The class of objects known as planetary nebulae were originally given that name because they are kind of round like a planet, but we now know that the similarity ends there. A planetary nebula is part of the end stage of a medium sized - like the Sun - star's life. As the star exhausts its fuel, its core collapses becoming an extremely hot, dense white dwarf. At the same time, the outer layers are expelled and illuminated by the remaining white dwarf. That light is so energetic that all the elements found in the nebula (hydrogen, helium, carbon, nitrogen, oxygen and others) shine but the light from oxygen dominates giving the nebula its characteristic blue-greenish color. Farther out, the light from hydrogen begins to dominate giving those regions a reddish color of an emission nebulae.

Descriptive information was drawn from The Sky Atlas 2000.0, 2nd Edition by R. A. Strong and R. W. Sinnott with descriptions by W. Tirion and R. W. Sinnott (2000, Sky Publishing Corp. and Cambridge University Press), and Burnham's Celestial Handbook by Robert Burnham, Jr. (1978, Dover Publications, Inc.). North is up and east to the left in all photos. Every effort has been made to display all photos at the same magnification unless otherwise stated.

NGC 2392 7h 29.2m +20° 55´ Gemini 9.2 Sky Atlas 2000.0
chart 5

NGC 2392 2009-11-28

NGC 2392 – Eskimo Nebula – Clown Face Nebula – Caldwell 39

2009-11-28
White balance = 6000K (Cloudy)
Noise reduction = Off
positive projection 8.5 cm with 25 mm eyepiece (195.1×)
Note: the scale of this photo is approximtely 4.7× most others.
Created from the seventy-one best 30 s - ISO 1600 photos. I removed a dark frame and flat flat field from each photo, then enhance the contrast. I averged these in groups of 8, 9, 9, 9, 9, 8, 9 and 10 and applied a (5.0, 1.0, 0.0) unsharp mask. Next, I averaged the groups, applied a 7×7 Gaussian blur and removed a residual background. Finally, I rotated to north-up, cropped the photo and reduced its size by a factor of four.

This planetary has an inner shell about 10" across clearly visible in this photo, but no detail is evident. A fainter, outer shell, about 20" across, is also visible as are some of the brighter regions in this shell. It is this outer shell that gives NGC 2392 a face-like appearance mentioned by many observers. NGC 2392 is 2,900 l.y. distant. FYI, this object was literally the first thing I observed with my Celestron NexStar 5 and I've developed a great fondness for this object.



NGC 3242 10h 24.8m -18° 38´ Hydra 7.8 Sky Atlas 2000.0
chart 20

NGC 3242 2010-05-04

NGC 3242 – Ghost of Jupiter – Eye Nebula – Caldwell 59

2010-05-04
White balance = 6000K (Cloudy)
Noise reduction = Off
prime focus (51.2×)
Created from one hundred, two 10 s - ISO 1600 photos. I removed a dark frame and flat field from each photo, then enhanced the contrast. I averaged these in groups of six and then averaged those resulting images together. Finally I removed a residual background, cropped the photo and reduced its size by five. Placing the cursor over the photo zooms into full scale. Click the photo to display a larger image in a new window.

This planetary's outer shell is approximately 40" × 35" across. Inside this is a brighter, more elongated shell about half the size of the outer shell making the whole look something like an eye. The inner shell is clearly visible in this photo showing some of its structure. The outer shell is just becoming visible. NGC 3242 is 2,600 l.y. distant.



M97 11h 14.8m +55° 01´ Ursa Major 9.9 Sky Atlas 2000.0
chart 2, 6

M97 2010-05-06

M97 – NGC 3587 – Owl Nebula

2010-05-06
White balance = 6000K (Cloudy)
Noise reduction = Off
prime focus (51.2×)
Created from one hundred, seventy-two 20 s - ISO 1600 photos. I removed a dark frame and flat field from each photo, then enhanced the contrast. I averaged these in groups of forty-three and removed a residual background. I averaged these four super-groups together, applied a 5×5 Gaussian blur, rotated to north-up, cropped the photo and reduced its size by five. Click the photo to display a larger image in a new window.

