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Old 20-12-2015, 10:35 AM
N1 (Mirko)
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Horsehead & Homunculus

Tahmoor, 20 December 2015, 3.00-4.30 AEDT

No cloud
Transparency 8/10
Seeing 6-7/10

10" f/5 GSO dobsonian
Got up out of bed for this, so dark adaptation was as good as it gets.

IC 434/ B33 Horsehead Nebula, Orion
First observation where I can comfortably say that I saw it. 16mm ES 68° with Astronomik H-Beta filter attached, giving 78x and 3.2mm of exit pupil diameter. Found the general area from memory (not difficult) but because I had not remembered the exact position of B33 relative to the foreground stars, there was absolutely no doubt of its visibility when I saw it. Tube nudging improved view but was not essential.

B33 was not visible without the H Beta, however the Flame Nebula (NGC 2024) was seen very well with its branching dark lane a notable feature.

NGC 3372, specifically the Homunculus Nebula, Carina
The two spheres were seen surprisingly well given the less-than-perfect seeing. Pentax XO5, giving 250x and 1mm of exit pupil diameter. A surpirising amount of detail in the greater Carina Nebula even at this small exit pupil.

This was worth getting up for.
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Old 21-12-2015, 01:49 PM
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Paddy (Patrick)
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Very impressive to see the Horsehead in a 10" scope - well done!!
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Old 02-02-2016, 07:21 AM
N1 (Mirko)
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Dunedin, 1 & 2 February 2016, 22.30 - 1.30 NZDT, about 40km west of the city.

No cloud
Transparency 8/10 in light westerlies. Altitude about 500m.
Seeing 6/10

8" f/6 GSO dobsonian
2.4" FS60C f/5.9

IC 434/ B33 Horsehead Nebula, Orion
Detected as a dark notch in IC 434 sans filter using the 8" while in search mode with OTA moving. So it is possible. 25mm Carl Zeiss PL. Exit pupil 4.2mm. Best view through H beta was obtained with a 32mm TV PL at 5.3mm exit pupil, B33's orientation remaining just beyond reach. However the part of IC 434 immediately to the north of B33 was visibly brighter. So that's something to take home. Patrick, the limits imposed by B33 appear to be related to its angular size. Maintain a large exit pupil and even smaller apertures should show it (I'm confident of that now) - until the magnification used is too low. The 32 PL provides 37x in my 8", which is not that much and the lowest power I've used on this object yet. The Horsehead is of a decent size.

N3372 Eta Carinae Nebula & N3532 Football Cluster
24 Pan & FS60C at 4.1mm exit pupil provided the most epic view of the night with both these objects in the same field. After spending much time looking at marginal shades of dark grey, I looked at this vista and found myself just about launched into space.

Large Magellanic Cloud & Tarantula Nebula
28 Edmund RKE & FS60C is a unique experience. With the OTA being small, the entire telescope disappears behind the "floating eyepiece" when used in straight tru mode. The result is a seamless transition between the image and the surrounding sky. The LMC magnified right next to the Milky Way in the same view!

Messier 42 Orion Nebula
Interesting side observation using the 8" with twilight still in progress: the 13mm TV PL smoothie appears to outperform the 13T6 Nag on Trapezium F. The star was immediately and steadily visible in the PL, took a bit more effort in the Nagler.

Last edited by N1; 02-02-2016 at 07:53 AM.
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Old 06-02-2016, 08:22 PM
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Great obs! The Homunculus is a very unique object. Unlike any other nebula I can think of, it appears sharply defined with hard edged detail much like a solar system onject rather than the soft detail typically found in nebulosity.

Interesting obs between the Plossl and Nagler, perhaps the fewer elements in the plossl result in less light scatter offering a subtly cleaner view?
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Old 08-02-2016, 10:26 AM
N1 (Mirko)
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Quote:
Originally Posted by pgc hunter View Post
Great obs! The Homunculus is a very unique object. Unlike any other nebula I can think of, it appears sharply defined with hard edged detail much like a solar system onject rather than the soft detail typically found in nebulosity.

Interesting obs between the Plossl and Nagler, perhaps the fewer elements in the plossl result in less light scatter offering a subtly cleaner view?
Yes the Homunculus is certainly unique. Perhaps the most foreign looking visual target.

Re plossl, I do suspect it has a bit more throughput as it contains a lot less glass. The image generally looked very clean in both and the view in the 13T6 is still spectacular.
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Old 12-02-2016, 12:23 PM
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Tinderboxsky (Steve)
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IC 434 and B33 in Orion

Following Mirko’s observations and comments using an 8” dob I focused on IC434 with my 140mm refractor at the Ben Lomond Star Party last Saturday night to see what was possible.

Ben Lomond provided clear, dark skies at an altitude of approx 1500 metres
Transparency - 8/10
Seeing - 9/10
Vixen NA140SS with 20mm eyepiece giving 40X with 3.5 mm exit pupil.

Initially, nothing was visible given the dominating glare of Zeta Orion. However, moving Zeta Orion just outside the FOV reduced the glare and made a significant difference.

A faint elongated brighter area, too faint to even be described as a haze, was clearly visible. The position of this brighter area corresponded closely to the location of the brighter eastern side of the emission region. The observation did not require averted vision, nor nudging of the scope. Two other observers sharing the scope at the time had no trouble seeing the same brighter area.

We were content with this observation, noting that there was no prospect of seeing any detail or structure. The Horsehead was clearly out of reach at this aperture.

Cheers

Steve.
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Old 12-02-2016, 01:44 PM
N1 (Mirko)
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Interesting report Steve, and a great scope too. Was this without a filter? I use a 1.25" Astronomik H beta. Impressive, IC434 in direct vision. You were most of the way there. 40x should be enough to see the notch (but not which way he is looking).

What eyepiece did you use? I found modern Abbe orthos ideal for dealing with Alnitak's glare at low power. They might also have a slight edge when it comes to transmission.

Ben Lomond looks like my kind of terrain
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Old 12-02-2016, 02:08 PM
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Tinderboxsky (Steve)
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Thanks for your comments Mirko. Yes, I may have been closer to seeing the notch as you describe it than I thought. With the rush of people wanting to observe I did not have the luxury of some quite time to myself to explore further. Hopefully there will be another opportunity.
I don't have any filters, so none on the night. Eyepiece was a Vixen NLP20. I am still exploring a choice of eyepieces for the NA140.
Yes, Ben Lomond was a good choice for the star party. It is the highest accessible altitude available in Tassie with accommodation. We bunked down in the Northern Tasmanian Alpine Club Lodge. The area is marginally above the snow line with old, underdeveloped ski runs. The ski season is short and fickle.

Steve.
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