NGC 6960, the Witch's Broom (also Western Veil or Sharpless 103) Nebula is a remnant from a supernova about 10,000 years ago. Its amazing filamentary structure is due to compression of expanding shells of gas as they meet the resistance of the interstellar medium. That much of what we see as "empty" space is filled with dark dust is evidenced by there being more background stars visible below the nebula, where it has swept space clear of dust, than above it. The bright star, 52 Cygni, is a type K star and a foreground object with no physical association with the nebula, but adds to the drama of the image. Please compare this image to my previous image of it taken with my Celestron Compustar C14, shown under Nebulae. The difference in sharpness, clarity, and detail is jaw-dropping.

Telescope/Mount: PlaneWave CDK17 on L500 mount

Exposures: Ha:L:R:G:B = 300:245:95:95:95 minutes = 11 hours, 40 minutes total exposure at f/6.8.

M33 is one of the closest spiral galaxies lying at a distance of 2,723,000. It therefore appears large and also presents us with a nearly face-on view. As such, it reads like an open book on all the processes we can see going on in a spiral galaxy. Dark dust clouds condense into hot blue supergiant stars. They emit intense ultraviolet radiation that strike the remaining hydrogen gas in the cloud and cause it to glow red as an emission nebula at the hydrogen-alpha frequency of 656.28 nm. They also emit fierce stellar winds that drive the gas away and the stars within the nebula become unbound and spread out as an OB association of blue supergiants. But those blue supergiants live fast and die young as supernovae within a few million years. The shockwaves from the supernovae compresses gas in neighboring dark clouds, causing them to collapse and the process repeats. As the galaxy rotates over millions of years, these processes trace out curving spiral arms of blue supergiants ornamented with red emission nebulae. Compare this image with my previous image of M33 taken with the Celestron Compustar C14, shown under Galaxies. The difference in sharpness, clarity, and detail is jaw-dropping.

Telescope/Mount: PlaneWave CDK17 on L500 mount.

Exposures: Ha:L:R:G:B = 480:460:110:110:110 minutes = 21 hours, 10 minutes total exposure at f/6.8/

One can see the entire process of new star formation in this view of the iconic Horsehead Nebula in Orion. The blue supergiants star Sigma Orionis, which is above the field of view, is emitting intense ultraviolet radiation that is ionizing the hydrogen in the emission nebula IC 434, causing it to glow red at a wavelength of 656.28 nm. That star is also emitting fierce stellar winds that are creating wisps and streaks within the nebula and also cause it to pile up as a shock wave as it encounters the resistance of the large dark molecular dust cloud, Lynds Dark Nebula 1630. However, there are some persistent intrusions of the dark nebula into the emission nebula, such as the Horsehead Nebula itself. As the fierces stellar winds continue to apply pressure to the edges of these intrusions, the hydrogen within them becomes compressed and eventually gravity takes over and the hydrogen collapses into a newborn star.

The newborn star will emit its own fierce stellar winds that will drive away the surounding dust and star will emerge from the dark nebula. Because the surrounding dust scatters the light from the star, the surrounding area appears blue, just as Earth’s atmosphere scatters light from the Sun makes the sky appear blue, creating a blue reflection nebula. These processes are visible in the blue reflection nebula NGC 2023 at the bottom left of the image.

Telescope/Mount: PlaneWave CDK17 on L500 mount.

Camera: SBIB STL 11000M with Baader Planetarium Ha, L, R, G, and B filters.

Exposures: Ha:L:R:G:B = 1155:175:85:85:85 minutes = 26 hours, 25 minutes total exposure.

M75 is a globular cluster in Sagittarius lying at a distance of 67,500 light-years. This means when we view M75, we are peering past the south side of the Milky Way galaxy’s core and seeing this globular cluster hovering over the outskirts of the far side of our galaxy’s disk. Harlow Shapley and Helen Sawyer classified globular clusters on a scale of I-XII based on how densely packed they are. Class I globulars are so densely packed as to have unresolvable cores, whereas class XII are so loosely packed as to resemble circular open star clusters. M75 is the only Class I globular in the Messier Catalog and is notorious for being so densely packed as to be unresolvable through even the largest amateur telescopes. However, photographically, the CDK17 resolved the core of this globular cluster spectacularly well.

Telescope/Mount: PlaneWave CDK17 on L500 mount.

Exposures: L:R:G:B = 165:60:60:60 minutes = 5 hours, 40 minutes total exposure at f/6.8.

M79 is a rare wintertime globular cluster in the constellation Lepus, just south of Orion. It is a historically important globular cluster. In 1918, Harlow Shapley calculated the distances to globular clusters and plotted their distribution. They had a spherical distribution around the plane of the Milky Way and there were many in the direction of Sagittarius, some of which he found lay at tremendous distances. However, he found only three in the opposite direction all lying at moderate distances. By correctly assuming that the center of the sphere coincided with the center of the Milky Way, he deduced that we were not at the center of the galaxy, but about half way out toward the edge of the disk, giving us our biggest demotion of position in the universe since Copernicus put the sun at the center of the solar system.

This image was published in the August, 2024 issue of Astronomy magazine.

One can see the entire process of new star formation in this view of the iconic Horsehead Nebula in Orion. The blue supergiants star Sigma Orionis, which is above the field of view, is emitting intense ultraviolet radiation that is ionizing the hydrogen in the emission nebula IC 434, causing it to glow red at a wavelength of 656.28 nm. That star is also emitting fierce stellar winds that are creating wisps and streaks within the nebula and also cause it to pile up as a shock wave as it encounters the resistance of the large dark molecular dust cloud, Lynds Dark Nebula 1630. However, there are some persistent intrusions of the dark nebula into the emission nebula, such as the Horsehead Nebula itself. As the fierces stellar winds continue to apply pressure to the edges of these intrusions, the hydrogen within them becomes compressed and eventually gravity takes over and the hydrogen collapses into a newborn star.

The newborn star will emit its own fierce stellar winds that will drive away the surounding dust and star will emerge from the dark nebula. Because the surrounding dust scatters the light from the star, the surrounding area appears blue, just as Earth’s atmosphere scatters light from the Sun makes the sky appear blue, creating a blue reflection nebula. These processes are visible in the blue reflection nebula NGC 2023 at the bottom left of the image.

This image was shot completely unguided with a total exposure of over 26 hours, which is a testament to the superb tracking accuracy of the L500 mount.

Telescope/Mount: PlaneWave CDK17 on L500 mount.

Camera: SBIB STL 11000M with Baader Planetarium Ha, L, R, G, and B filters.

Exposures: Ha:L:R:G:B = 1155:175:85:85:85 minutes = 26 hours, 25 minutes total exposure.

Sh2-96, also known as LBN066 is an extremely faint emission nebula in Cygnus and rarely imaged. It is known as the Scarlet Letter Nebula, and just like in the novel The Scarlet Letter by Nathaniel Hawthorne, the letter outlined by this nebula is a capital A. The field also abounds with faint hydrogen-alpha nebulosity. The image required more than 21 hours of total exposure time.

Instrument/mount: PlaneWave CDK17 on L-500 mount.

Camera: SBIG STL11000M with Baader Planterium Ha, L, R, G, and B filters, guided.

Messier 81, also known as Bode's Galaxy, is a class Sb spiral galaxy lying 11.7 million light-years from Earth. Despite its classic spiral appearance, it contains hints of a "recent" (in cosmological terms) disruptive interaction with another galaxy: namely, the three parallel, nearly straight dust lanes visible just to the left of the nucleus. The responsible interaction likely occurred with neighboring galaxy Messier 82, the Cigar Galaxy, which came out of the interaction far more disrupted than Messier 81. The irregular dwarf satellite galaxy Holmberg IX is visible to the lower right of Messier 81. It is analogous to one of our Magellanic clouds. 

Telescope/mount: CDK17 on L-500 series moun

Exposures: Ha:L:R:G:B = 135:400:90:90:85 minutes = 13 hours, 20 minutes total exposure, unguided. 

Messier 78 is a blue reflection nebula in Orion. It is located just a bit northeast of the stars in Orion’s belt and lies 1,350 light-years from Earth. M78 is the brightest reflection nebula in the sky and its blue color results from the scattering of light emitted from the bright stars in the nebula, just as how our atmosphere’s scattering of sunlight results in a blue sky. M78 is in the center of the image while blue reflection nebula NGC 2064 is peering out from behind dust above it, NGC 2067 is to its upper left, and NGC 2071 is in the lower left corner. The dark nebulae are part of molecular cloud L1630 in Orion. This region of the sky is rich in Herbig-Haro (HH) objects, newborn stars with bipolar outflows that strike the dark dust and cause it to glow red. HH 24 and HH25 mark the locations of stars just emerging from the dark nebula in the upper right corner. Just above the double star in the upper right is the location of McNeil’s variable nebula. It became invisible in November, 2018 and hasn’t been seen since.

Image Data:

Telescope/mount: CDK17 on L500 mount

Camera: SBIG STL 11000 with Baader Planetarium L,R,G, and B filters.

Exposures: L:R:G:B 235:75:75:75 minutes =7 hours 40 minutes total exposure, all completely unguided.

IC 342 is a face-on classic spiral galaxy in Camelopardalis. It lies near the Milky Way's galactic equator and is therefore found amidst a dense field of colorful Milky Way stars. However, the bigger issue is that it is greatly dimmed by obscuring dark dust in our galaxy rendering it very difficult to image, requiring very long exposure times. This has lead to the intriguing name of "The Hidden Galaxy". It lies only 7 million light-years from Earth and, despite its dim appearance, ranks as the third largest galaxy in the sky in terms of angular dimensions, surpassed only by M31 in Andromeda and M33 in Triangulum. It is rich in dust lanes and HII regions.

Telescope/Mount: PlaneWave CDK17 on L500 mount.

Exposures: Ha:L:R:G:B = 900:520:165:155:155 minutes = 31 hours, 35 minutes total exposure, guided.

NGC 4565 is an edge-on Hubble class Sb galaxy that lies approximately 40 million light-years from Earth. It marks the Milky Way’s north galactic pole, just as Polaris marks the north celestial pole. We view it perpendicular to our galaxy's equatorial dust plane, providing a view virtually unimpeded by dust.  The equatorial dust plane of NGC 4565 is plainly visible and divides the galaxy's central bulge almost equally, with the galaxy's bright nuclear shining just to one side of the dust lane. The spiral galaxy to the upper left is NGC 4562 is to the upper left and galaxy IC 3571 is directly below the core. Multiple distant PGC galaxies are scattered throughout the image.

Telescope/mount: PlaneWave CDK17 on L500.

Exposures: L;R:G:B = 325:120:120:120 minutes = 11 hours, 25 minutes total exposure, completely unguided.

M13 is a Shapley-Sawyer Class V globular cluster lying 25,000 light-years from Earth in the constellation of Hercules. An interesting feature of M13 is the Y-shaped dark lanes in the upper left portion of the cluster. This was first noted by Binden Stoney using Lord Rosse's 72-inch reflector at Birr Castle, Ireland in the 1850s. It is now referred to as "The Propeller" due to its resemblance to a propeller with three blades. It is debated whether the propeller is due to obscuring material in the cluster blocking our view of stars behind it, or due simply to zones with fewer stars. However, it has been known since the early 1960s that globular clusters do contain dark obscuring nebulosity material, so the former theory is favored. The CDK 17 resolved this feature very clearly as well as resolved countless stars in the core of M13. The small galaxy at the upper right is IC 4617, which lies at a distance of 553 million-light years, which gives an incredible depth of field to the image.

Exposures: L:R:G:B = 245:40:40:40 minutes =6 hours, 5 minutes total exposure at f/6.8.

M3 is a Shapley-Sawyer Class VI globular cluster lying at a distance of 33,920 light-years from Earth. The interesting feature in M3 is a meandering dark line crossing the entire cluster. This line gives the globular cluster an appearance resembling a cracked egg. That globular clusters contain dark obscuring nebular material has been known since the early 1960s.

Exposures: L:R:G:B = 170:65:65:65 minutes = 6 hours, 5 minutes total exposure at f/6.8.

M22 is a Shapley-Sawyer Class VII globular cluster lying 9,785 light-years from Earth in Sagittarius. That makes it one of the closest globular clusters. While most globular clusters are found far from the plane of the Milky Way in fields only sparsely populated with stars, M22 lies close to the heart of the Milky Way. Thus, it is a real treat to view it amidst a field of countless colorful Milky Way foreground stars. The considerable amount of galactic dust lying between us and M22 also reddens the cluster, giving it a slightly yellowish tinge.

Exposures: L:R:G:B = 25:25:25:25 minutes = 3 hours, 5 minutes total exposure at f/6.8.

M91 is a rare face-on barred spiral galaxy lying at a distance of 63 million-light years in Canes Venatici. It is part of the Virgo Cluster of galaxies. Overall, it is one of the faintest objects in the Messier Catalog, but its core is thousands of times brighter than its faint spiral arms, so it requires skillful processing to show the spiral arms without blowing out the core and bar.