M97 is an intriguing object. It's close (only 1,300 l.y.), it's young (about 6,000 years) and it's symmetrical splotches (at the 1 o'clock and 7 o'clock positions) remind one of the large eyes of an owl. The current model for M97 describes it as having a barrel-like shape. We happen to be looking through the barrel, but a little off center. The body of the barrel is the gas of the planetary nebula with the “holes” at either end creating the dimmer areas. The magnitude 16 central star of this planetary is visible. Méchain discovered this object in the late eighteenth century, but Lord Rosse appears to be the first to call it the Owl Nebula almost seventy years later.

This was a challenging object for me. I can't “see” the object in a single photo because of the urban sky-glow. After several failed attempts to photograph M97, I drew a picture of its surrounding star-field as it would appear in my telescope and finally found a match.



NGC 6543 17h 58.6m +66° 38´ Draco 8.1 Sky Atlas 2000.0
chart 3

NGC 6543 2009-08-30

NGC 6543 – Cat's Eye Nebula – Caldwell 6

2009-08-30
White balance = 6000K (Cloudy)
Noise reduction = Off
negative project at 12.5 cm (325×)
Note: the scale of this photo is approximtely 6× most others.
Created from the eighteen best 60 s - ISO 800 photos. I removed a dark frame and flat field, then enhanced the contrast for each photo. I averaged the modified photos in three groups of six and enhanced the contrast again. I averaged the three groups, applied a 7×7 Gaussian blur, rotated to north up, cropped and scaled the image by a factor of 3.2.

Moderately sized and relatively bright, this planetary is a good challenge for beginners and smaller telescopes. The inner shell is approximately 20" across but appears slightly elongated with a brigther center reminding one of the slitted pupil of a cat. Unfortunately, NGC 6543's true structure is only hinted at in this photo. NGC 6543 is 3,600 l.y. distant.



M57 18h 53.6m +33° 02´ Lyra 9.0 Sky Atlas 2000.0
chart 8

M57 2009-07-31

NGC 6720 – Ring Nebula

White balance = 6000K (Cloudy)
Noise reduction = Off
prime focus (81.2×)
Created from the sixty best 30 s - ISO 800 photos. I removed a dark frame and flat field from each photo and enhanced the contrast. The modified photos were then averaged six groups of ten, the contrast was enhanced and a residual background removed. I averaged the combined images, applied a 5×5 Gaussian blur, enhanced the contrast, rotated, cropped and reduced the image by 26.8%. This implies a 2× effective magnification relative to the other images shown here. Click the photo to display a larger image in a new window.

At least in my mind, this is the definitive planetary although, truthfully, on-going research has shown that a bipolar shape is more common for planetary nebulae. The outer shell of M57 is approximately 80" × 60" across and lies between 1,400 to 2,000 l.y. distant. A beautiful, relatively easy to find and easy to see object for small telescopes. Note that the star just outside of and to the east (left) of the ring is 13.2 magnitude. The central star is magnitude 15.2.



NGC 6826 19h 44.8m 50° 31´ Cygnus 8.8 Sky Atlas 2000.0
chart 3, 8, 9

NGC 6826 2009-09-27

NGC 6826 – Blinking Planetary – Caldwell 15

2009-09-27
White balance = 6000K (Cloudy)
Noise reduction = Off
negative project at 12.5 cm with reducer/corrector (205×)
Note: the scale of this photo is approximtely 4× most others.
This is composed of the eighteen best 30 s - ISO 800 photos. I removed a flat field and dark frame, and enhanced the contrast in each photo. I averaged the modified photos in groups of six and enhanced the contrast again. Finally, I averaged the groups, enhanced the contrast, applied a 7×7 Gaussian blur, removed a residual background, rotated to north up, cropped and scaled the photo by a factor of 2.

