Jump to content


Photo

IC 434 & B 33: The Horsehead Nebula

  • Please log in to reply
20 replies to this topic

#1 cildarith

cildarith

    Mercury-Atlas

  • *****
  • Moderators
  • Posts: 2668
  • Joined: 26 Aug 2004
  • Loc: San Diego, CA

Posted 22 February 2010 - 08:50 PM

Object Name: IC 434
Also Known As: Barnard 33, LDN 1630, Horsehead Nebula
Object Type: Emission Nebula + Dark Nebula
Constellation: Orion
Right Ascension (2000.0): 05h 40m 59.0s
Declination (2000.0): –02° 27' 30"
Magnitude:
Dimensions: 60' x 10'; 6' x 4'
Distance: 1,500 light years
Discovery: William Herschel, 1 February 1786 (18.7" Reflector)
NGC Description: neb, 60' l, south from Zeta Ori

Telescope: Parks Astrolight EQ6 • 6" f/6 Newtonian Reflector
Eyepiece/Magnification: 15mm Parks Gold Series Plössl • 60x • 52' FoV
Date/Time: 14 February 2010 • 04:00-05:00 UT
Observing Location: Oaksanita Springs, Descanso, San Diego Co., California, USA
Transparency: NELM 6.3, TLM 14.2
Seeing: Pickering 8
Conditions: Clear, calm

One of the most elusive grails of visual astronomy is the fabled Horsehead Nebula, a protrusion of dark nebulosity superimposed on a gossamer veil of exceedingly faint nebulosity dangling from the easternmost star in Orion's belt known as IC 434. It has been quite a few years since I last observed this object and it proved to be as difficult as ever.

The only thing easy about the Horsehead Nebula is finding the correct location. Center your scope on second-magnitude Alnitak (Zeta Orionis) and sweep a mere ½° south; the object of your search (believe it or not) is now in your field of view, and if you are at a dark sky site on a moonless night, you might catch a glimpse of this emission and dark nebula combination.

Make sure that the blinding glare of Alnitak is removed from the field of view (I achieved this by selecting the 15mm Plössl, which provided a good compromise between low magnification and a small enough field of view to exclude the bright star). If the Horsehead is still not readily visible, carefully examine the background sky visible through your eyepiece and see if you can discern that the western half of the field is subtly brighter than the eastern. Gently move your scope from east to west and back again to pick up the relatively sharp western edge of the IC 433 HII region. Once you have identified this edge between the dark and not-quite-so-dark halves of the field of view, look for a small notch or gap one third of the way from HD 37805 to HD 37806, a pair of 8th magnitude stars separated by 24' and aligned north-south.

The emission portion of the nebula (IC 433) is likely ionized by the blue giant star Sigma Orionis and is estimated to lie at a distance of 1,500 light years. William Herschel discovered this object on February 1st, 1786. The dark nebulosity, which makes this region so famous, was catalogued by E. E. Barnard as the 33rd object in his famous catalogue of dark nebulae, published in 1927. Its first treatment in the professional literature can be traced to Barnard's 1913 Astrophysical Journal article "Dark regions in the sky suggesting an obscuration of light." Barnard's three paragraph description of the as yet unnamed and uncatalogued object is worth reading. You may review the actual article here (see pages 500-501, beginning at the midpoint of page 500).

An additional object of interest may be found in the same field of view. This is the reflection nebula NGC 2023 surrounding the star HD 37903. This nebula is surprisingly prominent (way easier than the Horsehead) and, in my opinion, one of the best examples of a reflection nebula for the visual observer. It exhibits a satisfying amount of structural detail and takes magnification well. Be sure to check out this overlooked object next time you're in the area.

Attached Files



#2 mathteacher

mathteacher

    Mercury-Atlas

  • *****
  • Posts: 2782
  • Joined: 13 May 2007
  • Loc: Oakland, CA

Posted 22 February 2010 - 09:15 PM

Eric, congratulations on a wonderful sketch and informative and entertaining post. Consider me a fan of your work!

#3 GlennLeDrew

GlennLeDrew

    Voyager 1

  • *****
  • Posts: 10580
  • Joined: 17 Jun 2008
  • Loc: Ottawa, Ontario, Canada

Posted 22 February 2010 - 10:03 PM

Most excellent! Very evocative of the view I've had in a 16" newt.

By the way, my impression is that IC434 is the illuminated edge of one of the giant molecular clouds in the Orion OB1 complex. The illumination source is rather more likely to be sigma Ori, rather than Alnitak. One suggestive piece of evidence is the streaming of gas, like wispy cirrus, perpendicular to the ionization front and pointing toward sigma.

The younger parts of Ori OB1 are in the distance interval 1,300-1,500 l-y. In addition to IC434 and numerous reflection nebulae around Orion's Belt, this includes Orion's Sword and the Belt stars (part of Cr 70).

#4 cildarith

cildarith

    Mercury-Atlas

  • *****
  • Moderators
  • Posts: 2668
  • Joined: 26 Aug 2004
  • Loc: San Diego, CA

Posted 22 February 2010 - 10:43 PM

Thanks for the kind words, mathteacher!

Glenn - you are correct. Thanks for the info. :)

#5 JayinUT

JayinUT

    I'm not Sleepy

  • *****
  • Posts: 3933
  • Joined: 19 Sep 2008
  • Loc: Utah

Posted 22 February 2010 - 11:54 PM

Eric,

A really well done guide and report and an outstanding sketch. I'm glad you posted this.

