February 21, 2011 – The Amazing Sky

February 21, 2011February 21, 2011

Testing New Gear

Now and then I have the opportunity to test new equipment for astrophotography. That can be both a blessing and a curse — I get to try out new gear before I buy it to see if it really works first, which is nice. But if the equipment doesn’t work well, I might have wasted some valuable nights with little to show for it but some poor photos and lots of frustration. Not so with the gear pictured here. The Celestron CGEM mount, tested for SkyNews magazine, worked great, tracking very well and serving as the platform I used in late 2010 for a lot of astrophotos over two dark of the Moon periods. At about $1500 this is a superb entry-level mount for anyone serious about astrophotography.

I also can praise the Celestron NexGuide autoguider (with the glowing screen at right), shown here on a William Optics 66mm guidescope. It, and its near twin, the Synta SynGuider, worked very well — these are autoguiders to provide exact tracking of the mount over long exposures, a necessity even in the digital age. Unlike many autoguiders, these units are “stand-alone,” requiring no additional computer and able to run for many nights off a typical 12-volt power pack. They are great for use in the field. What’s more, the new autoguiders are quite low cost (~$300) compared to the $1000+ cost of previous models with similar capabilities. I reviewed these units for Sky and Telescope and for SkyNews.

The scope shown here is a favourite of mine, the A&M (now Officina Stellare) 105mm f/6 apo refractor, a beautiful Italian-made “designer scope” with first-class optics. It is a terrific visual and imaging telescope, though a little large for its aperture.

For more details about recommended autoguiders, see the website I developed to support The Backyard Astronomer’s Guide and follow the links to the Chapter 13 entries on astrophoto gear.

February 21, 2011

The Wonderful Winter Sky

While I took this image a year ago in early 2010, I thought I’d post this up now, with the new blog now underway. This is a mosaic of what surely ranks as one of the most amazing areas of sky — the vast panorama of the night sky visible in the northern hemisphere each winter. Here we see more bright stars than at any other season of the year, in the constellations (in clockwise order) of Orion, Canis Minor, Gemini, Auriga, and Taurus. Canis Major and its luminary, Sirius, are just off the bottom of the frame.

This is a 4-panel mosaic, each panel consisting of four 4-minute exposures plus two 4-minute exposures with a soft diffuser filter to add the star glows. Each was taken at ISO 800 with the Canon 5D MkII and a 35mm lens at f/4. Slight haze, changing sky fog, and changing elevation of the fields make it tough to get consistent colours across the sky during the couple of hours of exposure time needed to grab the images for such a mosaic, especially from my home latitude. But this attempt worked pretty well and records the wealth of bright red and dark nebulosity throughout this area of sky, a region of the Milky Way in our spiral arm but a little farther out from the centre of the Galaxy than where we live.

February 21, 2011February 21, 2011

The Neglected Small Magellanic Cloud

It sits not far away in the deep southern sky from its larger counterpart, but it must feel rather inferior and sadly neglected. Pity as this object does have lots to offer.

This is the Small Magellanic Cloud, a satellite galaxy to the Milky Way and a companion to the Large Magellanic Cloud — each is named for Ferdinand Magellan who noted them on his pioneering circumnavigation voyage of the world in the 16th century. The Small Cloud doesn’t contain the number and complexity of nebulas and clusters as does its larger brother, but it does have some lovely offerings, like the complex of cyan-coloured nebulas and related clusters at top.

However, the notable sights in this area of sky aren’t actually part of the SMC. The two globular clusters in the field lie much closer to us. NGC 362 is a nice globular at top, but it pales in comparison (every such object does) next to the amazing object known as 47 Tucanae, or NGC 104, the huge globular cluster at right. It is a wonderful sight in any telescope.

This is a stack of five 7-minute exposures with the Borg 77mm f/4 astrograph and Canon 5D MkII at ISO 800. I took this on my astrophoto trip to Australia in December 2010, a season when this object is ideally placed for viewing. Most times of the year, the SMC is dragging close to the horizon and lost in the murk, as least for shooting. That’s another reason the poor old SMC gets no respect!

February 21, 2011February 21, 2011

The Wonder-filled Large Magellanic Cloud

It occupies only a binocular field or two in the sky but … Wow! What a field it is! This is one of the objects that makes a trip to the southern hemisphere for astronomy worth the trek alone. This satellite galaxy of our Milky Way is visible only from south of the equator. It contains so many clusters and nebulas, many in the same telescope field, that just sorting out what you are looking at takes a good star atlas (most don’t plot this region well). This is one of my best shots of the “LMC,” taken on my December Oz trip. It is with the Borg 77mm f/4 astrographic lens/telescope and the filter-modified Canon 5D MkII, that picks up much more red nebulosity (that emits deep red wavelengths) that stock cameras don’t record well.

Even so, I’m always amazed at how so many nebulas in the LMC, and in its smaller counterpart, the nearby Small Magellanic Cloud, record as magenta or cyan, rather than deep red. The most prominent object is the Tarantula Nebula at left of centre. It is an amazing sight in any telescope, especially with a nebula filter.