In the telescope, if one looks at the central star of this planetary, the nebula seems to disappear; look off to the side and it "blinks" back into view. Actually, this effect is not uncommon. Our retinas have higher resolution near their centers at the expense of light sensitivity, the outer portions are the reverse. So it is a common "trick" to look just to the side of an object, when looking through a telescope, to glimpse the object's fainter aspects. This is called "averted vision."

Note that NGC 6826 shows some structure. Not unusual at all, but it gives each planetary a unique character, and emphasizes the often dramatic end of a star's normal life. NGC 6826 is about 3,300 l.y. distant with a diameter of 25".


M27 19h 59.6m +22° 43´ Vulpecula 8.1 Sky Atlas 2000.0
charts 8, 9

M27 2009-07-18

NGC 6853 – Dumbbell Nebula – Hourglass Nebula

2009-07-18
White balance = 6000K (Cloudy)
Noise reduction = Off
prime focus using a reducer-corrector lens (52.4×)
Created from the sixty-seven best 30 s - ISO 800 photos. I removed a dark frame and flat field from each photo and enhanced the contrast. The modified photos were then averaged them in five groups of seven plus four groups of eight, and enhanced the contrast. I averaged the combined images, removed a background, and strongly enhanced the contrast. Finlly, I applied a 7×7 Gaussian blur, rotated to north-up, cropped and reduced the image by a factor of five. Click the photo to display a larger image in a new window.

The Dumbbell is the first object of this class ever observed (Messier 1764) and one of the favorites of all amateurs. It is 480" × 240" in size making it possible to spot this object with binoculars from a dark site. although its distance is uncertain, recent values tend to be in the 800 to 1,000 l.y. range. Note the blue speck in the center of the nebula. I believe this is the 13.9 magnitude central star.

Paired with the nearby M57, the Ring Nebula, we have examples of the two classic shapes of planetary nebulae, bipolar (M27) and spherical (M57). It turns out that the M57 is the oddball with many more planetaries having a bipolar morphology.



NGC 7009 21h 04.2m -11° 22´ Aquarius 8.0 Sky Atlas 2000.0
chart 16

NGC 7009 2009-09-27

NGC 7009 – Ghost of Saturn Nebula – Caldwell 55

2009-09-27
White balance = 6000K (Cloudy)
Noise reduction = Off
negative project at 12.5 cm with reducer/corrector (205×)
Note: the scale of this photo is approximtely 4× most others.
This is composed of the forty-two best 30 s - ISO 800 photos. I removed a flat field and dark frame, and enhanced the contrast in each photo. I averaged the modified photos in groups of six and enhanced the contrast again. Finally, I averaged the groups, enhanced the contrast, applied a 7×7 Gaussian blur, removed a residual background, cropped and scaled the photo by a factor of 2.

This planetary came to have the name "Saturn Nebula" because of its unusual shape: kind of squashed north-south, as you can see in the photo, with thin protrusions, not seen here, extending from the ends of brighter, inner portion. Together, it reminds one of the planet Saturn. NGC 7009 is 2,900 l.y. distant and 28" in diameter.



NGC 7662 23h 25.9m +42° 33´ Andromeda 8.3 Sky Atlas 2000.0
chart 9

NGC 7662 2009-11-28

NGC 7662 – Blue Snowball – Caldwell 22

2009-11-28
White balance = 6000K (Cloudy)
Noise reduction = Off
positive projection 8.5 cm with 25 mm eyepiece (195.1×)
Note: the scale of this photo is approximtely 7.6× most others.
Created from the sixty-five best 30 s - ISO 1600 photos. I removed a dark frame and flat flat field from each photo, then enhance the contrast. I averged these in groups of 11, 11, 11, 11, 11 and 10 and applied a (5.0, 1.0, 0.0) unsharp mask. Next, I averaged the groups, applied a 7×7 Gaussian blur and removed a residual background. Finally, I rotated to north-up, cropped the photo and reduced its size by a factor of four.

It's easy to see why this planetary nebula is called the "Blue Snowball". NGC 7662 has at least two concentric shells of gas which are just becoming obvious in this photo. It is estimated to be 3,900 l.y. distant and is 17" in diameter.




Last modified: 2010-05-10