The Wonder-Filled Winter Sky


Mosaic of the Wonder-filled Winter Milky Way

The sky of December contains an amazing array of bright stars and deep-sky delights.

At this time of year we peer out toward the edge of our Galaxy, in the direction opposite to what we see in July and August. Even though we are looking away from the centre of our Galaxy, the Milky Way at this time of year contains a stunning collection of sights – for the naked eye, binoculars or a telescope.

I can’t list them all here, but most are in the lead image above! The image is a mosaic of the northern winter Milky Way, including the brilliant stars and constellations in and around Orion the Hunter.

The Milky Way extends from Perseus in the north at top, to Canis Major in the south at bottom. Throughout the scene are dark lanes and dust clouds, such as the Taurus Dark Clouds at upper right.

The Milky Way is dotted with numerous red “hydrogen-alpha” regions of emission nebulosity, such as the bright Rosette Nebula at lower left and the California Nebula at upper right. The curving arc of Barnard’s Loop surrounds the east side of Orion. Orion is below centre, with Sirius, the night sky’s brightest star, at lower left.

The constellation of Taurus is at upper right and Gemini at upper left. Auriga is at top and Perseus at upper right.

There’s an unusually bright area in Taurus just right of centre in the mosaic which I thought might be an image processing artifact. No. It’s the Gegenschein – a glow of sunlight reflected off comet dust directly opposite the Sun.

Two highlights of this sky that are great regions for binoculars are the Hyades cluster in Taurus ….

The Hyades Cluster with Aldebaran
The Hyades open star cluster in Taurus with the bright star Aldebaran, not a part of the cluster iteslf. The smaller and more distant cluster NGC 1647 is at left. This is a telephoto lens image taking in a field similar to binoculars, and is a stack of 5 x 2.5-minute exposures with the 135mm lens at f/2 and Canon 5D MkII camera at ISO 800, plus two other exposures taken through the Kenko Softon filter to add the star glows. Taken from Quailway Cottage on Dec 7, 2015 using the iOptron Sky-Tracker.

…and the Belt and Sword of Orion.

The Hyades – the face of Taurus – is one of the nearest and therefore largest open star clusters.

Orion the Hunter, who battles Taurus in the sky, contains the famous Orion Nebula, here overexposed in order to bring out the much fainter nebulosity in the region.

The magenta and blue arcs in the image below are photographic targets, but the bright Orion Nebula in Orion’s Sword is easy in binoculars, shining below the trio of his Belt Stars.

Orion Belt and Sword Mosaic
A mosaic of the Sword and Belt region of Orion the Hunter, showing the diverse array of colourful nebulas in the area, including: curving Barnard’s Loop, the Horsehead Nebula below the left star of the Belt, Alnitak, and the Orion Nebula itself as the bright region in the Sword. Also in the field are numerous faint blue reflection nebulas. The reflection nebula M78 is at top embedded in a dark nebula, and the pinkish NGC 2024 or Flame Nebula is above Alnitak. The bright orange-red star at far right is W Orionis, a type M4 long-period variable star. This is a 4-panel mosaic with each panel made of 5 x 2.5-minute exposures with the 135mm Canon L-series telephoto wide open at f/2 and the filter-modified Canon 5D MkII at ISO 1250. The night was somewhat hazy which added natural glows on the stars. No filter was employed here. The camera was on the iOptron Sky-Tracker for tracking but no guiding. Shot from outside Quailway Cottage near Portal, Arizona, Dec 7, 2015. All stacking and stitching performed in Photoshop CC 2015. Stacking done with median combine stack mode to eliminate geosat trails through the fields.

For us in the northern hemisphere, Orion and company are winter sights. But for those down under, in the southern hemisphere, this is the summer sky. So pardon the northern chauvinism in the title!

Either way, on a dark, moonless night, get out and explore the sky around Orion.

TECHNICAL:

I shot the segments for the main mosaic at top on a very clear night on December 5, 2015 from the Quailway Cottage at Portal, Arizona. This is a mosaic of 8 segments, in two columns of 4 rows, with generous overlap. Each segment was made of 4 x 2.5-minute exposures stacked with mean combine stack mode to reduce noise, plus 2 x 2.5-minute exposures taken through the Kenko Softon filter layered in with Lighten belnd mode to add the star glows. Each segment was shot at f/2.8 with the original 35mm Canon L-series lens and the filter-modified (by Hutech) Canon 5D MkII at ISO 1600, riding on the iOptron Sky-Tracker. All stacking and stitching in Photoshop CC 2015. The soft diffusion filter helps bring out the star colors in this area of sky rich in brilliant giant stars.

— Alan, December 11, 2015 / © 2015 Alan Dyer / www.amazingsky.com

Venus and the Comet


Comet Catalina near Venus (Dec 9, 2015)

Comet Catalina sports two tails as it moves past Venus in the dawn sky.

This was the view this morning, December 9, from my site in Arizona, of Comet Catalina near Venus in the dawn sky. This is a telephoto lens shot that provides a view similar in size to what binoculars show.

However, the blue ion tail visible here stretching back several degrees is mostly a photographic target. Visually, just Catalina’s short, stubby dust tail at lower right is obvious.

The ion tail points away from the Sun, while the dust tail extends along the comet’s orbit, showing where the comet has been.

The view, both visually and photographically, of the comet will improve as it climbs higher into the eastern morning sky and as it moves away from the glare of Venus. The Moon is also now gone from the dawn, at least for the next couple of weeks.

The comet is dimmer than expected but should at least maintain this brightness for the next month or so.

Technical:

This is a stack of 5 x 90-second exposures, taken with the 135mm telephoto and 1.4x extender for a focal length of 190mm, at f/2.8 and with the Canon 5D MkII at ISO 1600, tracked on the iOptron Sky-Tracker. Two other exposures, of 15s and 1s, were blended in with luminosity masks to reduce the glare of Venus to a smaller size.

— Alan, December 9, 2015 / © 2015 Alan Dyer / www.amazingsky.com

Comets, Conjunctions, and Occultations, Oh My!


The Moon, Venus and Comet Catalina

What a morning of sky sights, both before dawn and after sunrise.

December 7 – This was the prime day I came to Arizona to enjoy, to be better assured of clear skies. As it turned out this will likely be the cloudiest day of the week here, but skies were clear enough for a fine view of a conjunction and an occultation. The comet was a bonus.

Waning Moon and Venus Rising in Conjunction
This is a stack of 5 exposures: 30, 8, 2, 0.5 and 1/8s, blended with luminosity masks as HDR would not blend images with such a large range of brightness and content, with the shortest exposures having almost no content execept for two bright objects! The camera was on the iOptron Sky-Tracker to follow the sky and keep the sky targets stationary and aligned, thus the blurred foreground. All with the 135mm lens at f/2.8 and Canon 6D at ISO 400.

At 4 a.m. the waning crescent Moon rose accompanied by Venus, as the two worlds appeared in close conjunction in the pre-dawn sky. The view above captures the scene as the Moon and Venus rose over the Peloncillo Mountains of New Mexico. Comet Catalina is in this scene but barely visible.

The Moon, Venus and Comet Catalina
This is a stack of 6 exposures: 30, 8, 2, 0.5, 1/8s and 1/30s, blended with luminosity masks as HDR would not blend images with such a large range of brightness and content, with the shortest exposures having almost no content execept for two bright objects! The camera was on the iOptron Sky-Tracker to follow the sky and keep the sky targets stationary and aligned. All with the 135mm lens at f/2.8 and Canon 6D at ISO 800.

An hour or so later, with the Moon and Venus higher and with skies a little less cloudy, I was able to capture this scene, above, that included Comet Catalina, as a tiny blue dot next to Venus and the Moon. But if I hadn’t labeled it, you wouldn’t know it was there! The comet is proving to be less wonderful than anticipated, and any cloud dims the view even more.

I had hoped for a superb scene of a bright comet next to the two brightest objects in the night sky. But comets do what comets do — surprise people with unexpected brightness (as Comet Lovejoy did last January) or with disappointing dimness … or by disappearing altogether, as Comet ISON did two years ago. I came here in December 2013, to this same location on the Arizona-New Mexico border, to catch ISON but no luck there at all!

Moon & Venus Conjunction at Sunrise (Dec 7, 2015)
This is a stack of 7 exposures from 10 seconds to 0.3 seconds at 1 stop intervals and blended with luminosity masks, to compress the huge range in brightness from the bright Moon and Venus, plus horizon sky, and the darker sky and sunrise clouds. All with the 35mm lens and Canon 6D.

Regardless of the comet, the conjunction of the Moon and Venus was stunning, about as good as such events get. Here’s the view, above, an hour later again, with the eastern sky brightening in the dawn twilight. The only thing that would have made this event even more spectacular is if the Moon had actually covered up Venus in this twilight sky. Not quite.

Daytime Occultation of Venus (Dec 7, 2015)
The occultation of Venus by the waning crescent Moon in the daytime on Monday, December 7 at 9:30 am local time. This is just about 3 minutes before the actual occultation as the advancing Moon is about to cover Venus on the bright limb of the Moon. This is a frame from a 100-frame time lapse. Unfortunately, as I shot this on my trip to Arizona, I did not have more focal length than the 135mm and 1.4x extender used here.

For the occultation itself, we had to wait until well after sunrise for an event in the blue daytime sky, at 9:30 a.m. local time.

All of North America got to see this fairly rare occultation of Venus by the Moon, albeit in the daytime. Nevertheless, the two objects are so bright, this was visible to the unaided eye, even with some cloud about. In binoculars it was wonderful.

To shoot it, all I had was a telephoto lens, so the image scale doesn’t do the event justice. But the image above provides a good impression of the binocular view, with Venus as a brilliant jewel on the “ring” of the Moon.

— Alan, December 7, 2015 / © 2015 Alan Dyer / www.amazingsky.com

Capturing Comet Catalina


Comet Catalina with Venus at Dawn

I got the comet but it isn’t what was hoped for – a faint fuzzball in binoculars.

This was Comet Catalina (aka C/2013 US10) in the dawn sky this morning, December 6, with the comet appearing as a fuzzy star below brilliant Venus in binoculars, and just revealing its two short tails in photos. It’s the cyan-colored object near the centre. Venus is the brilliant object.

This image is with a telephoto lens, and covers a little more of the sky than typical binoculars would show. I knew this would be a binocular comet at best, but it’s barely that. This is more a comet for telescopes.

But as the Moon departs the scene and the comet climbs higher the view may improve. Still, if you are pining for views of Comet Catalina and are stuck under cloudy winter skies at home, don’t be worried. You aren’t missing too much. Except …

Arch of the Autumn Milky Way
The arch of the Milky Way in the northern autumn and early winter sky, from Arizona on December 5, 2015. The Milky Way extends from Aquila to the left, in the southwest to Cassiopeia at top right, to Perseus and Auriga at far right, in the northeast. I shot this from the Quailway Cottage near Portal, Arizona, latitude +32° N. The view is looking north toward the celestial pole. Polaris is just right of lower centre. This is a stack of 8 tracked exposures, each 3 minutes at f/2.8 with the 15mm lens and Canon 6D at ISO 1600, with the ground coming from one exposure to minimize blurring. The camera was on the iOptron Sky-Tracker.

This was the view of the autumn Milky Way from here in Arizona last night. Pretty impressive under nearly perfect sky conditions. And then there’s this …

Winter Sky Setting over the Chiricahuas
Orion and the northern winter constellations and Milky Way setting at dawn over the Chiricahua Mountains of southwest Arizona, near Portal, AZ. The waning crescent Moon in the west provided the illumination in this dawn shot from December 6, 2015. Orion is just above the main peak at centre, with Sirius, in Canis Major, to the left and Aldebaran, in Taurus, to the right. The Pleiades are setting at right. The star cluster at top is the Beehive, M44, in Cancer. Bands of airglow add the red streaks. The site is the Quailway Cottage near Portal, Arizona. This is a stack of 4 x 2 minute exposures, tracked, at f/3.5 with the 15mm full-frame fish-eye lens and Canon 6D at ISO 1250, for the sky, and the same specs for 4 exposures, untracked for the ground. Each set was mean-combined stacked to reduce noise.

This was the winter Milky Way with Orion setting into the west over the Chiricahuas at dawn. Turn around from looking at the comet and this was the view. So who cares if the comet isn’t too great? There’s lots more to see and shoot. With no snow, no frost, no dew.

More to come this week I trust!

— Alan, December 6, 2015 / © 2015 Alan Dyer / www.amazingsky.com

Heads Up! – A Comet in the December Dawn


Dec 7 Venus & Moon

A new comet is coming into our morning sky, for our binocular viewing pleasure.

Comet Catalina, aka C/2013 US10, has emerged from behind the Sun and is beginning to rise into our northern hemisphere dawn sky. The new comet promises to be visible in binoculars, but likely won’t be obvious to the unaided eyes.

On the morning of December 7 the comet sits within a binocular field of the waning crescent Moon which itself sits just above brilliant Venus. That in itself will be a remarkable view, best appreciated in binoculars, and a fine photogenic sight for the camera.

The close conjunction of the crescent Moon with Venus alone will be enough of an attraction on December 7, but the comet should add to the scene.

December 7 Venus Occultation

Even more, later in the day the Moon actually passes in front of, or “occults,” Venus in the daytime sky for most of North America.

That occultation happens in the morning for western North America and in the early afternoon for eastern North America. However, you’ll need a telescope to see it well, and very clear blue skies.

Stellarium Occultation

Use planetarium software (the free Stellarium program, for example, shown above, if you do not own astronomy software) to simulate the sky and provide the occultation times for your location. Zoom into the Moon and run time back and forth on December 7 to see when Venus goes behind the Moon and reappears. The screen shot above is for Calgary.

Back to the Comet

Comet Catalina was discovered in October 2013 at the Catalina Observatory in Arizona. The comet spent the last few months in the southern hemisphere sky, but is now coming north and into our sky, but at dawn.

Comet Catalina Path

It rises higher and higher each morning  through December and into the new year. It may remain at fifth magnitude, bright enough to be easily visible in binoculars from a dark site, but likely not naked eye.

The chart above plots the comet at daily intervals, from December 4 to January 1. The comet is shown for December 15. Note that on the morning of January 1 it sits within a telescope field of the bright star Arcturus.

The distance from Earth to the comet decreases through December and early January, keeping the comet at a constant brightness even as it recedes from the Sun. We are closest to Catalina on January 17, at a far distance of 108 million km. But in late January the comet fades rapidly to become a telescope target.

To see Comet Catalina this month, get up 1 to 2 hours before sunrise and look southeast to east. But you will need dark skies to see it well. This will not be a good urban comet.

Nevertheless, as far as we know, this will be the best comet of 2016.

— Alan, December 2, 2015 / © 2015 Alan Dyer / www.amazingsky.com

 

Last of the Summer Milky Way


Last of the Summer Milky Way

The summer Milky Way sets into the southwest on a late November night. 

On Saturday, November 28, well into winter here in Alberta, the stars of the Summer Triangle and the summer Milky Way set into the southwest on a clear, though slightly hazy, late November night.

This is the last of the summer Milky Way, with the centre of the Galaxy now long gone, but the Summer Triangle stars remaining in the evening sky well into autumn. Glows from light pollution in the west light the horizon, in a quick series of images shot in my rural backyard.

In the Summer Triangle, Vega is at right, as the brightest star; Deneb is above centre, and Altair is below centre, farthest south in the Milky Way.

I shot this as a test image for the Nikkor 14-24mm lens, here wide-open at f/2.8 and at 14mm, where it performs beautifully, with very tight star images to the corners. It does very well at 24mm, too! This is astonishing performance for a zoom lens. It matches or beats many “prime” lenses for quality.

The camera was the 36-megapixel Nikon D810a, Nikon’s “astronomical DSLR” camera, also on test. Here it shows its stuff by picking up the red nebulas in Cygnus and Cepheus.

Thorough tests of both the camera and lens will appear later in the year. Stay tuned.

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For the even more technically-minded, this image is a stack, mean combined, of five 2-minute tracked exposures, at f/2.8 and ISO 800. The camera was on the iOptron Sky-Tracker. So the stars are not trailed but the ground is! I made no attempt here to layer in an untracked ground shot, as there isn’t much detail of interest worth showing, quite frankly.

At least not in the ground. But the Milky Way is always photogenic.

– Alan, November 28, 2015 / © 2015 Alan Dyer / www.amazingsky.com

 

Orion Star Trails in the Moonlight


Orion Rising in the Moonlight

Orion ascends into the sky on a clear autumn night, with its stars drawing trails behind it as it rises.

Only on November nights is it possible to capture Orion rising in the evening sky. Here, I used the light of the waxing gibbous Moon to illuminate the landscape … and the sky, creating the deep blue tint.

The lead image above is an example of a star trail, a long exposure that uses Earth’s rotation to turn the stars into streaks across the sky. In the old days of film you would create such an exposure by opening the shutter for an hour or more and hoping for the best.

Today, with digital cameras, the usual method is to shoot lots of short exposures, perhaps no more than 20 to 40 seconds each in rapid succession. You then stack them later in Photoshop or other specialized software to create the digital equivalent of a single long exposure.

The image above is a stack of 350 images taken over 2.5 hours.

With a folder of such images, you can either stack them to create a single image, such as above, or string them together in time to create a time-lapse of the stars moving across the sky. The short video below shows the result. Enlarge the screen and click HD for the best quality.

 

For the still image and time-lapse, I used the Advanced Stacker Plus actions from StarCircleAcademy to do the stacking in Photoshop and create the tapering star trail effect. A separate exposure after the main trail set added the point-like stars at the end of the trails.


 

My tutorial on Vimeo provides all the details on how to shoot, then stack, such a star trail image…


 

… While this video illustrates how to capture and process nightscapes shot under the light of the Moon.

 

Enjoy the videos! And happy trails!

— Alan, November 24, 2015 / © 2015 Alan Dyer / www.amazingsky.com