Exposures: L:R:G:B = 180:80:80:80 minutes = 7 hours total exposure at f/6.8.

M63 is a class SB spiral galaxy in Coma Berenices lying at a distance of 23.9 million light years. Unlike grand design SB spiral galaxies with well-defined spiral arms, M63 is of the rarer "floculent" design with spiral arms that cannot be traced. This design has the characteristic of having a sharp drop off in brightness between the core and the spiral arms, making it difficult for imagers to display both features simultaneously. The sigmoid whisp below the bright star to the right side of the galaxy is irregular galaxy UCGA 342, which appears to be a satellite galaxy of m63, analogous to one of our Magellanic Clouds.

M64 is a type 2 Seyfert galaxy lying at a distance of 17 million light-years from Earth in the constellation Coma Berenices. It is known as "The Black Eye Galaxy" due to its prominent, compact dust lane. The galaxy actually has two disks, a brighter inner one and a dimmer outer one, which are counter rotating relative to each other.

Exposures: L:R:G:B = 170:90:90:90 minutes = 7 hours, 20 minutes total exposure at f/6.8.

NGC 6992, the brightest portion of The Veil Nebula, is the remnant of a supernova that occurred 10-15,000 years ago. Its amazing filamentary structure may be due to compression of expanding shells of gas as they meet the resistance of the interstellar medium. The fact that the nebula is sweeping up interstellar dust as it expands is evidenced by the visibility of more faint stars on the lower right side of the nebula than on the upper left side. Compare this image obtained with the PlaneWave CDK17 and L-500 mount to the image obtained with the Compustar C14, under the heading of Nebulae.

IC 1340, otherwise known as The Bat Nebula and Caldwell 33, is a beautiful portion of the Cygnus loop supernova remnant that reveals delicate wisps and filaments of nebulosity. Sadly, it is often overlooked because of the notoriety of three other portions of the Cygnus loop, namely the Veil Nebula, The Witch's Broom Nebula, and Pickering's Triangle. IC 1340 is the continuation of the Veil Nebula. The nebula lies approximately 1,500 light-years from Earth. Compare this image obtained with the PlaneWave CDK17 and L-500 mount with the image obtained with the Celestron Compustar C14, shown under the heading of Nebulae.

M1, the Crab Nebula in Taurus is a supernova remnant from the supernova recorded by the Chinese as a “Guest Star” in the constellation of the Bull on July 4, `1054. It was visible in daylight for 23 days and visible at night for 653 days. It was also recorded on petroglyphs by indigenous people of southwest North America in 13 different locations. The nebula lies 6,500 light-years from Earth. explosive projections of the supernova are clearly seen in the red hydrogen-alpha components of the image. The nebula now spans 11 light-years, which means the material was ejected at roughly 1% the speed of light.

Exposures: Ha:L:R:G:B =50:50:50:50 minutes = 4 hours, 10 minutes total exposure, completely unguided.

This image shows two interacting galaxies lying 40-50 million light-years away in Canes Ventatici. They are speeding away from each other, separated by 24,000 light-years. Both galaxies are thought to have originally been spirals, now distorted by the tidal forces of the interaction. The larger galaxy, NGC 4490, also known as the Cocoon Galaxy and the smaller galaxy is NGC 4485.

Exposures: Ha:L:R:G:B = 60:105:60:60:60 5 hours, 45 minutes total exposure.

NGC 4725, "The One-Armed Galaxy", is a barred-spiral galaxy lying 40 million light-years from Earth in Coma Berenices. The classic spiral galaxy to its lower right is NGC 4712, which lies 224 million light-years from Earth. Exposures L:R:G:B = 400:70:70:70 minutes = 10 hours, 10 minutes total exposure, completely unguided.

M94, "The Crocodile Eye Galaxy", is an unusual spiral galaxy with a bright nucleus, inner oval region with dust lanes, and faint outer ring with star clouds and dust clouds lying at a distance of 16 million light-years from Earth in the constellation Canes Venatici. It is very difficult to process because the nucleus and inner oval are intensely bright, while the outer ring is exceedingly faint. However, the contribution of the faint outer ring makes it one of the largest galaxies in the sky. Exposures: L:R:G:B =230:125:130:105 minutes = 9 hours, 50 minutes total exposure, completely unguided.