#6 frank5817

frank5817

    Cosmos

  • *****
  • Posts: 8390
  • Joined: 13 Jun 2006
  • Loc: Illinois

Posted 23 February 2010 - 12:35 AM

Eric,

Stunning sketch of this deep sky pair. One feature that is so impressive about the sketch is that you were able to represent the horsehead with the proper contrast. Excellent write up and good searching to include Barnard's first description. Very classey post. :waytogo:

Frank :)

#7 cildarith

cildarith

    Mercury-Atlas

  • *****
  • Moderators
  • Posts: 2668
  • Joined: 26 Aug 2004
  • Loc: San Diego, CA

Posted 23 February 2010 - 12:56 AM

Jay: My pleasure; I'm glad you enjoyed the report. :)

Frank: Thanks - in reading the rest of the article, it is amazing to me that less than one hundred years ago, visual descriptions of objects as seen through the eyepiece were actually published in the Astrophysical Journal.

#8 CarlosEH

CarlosEH

    Fly Me to the Moon

  • *****
  • Posts: 7179
  • Joined: 19 Jan 2005
  • Loc: Pembroke Pines, Broward County, Florida

Posted 23 February 2010 - 01:17 AM

Eric,

An outstanding observation and report of the famous Horsehead Nebula (IC 433/B33) in Orion. This is the finest observation of the Horsehead Nebula that I have ever seen with this size aperture instrument (even with larger apertures as well!). You have captured this infamous emission/dark nebula perfectly in your fine rendering. Thank you for sharing it with us all.

Carlos

#9 S1mas

S1mas

    Mariner 2

  • -----
  • Posts: 266
  • Joined: 08 Dec 2009
  • Loc: Lithuania

Posted 23 February 2010 - 01:35 AM

Just WOW Eric :)

#10 cildarith

cildarith

    Mercury-Atlas

  • *****
  • Moderators
  • Posts: 2668
  • Joined: 26 Aug 2004
  • Loc: San Diego, CA

Posted 23 February 2010 - 08:46 AM

Thanks Carlos and S1mas!

#11 ladip63

ladip63

    Viking 1

  • -----
  • Posts: 813
  • Joined: 17 Oct 2007
  • Loc: the dark skies of Texas

Posted 23 February 2010 - 01:14 PM

WOW!!!! Eric That is spectacular. :bow:
Lynn

#12 cildarith

cildarith

    Mercury-Atlas

  • *****
  • Moderators
  • Posts: 2668
  • Joined: 26 Aug 2004
  • Loc: San Diego, CA

Posted 23 February 2010 - 02:22 PM

Thank you Lynn!

#13 Jef De Wit

Jef De Wit

    Mercury-Atlas

  • *****
  • Posts: 2734
  • Joined: 06 Mar 2009
  • Loc: Hove, Belgium

Posted 23 February 2010 - 03:09 PM

:bow: :bow: :bow: Just impressive! I hope I will see the Horsehead once before I die...

#14 phxbird

phxbird

    Mariner 2

  • -----
  • Posts: 252
  • Joined: 24 Dec 2007
  • Loc: New Mexico, USA

Posted 23 February 2010 - 09:16 PM

I will have to try again with my 8" Dob before Orion gets to low. We have a dark sky site 30 miles north of town so I will have to try it soon. Great sketch and article!

#15 cildarith

cildarith

    Mercury-Atlas

  • *****
  • Moderators
  • Posts: 2668
  • Joined: 26 Aug 2004
  • Loc: San Diego, CA

Posted 24 February 2010 - 11:07 AM

Paul and Jef: Thank you! Best of luck with your own attempts at finding the elusive horsehead.

#16 rolandlinda3

rolandlinda3

    Gemini

  • *****
  • Posts: 3401
  • Joined: 24 Jan 2006
  • Loc: Crozet VA 22932

Posted 24 February 2010 - 11:30 AM

That is a fine piece of observing and sketching.

#17 niteskystargazer

niteskystargazer

    Gemini

  • *****
  • Posts: 3061
  • Joined: 05 Oct 2009
  • Loc: 41-43'-28" N 87-42'-39" W

Posted 24 February 2010 - 01:43 PM

Eric,

:waytogo:, nice sketch.

:thanx:,

Tom

#18 mandotrout

mandotrout

    Ranger 4

  • *****
  • Posts: 372
  • Joined: 25 Jan 2009
  • Loc: Montana, USA

Posted 24 February 2010 - 02:45 PM

Great sketch, and great observation; especially without the H(orsehead)-beta filter. :) I have yet to really see it without the filter.

#19 cildarith

cildarith

    Mercury-Atlas

  • *****
  • Moderators
  • Posts: 2668
  • Joined: 26 Aug 2004
  • Loc: San Diego, CA

Posted 24 February 2010 - 07:28 PM

Thanks for your comments, Roland, Tom and Jeff! :)

#20 Achernar

Achernar

    Cosmos

  • *****
  • Posts: 9030
  • Joined: 25 Feb 2006
  • Loc: Mobile, Alabama, USA

Posted 25 February 2010 - 02:39 PM

It is a real accomplishment to see the Horsehead with a 6-inch, and your drawing is excellent. It's a testament to the dark and clear skies you have, in my area there is no way you would see this object with a 6-inch. I observe it with my 10-inch, and even then it's not an easy object to see.

Taras

#21 cildarith

cildarith

    Mercury-Atlas

  • *****
  • Moderators
  • Posts: 2668
  • Joined: 26 Aug 2004
  • Loc: San Diego, CA

Posted 26 February 2010 - 12:04 AM

Thank you Taras. It is certainly a challenging target for the 6-inch and the dark skies are the most important part of the equation.






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics