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Designations:
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M42 and M43, Great Orion Nebula
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Object
Type:
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Constellation:
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Orion
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5 hr 35.6 min
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-5° 16'
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3.7
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Size:
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1.5 ° X 1.0 °
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Distance:
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1,500 light years
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Discoverer:
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Nicholas Peiresc, 1611
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Designations:
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M43, NGC 1982
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Object
Type:
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Constellation:
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Orion
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5 hr 35.6 min
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-5° 16 min
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6.8
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Size:
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20 X 15 arcminutes
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Distance:
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1,500 light years
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Discoverer:
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Jean-Jacques Dortous de Mairan, before 1750
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Designations:
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NGC 1977, Running Man Nebula
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Object
Type:
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Emission and Reflection Nebula
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Constellation:
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Orion
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05 hr 36 min
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-04° 50 min
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7
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Size:
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20 X 10 arcminutes
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Distance:
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1,500 light years
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One of the greatest paradoxes in visual astronomy is that
Galileo (who paid great attention to Orion, according to Webb) apparently never noticed the
Great Nebula. Furthermore, there appears to be no mention of it in medieval records. Yet here
is one of the grandest naked-eye nebulae in the heavens, dangling from one of the best-known
asterisms (Orion's Belt) in one of the most famous and brilliant constellations. That Galileo
would have missed seeing it is especially puzzling given that Al-Sufi and others had noticed
the fainter "nebula" in Andromeda (M31) as early as A.D. 905! Messier also miscredits Huygens
with the discovery of the Orion Nebula, apparently unaware of the earlier observations made by
Peiresc and others. But even Huygens's words should alarm modern day observers: "There is one
phenomenon among the fixed stars worthy of mention, which as far as I know, has hitherto been
unnoticed by no one and indeed, cannot be well observed except with large telescopes."
(Emphasis is mine.) Yet, in how many New England winters have I looked across snow laden
fields to see this nebula, in the middle of Orion's sword, looking like angel's breath against
a frosted sky. Even today, M42 is visible with the naked-eye from the heart of downtown Boston,
Massachusetts. The Orion Nebula is an enormous cloud of fluorescent gas, predominantly hydrogen -
with traces of helium, carbon, nitrogen, and oxygen - 40
light years
in diameter. It glows by the
ultraviolet radiation streaming on Theta (θ) Orionis, a bright grouping of four massive stars, whose
light energy is burning a hole through the mackerel clouds of the nebula's sharply defined interior.
Commonly called the Trapezium, these four jewels shine between 5th and 8th
magnitude,
and it is the
brightest member that produces 99 percent of the energy that illuminates the clouds of gas we see through
our telescopes. All the hot, young Trapezium stars probably began shining a mere 1 million years ago
(our sun is 4.5 billion years old). And there are about a thousand unseen members (300,000 to 1 million
years old) hiding in the dense cloudscapes. Recent Hubble Space Telescope images show the expansive
nebula in unprecedented detail: tumultuous swirls of colorful churning gas; 40-billion-mile-long
"comets" of dust and gas, whose comas enshroud newborn stars; dark protoplanetary disks silhouetted
against the nebulas spectral glow. The HST has confirmed what astronomers have long suspected: M42 has
all the ingredients for solar and planetary creation.
M43 is a wedge of nebulosity surrounding a 7th- magnitude star ( called Bond's star) 10' northeast of the Trapezium. Commonly overlooked because of its proximity and association with the Orion Nebula, M43 harbors a wealth of detail that is well worth becoming acquainted with, so plan an evening with it. You will have to block out the commanding presence of its larger neighbor, but one way to seclude M43 is to use high magnification. See if you can resolve the tiny dark pool due east of Bond's star. One night a short but strong earthquake struck while I was examining M43. The telescope began to shake and, when it did, my eye caught sight of some extremely faint extensions looping to the west and a long wedge of material flowing to the east. Instead of waiting for an earthquake, try tapping your telescope tube and see if you can make out these subtle features. Also, be sure to move north of M43 to NGC 1977, more nebulosity whose wavy texture is delightful at low powers. Then move farther north to the loose open cluster NGC 1981, to complete your tour of Orion's sword. |
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Telescope:
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Focal Length:
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384mm (480 * 0.8x reducer)
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Mount:
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Camera
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Guider:
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Exposures:
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20 30-second exposures and 12 2-minute Hydrogen-Alpha exposures (Luminance) 30 1-minute exposures for each color (Red, Green and Blue)
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Location:
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Cicero, IN
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Software:
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CCDSoft for image acquisition, processed with CCDStack and Photoshop CS2
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