APOD: IC 2118: The Witch Head Nebula (2012 Jan 17)

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APOD: IC 2118: The Witch Head Nebula (2012 Jan 17)

Post by APOD Robot » Tue Jan 17, 2012 5:06 am

Image IC 2118: The Witch Head Nebula

Explanation: Double, double toil and trouble; Fire burn, and cauldron bubble -- maybe Macbeth should have consulted the Witch Head Nebula. This suggestively shaped reflection nebula is associated with the bright star Rigel in the constellation Orion. More formally known as IC 2118, the Witch Head Nebula glows primarily by light reflected from bright star Rigel, located just below the lower edge of the above image. Fine dust in the nebula reflects the light. The blue color is caused not only by Rigel's blue color but because the dust grains reflect blue light more efficiently than red. The same physical process causes Earth's daytime sky to appear blue, although the scatterers in Earth's atmosphere are molecules of nitrogen and oxygen. The nebula lies about 1000 light-years away.

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Re: APOD: IC 2118: The Witch Head Nebula (2012 Jan 17)

Post by Ann » Tue Jan 17, 2012 5:52 am

Double, double toil and trouble - Gimmi Ratto and Davide Bardini had to suffer a lot of toil and trouble to collect enough light to produce this very fine picture of the Witch Head Nebula. Congratulations on having your picture chosen as a well-deserved Astronomy Picture of the Day!

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Re: APOD: IC 2118: The Witch Head Nebula (2012 Jan 17)

Post by Nightfly » Tue Jan 17, 2012 10:41 am

FYI, the date listing here is incorrectly identifying it as Jan 17th 2011 (instead of 2012) http://apod.nasa.gov/apod/
The archive listings show the right 2012 dates but the individual pages for this year are still showing "2011"

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Re: APOD: IC 2118: The Witch Head Nebula (2012 Jan 17)

Post by owlice » Tue Jan 17, 2012 10:57 am

Thanks, Nightfly; the editor has been notified.
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Re: APOD: IC 2118: The Witch Head Nebula (2012 Jan 17)

Post by orin stepanek » Tue Jan 17, 2012 2:00 pm

Very nice! 8-) I also like this one! 8-) http://apod.nasa.gov/apod/ap091229.html
Orin

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Re: APOD: IC 2118: The Witch Head Nebula (2012 Jan 17)

Post by KCM » Tue Jan 17, 2012 2:02 pm

So if the nebula is reflecting blue light, what type of filter would be helpful to observe the Nebula? Or is any necessary?

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Re: APOD: IC 2118: The Witch Head Nebula (2012 Jan 17)

Post by Ann » Tue Jan 17, 2012 5:27 pm

My guess is that this nebula will be very hard to observe.

Since the nebula is a reflection nebula, it reflects much of the light that hits it more or less equally. Admittedly it reflects blue light far better than red light. That still leaves a broad range of wavelengths that are reflected by this nebula. You may try to use an OIII or an H beta filter, which will let through some of the blue-green light from the nebula and block a lot of the background light, but you will still miss a lot of the light from the nebula this way.

A wide wavelength blue filter might be the best, if there are any such filters. But a problem is that many of the stars in the vicinity are blue themselves, and the blue filter will let through most of their light. So the light from the stars will overwhelm the light of the nebula, which is fairly faint anyway.

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Re: APOD: IC 2118: The Witch Head Nebula (2012 Jan 17)

Post by neufer » Tue Jan 17, 2012 6:10 pm

KCM wrote:
So if the nebula is reflecting blue light, what type of filter would be helpful to observe the Nebula? Or is any necessary?
You want to let light in NOT reduce it.

So why would a filter be necessary (or even desired)?

(Unless, of course, your name is Ann and you don't want to risk the possibility of seeing any red. :wink: )
Art Neuendorffer

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Re: APOD: IC 2118: The Witch Head Nebula (2012 Jan 17)

Post by Ann » Tue Jan 17, 2012 6:33 pm

neufer wrote:
KCM wrote:
So if the nebula is reflecting blue light, what type of filter would be helpful to observe the Nebula? Or is any necessary?
You want to let light in NOT reduce it.

So why would a filter be necessary (or even desired)?

(Unless, of course, your name is Ann and you don't want to risk the possibility of seeing any red. :wink: )
You've got it, Art! :mrgreen:

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Re: APOD: IC 2118: The Witch Head Nebula (2012 Jan 17)

Post by Boomer12k » Tue Jan 17, 2012 9:44 pm

Take cream in your coffee?


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Re: APOD: IC 2118: The Witch Head Nebula (2012 Jan 17)

Post by owlice » Tue Jan 17, 2012 11:35 pm

Boomer12k wrote:Take cream in your coffee?
And jam on your brakes?
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Re: APOD: IC 2118: The Witch Head Nebula (2012 Jan 17)

Post by TNT » Wed Jan 18, 2012 12:01 am

I'll pass on the brakes, owlice-but how about toast? Or even better, a muffin?

I think this is a very interesting image. I need to start looking for these objects myself, if it isn't so cold.
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Re: APOD: IC 2118: The Witch Head Nebula (2012 Jan 17)

Post by wbd » Wed Jan 18, 2012 10:18 am

G'day all.
Pardon my ignorance here but I cannot, for the life of me, identify the "witches head" in this APOD?
Should I be standing on my head to see it, or perhaps on my left ear (yes, I've tried both!) but still can't seem to see anything resembling a witch...
Thanks in advance.

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Re: APOD: IC 2118: The Witch Head Nebula (2012 Jan 17)

Post by Ann » Wed Jan 18, 2012 12:14 pm

The nose of the witch is the bluest protrusion pointing down in the middle of the picture. To the left of the nose is a "wavy line" which is the upper lip, the open mouth and the lower lip of the witch. (The witch has a large yellow "pimple", a bright yellow star, on her upper lip.) At lower left if the witch's chin. Her forehead and hat are presumably at upper right.

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Re: APOD: IC 2118: The Witch Head Nebula (2012 Jan 17)

Post by Indigo_Sunrise » Wed Jan 18, 2012 1:53 pm

wbd wrote:G'day all.
Pardon my ignorance here but I cannot, for the life of me, identify the "witches head" in this APOD?
Should I be standing on my head to see it, or perhaps on my left ear (yes, I've tried both!) but still can't seem to see anything resembling a witch...
Thanks in advance.

Try standing on your RIGHT ear..... :lol: Or just tilt your head to the right and (hopefully) the witch's profile will become apparent.

:mrgreen:
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Re: APOD: IC 2118: The Witch Head Nebula (2012 Jan 17)

Post by wbd » Wed Jan 18, 2012 10:13 pm

Thanks for that explanation - I can now see some semblance of a witch's head... just! :oops: :mrgreen: