks his head – or it is sometimes depicted as a jewel in his collar. His hind legs and tail are at the bottom of the frame.

I shot this earlier this month from Australia, where Sirius and Canis Major stand high overhead. From northern latitudes you can see these stars due south low in the sky about midnight. Sirius is hard to miss, often sparkling through many colours as our atmosphere distorts its light. But as the photo shows, it is really a hot blue-white star. While it is intrinsically a bright star, much of its brilliance in our sky comes from its proximity, only 9 light years away from us.

For this portrait of the celestial canine I used a 50mm “normal” lens. The atmosphere provided some natural haze this night, to add the glows around the stars accentuating their colours.

This area of sky also contains several nebulas, notably the red arc of the Seagull Nebula to the left of Sirius. Below Sirius you can also see the star cluster Messier 41, a good target for binoculars.

Toward the left edge of the frame you can see a pair of star clusters, Messier 46 and Messier 47, two other excellent binocular objects in the Milky Way, which runs down the frame to the left of Canis Major. The dog is just climbing out of the Milky Way after a swim in this river of stars.

– Alan, December 28, 2012 / © 2012 Alan Dyer

 

Sailin’ Toward the Moon


For the past week I was on a cruise ship in the Caribbean, on a “cruise and learn” voyage, serving as one of the guest speakers to a group of astronomy enthusiasts who wanted an immersive vacation learning about the latest in astronomy research and, in my presentations, about the hobby side: choosing a telescope and doing astrophotography. The cruise was organized by Insight Cruises and by Sky and Telescope magazine.

The trip went great, with fabulous weather all along, and a welcome break to an awful winter in the north. However, a cruise ship is not the best place to actually do astrophotography!

This is a shot taken on Friday, March 11, from the upper deck and bow of the ship, the Holland America Line’s “Nieuw Amsterdam,” as we sailed on a northwest course back to Fort Lauderdale from our most southerly port of call in St. Maartens in the eastern Caribbean. The Moon is overexposed at right, and is directly ahead of us, making it look like we were sailing toward the Moon. At left is Orion and Canis Major, tipped over on their sides compared to our northerly view. This was from a latitude of about 20° North.

To keep the stars looking like stars (and not seagulls) and freeze the rolling of the ship, I had to bump the camera up to ISO 6400 and use a 5 second exposure at f/2.8 (wide open) with the 16-35mm lens. Not the best combination of settings, but it’s what it took to capture the “seascape” night scene.

— Alan, March 13, 2011 / Image © 2011 Alan Dyer

Canis Major Hopping


On one of the few clear nights so far this winter I was able to make Canis Major obey for a while and pose for a shot of the canine constellation hopping along my horizon in the south. From my latitude of 51° N he never appears high in the sky, though the placement on the horizon does make for a photogenic winter scene. Here, you can see the Messier star cluster M41 just below Sirius, the Dog Star, the brightest star in the night sky and the bright jewel in the collar of Canis Major (according to some depictions of the constellation). This is a stack of five 4-minute exposures  with the Canon 5D MkII at ISO 800 and a 50mm Sigma lens at f/2.8, plus a single 4-minute exposure with the Kenko soft filter to add the enhanced hazy star glows.

– Alan, January 2011 / Image © 2011 Alan Dyer