This is a stack of five 7-minute exposures at ISO 800, with the scope on the AP 400 mount and guided with the SG-4 autoguider. This is a single image, framed to take in all the best stuff of the LMC. But to really get it all in with any detail requires a multi-panel mosaic. I’ve done those on previous trips and was hoping to re-do one on this last trip, with the better, sharper camera, the 5D MkII, and with the LMC higher in the sky than on earlier trips. But the lack of clear nights curtailed my plans.

But I’m happy with this one. Nice and sharp and with oodles of nebulosity. But one can never exhaust what this object has to offer, both for imaging and for just looking with the eyepiece. So there’s always next time!

February 21, 2011February 21, 2011

Imaging Down Under in Oz

I like shooting in Australia as I have the good fortune of having family there who kindly allow me to store equipment down under. On each trip over the last decade or so, I’ve brought down various bits of gear, not to mention clothing and other necessities, to be left on site for the next shooting expedition. Now, when I go, I just have to take camera gear, a computer & gadgets, and a couple of days clothing. All else is already there: an Astro-Physics 400 mount, an AP Traveler 105mm apo refractor, a 10-inch compact Dobsonian reflector, and all kinds of accessories, eyepieces, power supplies, adapters, etc. etc. The gear fills several watertight and dust proof storage bins as well as a large golf case brought down originally in 2002.

Each trip usually means taking a new autoguider system as well, since the technology changes so much from trip to trip. In December 2010 I brought two systems, the Santa Barbara Instruments SG-4, shown here, with its e-finder lens, and the Orion Starshoot with a small Borg 50mm guidescope, as a back up just in case the stand-alone SG-4 did not work in the southern hemisphere on a mount it had not been calibrated on and had never “seen” before. I needn’t of worried – the SG-4 worked beautifully — perfectly guided shots with a push of a button. Stunning!

But it is an item I have to take back and forth — like the cameras, it’s all a little too costly to have multiple copies in both the northern and southern hemispheres, at least vs. the size and weight involved in packing and carrying them. With mounts and scopes there is no question — yes, they are costly but there is no way I’m hauling all that gear back and forth for every trip. So at home, I have other mounts and scopes to take the role of the wonderful AP gear that has emigrated to Oz.

February 21, 2011February 21, 2011

The Dark Clouds of Taurus

An area of sky often neglected but ideal for digital imaging is the region of Milky Way in Taurus and Auriga. Threaded through this area of sky are large lanes of dark interstellar dust, forming cold molecular clouds out of which stars form. This complex is close, only 400 light years away, in our spiral arm of the Galaxy, and so is spread out over a wide area of sky. Only piggybacked cameras with normal and wide-angle lenses capture it. But today’s digital cameras are able to record these kinds of dark nebulae as more than just dark holes in the sky — they have colour, usually shades of reddish-brown.

This is a shot from January 2011 from my home backyard, and takes in all of Taurus, most of Auriga and southern Perseus, with the Pleiades at right and the Hyades below.

February 21, 2011February 21, 2011

Hazy Hyades

Here’s a photogenic rendering of a classic northern winter sky object, the Hyades star cluster in Taurus. The Kenko Softon filter added the star glows and punched out the subtle colour variations in the stars. Note how the Hyades stars come in shades of blue and white. The yellow star is Aldebaran, the eye of Taurus the Bull and an interloper here — Aldebaran is actually halfway between us and the Hyades, which lie about 150 light years away, and are true cluster of stars moving together through space. Note the much more distant and smaller star cluster, NGC 1647, at left.

February 21, 2011February 21, 2011

Fuzzy Constellations

I’ve tried for years to create the effect of fuzzy haloes around stars to pop out the brighter stars and make the constellation pattern more obvious. It’s the “Akira Fuji” effect, named for the ace Japanese astrophotographer who has long perfected the technique with beautiful and widely-published results. I’ve tried various soft focus and diffusion filters, scratched UV filters, vaseline-smeared filters, breathing on filters, etc., etc. None have worked well. Till now.

The Kenko “Softon” filter offered by Hutech Scientific works fabulously well! It’s a tough filter to find in local camera stores here — but Hutech sells it. And it really changes the way I do constellation shooting, making any previous shots obsolete. I take several shots without the filter then one or more of the same exposure with the filter in place. I stack the two types of exposures in Photoshop, with the fuzz-filter layer blended with a Lighten mode to a varying opacity to “dial in” the level of fuzziness that looks good. Too much and it looks overdone and fake.

The technique also pops out the star colours, like here on red Betelgeuse amid the blue-white stars of Orion. This was from January 2011 from my backyard and is a stack of four 5-minute exposures w/o filter and one with. All with the Canon 5D MkII and 50mm Sigma lens, a terrific combination for constellation portraits.

February 21, 2011February 21, 2011

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.

February 21, 2011February 21, 2011

After the Blizzard

We’ve certainly had our share (more than our share!) of snowstorms and blizzards so far this winter, though nothing like people down east have experienced. The one saving grace is that after the storm the sky often clears beautifully. In this case, on January 30, 2011 we had very clear blue skies, but filled with ice crystals of just the right shape (hexagonal) and orientation to produce a classic solar halo, with prominent sundogs on the 22° halo and a hint of an upper tangent arc, or is it an upper Parry arc? A trace of a circumhorizontal arc is also visible parallel to the horizon. Solar haloes are fascinating and often unique — each one can display a slightly different set of halo phenomena.

The website Atmospheric Optics gives great information and reference works.