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(IAAC) Obj: The Homunculus (NGC 3372, Eta Car) - Inst: 20" f5 Dobsonian
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Observer: Andrew Murrell
Your skills: Advanced (many years)
Date/time of observation:
Location of site: Ilford NSW Australia (Lat , Elev )
Site classification: Rural
Sky darkness: 6.5 <1-10 Scale (10 best)>
Seeing: 8-9.5 <1-10 Seeing Scale (10 best)>
Moon presence: None - moon not in sky
Instrument: 20" f5 Dobsonian
Magnification: 160-700
Filter(s): none
Object(s): The Homunculus (NGC 3372, Eta Car)
Category: Planetary nebula. Emission nebula.
Class: stellar ejecta
Constellation: carina
Data: mag 6.5 size 30"
Position: RA 10:45.1 DEC -59:41
Description:
The Homunculus is the small nebulae that surrounds Eta Carina. It is the envelope
of stellar material that was ejected from the star about a century ago. This is the
only nebulae that shows an obvious colour, Bright orange. This colour is very
striking against the star background. The initial observation was at 160x. This shows
the surrounding keyhole nebulae NGC3372, which defies description. The Homunculus
appears as a peanut shaped orange blob about 30" across. At 300x it appears as a bright
hazy star with a lobe or bubble of material on either side, orietated SW-NE. The lobe
to the SW is the brightest, and appears granular with a dark lane running throughthe
middle which curls to the southat the end. The NE lobe is fainter and shows no internal detail
The center star is about 6.5 magnitude and has a jet progecting to the north about 5" long.
Averted vision at this power intensifies the colour and shows a bright knot 5" WSW of the star
in the SW lobe. By increasing the magnifaction to 720x even more detail was glimpsed. In moments
of perfect seeing the granulation in the NE lobe became apparent. The bright knot became visible
with direct vision,and the colour remained. The dark lane seen before in the SW lobe lost some of
its structure, looking more difuse and ending in a small dark hole positioned about 5" from the southern
edge of the nebulae. The higher magnifaction increased the contrast. The edge of the nebulae remained
sharp across the entire perimeter and the arm or jet was easily picked up. What became most noticable
about the homunculus was the FAINT halo that surrounded the entire object and doubled its size.
The difuse glow had an indistinct edge and appeared evenly distributed about the object. No intermal
details were seen in this faint envelope
A right angle of 15th magnitude stars are positioned about 15" NW of the central star adding to the
view at this power. As a side note to this observation stars of 4th magnitude and brighter had difraction
rings visible, one complete ring and two partial. The seeing was the best in several years that I had seen
Reducing the magnifaction to 300x I looked for the faint halo but it would not reveal itself, probably due
to the glare from the star and the nebulae.
This goes down as one of the TOP 5 objects in the entire sky.
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