Shooting the Heart Nebula


Testing the Nikon D810a

Last night I shot into the autumn Milky Way at the Heart Nebula.

I’m currently just finishing off a month of testing the new Nikon D810a camera, a special high-end DSLR aimed specifically at astrophotographers.

I’ll post a more thorough set of test shots and comparisons in a future blog, but for now here are some shots from the last couple of nights.

Above is the setup I used to shoot the image below, shot in the act of taking the image below!

The Nikon is at the focus of my much-loved TMB 92mm refractor, riding on the Astro-Physics Mach One mount. The mount is being “auto-guided” by the wonderful “just-press-one-button” SG-4 auto-guider from Santa Barbara Instruments. The scope is working at a fast f/4.4 with the help of a field flattener/reducer from Borg/AstroHutech.

I shot a set of 15 five-minute exposures at ISO 1600 and stacked, aligned and averaged them (using mean stack mode) in Photoshop. I explain the process in my workshops, but there’s also a Ten Steps page at my website with my deep-sky workflow outlined.

IC 1805 Heart Nebula (92mm D810a)
The Heart Nebula, IC 1805, in Cassiopeia, with nebula NGC 896 at upper right and star cluster NGC 1027 at left of centre. This is a stack of 15 x 5-minute exposures with the Nikon D810a as part of testing, at ISO 1600, and with the TMB 92mm apo refractor at f/4.4 with the Borg 0.85x field flattener. Taken from home Nov 29, 2015.

The main advantage of Nikon’s special “a” version of the D810 is its extended red sensitivity for a capturing just such objects in the Milky Way, nebulas which shine primarily in the deep red “H-alpha” wavelength emitted by hydrogen.

It works very well! And the D810a’s 36 megapixels really do resolve better detail, something you appreciate in wide-angle shots like this one, below, of the autumn Milky Way.

It’s taken with the equally superb 14-24mm f/2.8 Nikkor zoom lens. Normally, you would never use a zoom lens for such a demanding subject as stars, but the 14-24mm is stunning, matching or beating the performance of many “prime” lenses.

The Autumn Milky Way (Perseus to Cygnus)
The Milky Way from Perseus, at left, to Cygnus, at right, with Cassiopeia (the “W”) and Cepheus at centre. Dotted along the Milky Way are various red H-alpha regions of glowing hydrogen. The Andromeda Galaxy, M31, is at botton. The Double Cluster star cluster is left of centre. Deneb is the bright star at far right, while Mirfak, the brightest star in Perseus, is at far left. The Funnel Nebula, aka LeGentil 3, is the darkest dark nebula left of Deneb. This is a stack of 4 x 1-minute exposures at f/2.8 with the Nikkor 14-24mm lens wide open, and at 24mm, and with the Nikon D810a red-sensitive DSLR, at ISO 1600. Shot from home, with the camera on the iOptron Sky-Tracker.

The D810a’s extended red end helps reveal the nebulas along the Milky Way. The Heart Nebula, captured in the close-up at top, is just left of centre here, left of the “W” forming Cassiopeia.

The Nikon D810a is a superb camera, with low noise, high-resolution, and features of value to astrophotographers. Kudos to Nikon for serving our market!

– Alan, November 30, 2015 / © 2015 Alan Dyer / www.amazingsky.com

 

A Cosmic Christmas Wreath


IC 1396 & Garnet Star in Cepheus

A cosmic Christmas wreath glows in the sky, adorned by a celestial garnet.

This nebula, known as IC 1396, shines in the constellation of Cepheus the king, now high overhead on early winter evenings in the northern hemisphere. It’s a bubble of gas blown by new stars amid the interstellar wreath.

At top, shining like a Christmas light on the wreath, is an orange star. This is Mu Cephei, also known as the Garnet Star. It’s a red supergiant, roughly 1,500 times bigger than our Sun. If it replaced our Sun at the centre of our solar system it would engulf all the planets out to and including Jupiter.

Be happy Mu sits 1,000 light years away!

Happy holidays! And happy solstice. Winter arrives in the northern hemisphere at 6:03 p.m. EST on Sunday, December 21. That’s the shortest day and longest night of the year, for all those north of the equator.

– Alan, December 20, 2014 / © 2014 Alan Dyer

The Head of the Celestial Scorpion


 

Scorpius Head & Antares (135mm 5DII) v2The head of Scorpius is laced with colourful nebulas, both bright and dark. 

This is an image from two nights ago, from the dark skies of southeast Arizona. It takes in the head of Scorpius, from yellow Antares at lower left as the heart of the Scorpion, to the blue stars at right that mark his head.

The remarkable feature of this region of sky is its colour. No where else in the sky do we see (or I should say, does the camera see) such a spectrum of colourful nebulas. Dark brown lanes run down from the constellation Ophiuchus at left. They meet up with a yellow patch of nebulosity caused by dust reflecting the yellow-orange light of the giant star Antares.

Hot blue stars light up other dusty patches, while the magenta nebulas are created by gas emitting light, not just reflecting light from nearby stars.

A close-up of the region, shot in Australia last month, appears in my blog post from April 17, Stars Scenes in Scorpius. The image above, shot with a 135mm telephoto lens, takes in an area of sky that typical binoculars would frame.

But the eye sees only a hint of the detail, and none of the colour, hidden in the heart of Scorpius.

– Alan, May 6, 2014 / © 2014 Alan Dyer

 

Stellar Graveyard in Vela


Vela Supernova Remnant (77mm 5DII)

This is what’s left of a star that exploded in ancient times.

This is the Vela Supernova Remnant, an object in the southern sky in the constellation of Vela the Sail. The wispy tendrils of magenta and cyan are all that’s left of the outer layers of giant star that exploded about 12,000 years ago.

Cluttering the field at left are amorphous patches of star-forming nebulosity that are part of the much larger Gum Nebula complex.

The supernova was only about 800 light years away so it would have been a brilliant sight in the sky to neolithic observers, far outshining any other stars. But no record exists of anyone seeing it.

The star didn’t destroy itself completely – its core collapsed to form a pulsar, an ultra-dense ball of neutrons, in this case spinning about 11 times a second. The pulsar is in this field but it’s much too faint to show up in visible light.

I shot this earlier this month from Australia where Vela sails directly overhead. The field is about 6° by 4°, the amount of sky framed by high power binoculars. The brighter parts of the Vela Remnant can be picked out in large amateur telescopes – I’ve seen bits of it in my 10-inch telescope – but this is certainly a challenging object to see, even with aided eyes.

— Alan, April 23, 2014 / © 2014 Alan Dyer

 

 

Star Scenes in Scorpius


Scorpius Overhead (50mm 5DII)

Scorpius, one of the most photogenic of constellations, contains a wealth of amazing sky sights.

My trip to the land down under is coming to an end but I’m still working through the dozens of deep-sky images I was able to take under the southern stars. The wide-field scene above takes in all of Scorpius, shot with the constellation sitting directly overhead in the pre-dawn hours of an austral autumn. You can trace the scorpion’s winding shape down from his head and claws at top, to his curving stinger tail at bottom.

M6 and M7 Star Clusters in Scorpius (77mm 5DII)

Off the stinger of the scorpion shine two naked-eye star clusters, Messier 6 and 7 (the close-up photo above). M6 is the Butterfly Cluster, seen here sitting in a dark region of the Milky Way at upper right. Its companion, M7, a.k.a. Ptolemy’s Cluster at left of the frame, is lost amid the bright star fields  that mark the direction of the galactic core.

NGC 6334 Cat's Paw Nebula (77mm 5DII)

In the curving tail of the scorpion lie two patches of nebulosity. At upper left is NGC 6357, but the triple-lobed NGC 6334 at bottom right is also known as the Cat’s Paw Nebula.

False Comet NGC 6231 Area (77mm 5DII)

Further up the tail of the scorpion sits this fabulous region of space that is a stunning sight in binoculars. NGC 6231 is the blue star cluster at bottom, which garnered the name The False Comet Cluster back in early 1986 when many people mistook its fuzzy naked eye glow for Comet Halley then passing through the area. The camera reveals the region filled with glowing hydrogen gas.

Antares & Rho Ophiuchi Area (77mm 5DII)

But the standout region of Scorpius lies at its heart. Here, the yellow-orange star Antares lights up a dusty nebula surrounding it, reflecting its yellow glow. At top, another dusty nebula surrounds the star Rho Ophiuchi, reflecting its blue light. Glowing hydrogen gas adds its characteristic magenta tints. This is one of the most colourful regions of the Milky Way.

I shot these images with 50mm normal and 300mm telephoto lenses two weeks ago during the OzSky Star Safari near Coonabarabran, NSW, Australia. For all I used a filter-modified (by Hutech) Canon 5D Mark II camera.

— Alan, April 17, 2014 / © 2014 Alan Dyer

 

A Star-Filled Scene in Cassiopeia


M52 & NGC 7635 Bubble Nebula (92mm 5DII)

A star cluster and nebulas highlight a glorious starfield in Cassiopeia.

I shot this three nights ago on a very clear autumn evening. The telescope field takes in the star cluster Messier 52 at upper left, a cluster of 200 stars about 5000 light years away. It is one of the best objects of its class for viewing in small telescopes. Charles Messier found it in 1774 as part of his quest to catalog objects that might be mistaken for comets.

The brightest area of nebulosity below M52 is the Bubble Nebula, aka NGC 7635, found in 1787 by William Herschel. It’s an area of star formation marked by a central bubble of gas (just visible on the scale of my photo) being blown by the winds from a hot central star. The Bubble can be seen in amateur telescopes but is a tough target to spot.

Above the Bubble is a small bright nebula, NGC 7538.

Below the Bubble lies a larger claw-like nebula known only as Sharpless 2-157, an object that shows up only in photos.

In all, it’s a complex and beautiful field, set in the constellation of Cassiopeia the Queen.

A footnote for the technically minded: This is a stack of 5 x 15 minute exposures with a filter-modified Canon 5D MkII at ISO 800 shooting through a TMB 92mm apo refractor at f/4.8, mounted on an Astro-Physics Mach 1 mount guided by a Santa Barbara SG-4 autoguider.

– Alan, October 11, 2013 / © 2013 Alan Dyer

 

The Veil Nebula in Cygnus


NGC 6960 & 6992-5 Veil Nebula (92mm 5DII)

This is what’s left of a star that exploded thousands of years ago.

I shoot this object every year or two, so this is my 2013 take on the Veil Nebula. For last year’s see Star Death Site, a post from September 2012.

The Veil Nebula is a supernova remnant. The lacework arcs are what’s left of a massive star that blew itself to bits in historic times. This object, one of the showpieces of the summer sky for telescope users, is now high overhead at nightfall, off the east wing of Cygnus the swan.

I shot this a couple of nights ago using a 92mm-aperture refractor that provides a wide field of view to easily frame the 3-degree-wide extent of the nebula. The image is a stack of five 15-minute exposures with a filter-modified (i.e. red sensitive) Canon 5D MkII camera at ISO 800. Stacking the images helps reduce noise.

The colours in this object make it particularly photogenic, with a contrast of magenta and cyan. At right, a sharp-edged area of obscuring interstellar dust tints the sky brown and dims the stars.

– Alan, October 9, 2013 / © 2013 Alan Dyer