Object of the Week, January 26, 2014 – IC 434

IC 434

Diffuse nebula
Orion
RA 05 40 40
DEC -02 27 00

Size 90’ x 14’

IC 434 is a faint emission nebula that runs mostly south from Alnitak, the eastern star of Orion’s belt and is seldom, if ever, observed for its own merits because it silhouettes B33, the iconic Horsehead Nebula. The h-beta filter that is often referred to as “the Horsehead filter”, is actually the IC 434 filter because it boosts the contrast of the emission nebula enough to make the Horsehead much more visible. But let’s put the Horsehead aside for now and appreciate its perennial second fiddle, IC 434.

Attachment 1076

Located about 1500 light years away, it’s part of the huge Orion Molecular Cloud Complex along with all the other well-known nebulae in Orion. But IC 434 is subtle and needs dark skies to be appreciated, even with the h-beta filter. Under the darkest skies it’s surprisingly easy to see without a filter, and can be detected in telescopes as small as 100mm.

The brightest area runs south from Alnitak and to me looks like a rather broad swath of nebulosity with the eastern edge having a distinct boundary, especially around the Horsehead nebula which is why it’s so well defined. Fainter areas extend west, most prominently just west-southwest of Alnitak.

You can’t ignore several other brighter nebulae in this area, the most intricate being NGC 2024, the Flame Nebula. There’s also a string of MAC galaxies running mostly south from Alnilam to just west of the Horsehead Nebula, but that’s another whole observing project.

All this covers a huge chunk of sky. The 90’ x 14” size listed above is from MegaStar, but any measure of IC 434 is simply a reference because deep photos show it extending half way from Alnitak to M42: (http://apod.nasa.gov/apod/ap131029.html).

I began my sketch this past weekend from my usual Oregon observing location under good conditions – 21.25 SQM and good seeing – with my 28 inch Newtonian and a 20 year old Lumicon h-beta filter using magnification from 135x to 235x. The best views I've ever had have been from Steens Mountain in southeastern Oregon at 7400 feet – from there the brighter striations within IC 434 are visible and, dare I say, bring the Horsehead to life.

Attachment 1077 Attachment 1078


"GIVE IT A GO AND LET US KNOW"

I like IC 434, specifically the bright stripe in it that runs parallel to the edge and is bisected by the Horsehead. On one excellent cold night there seemed to be some thread-like texture to the stripe itself (with 16" and H-beta, ~200x). I wish I had dwelt longer on that object then and made a sketch, as well as of the Flame that showed what I thought was mind-boggling detail.

My favorite eyepiece for the Horsehead in my 30" is the 31mm Nagler with the Lumicon H-beta. Seems to give the best views of the "shelf". I need to try one of my Delos on this object.

Duane

Cool region Howard.

Best view of the whole HII region was always with my small 4" f/4 + Hß. Combined with the 17mm Ethos (4mm AP, 4° field, 26x) the N-S lane of IC 434 was always a beauty to look at.

With bigger aperture a tried the region around B33 to see how many detail was visible with 27". I remember a very interesting observation with lots of surprises.
27", 113x-172x, Hß, NELM 6m5+ (Alpine location with very good transparency)
http://www.deepsky-visuell.de/Zeichnungen/B33.jpg

For the next nebula - NGC 2024 I drove to La Palma (28,7°N) and uses the 20" Obsession Dobson with LOMO Sitall optics. The seeing was very bad so that I missed the very fine detail but the transparency was very good.
20", 132x, no filter, NELM 7m+
http://www.deepsky-visuell.de/Zeichnungen/NGC2024.jpg

Excellent sketches Uwe, and your Horsehead looks just like the views I've had with my 28 inch at Steens Mountain - beautiful!

Howard

Amazing sketch Uwe. You must have taken several hours on it.

Last weekend I was at Blue Canyon (5200 ft) and the transparency was very good for that site. Even the winter Milky Way was blazing. I took a 30 second look at the Horsehead with my 22" while taking a break observing Abell GC's and some dim trios. It was obvious without filters, the snout and everything. I just used my 24mm Pan giving 96x.

B33 and IC 434 in Orion: At last! I have made numerous attempts to see the Horsehead, with no success. However, at the 2010 Isle of Wight Star Party, we (myself and Owen Brazell) saw it comparatively easily. IC 434 was easily seen through Owen's 20" Obsession as a fairly faint area of nebulosity taking up half the eyepiece field, and B33 (the Horsehead) stood out against IC 434, as a large (much larger than I expected), dark, semicircular area cutting into the ribbon of IC 434. With averted vision, we could just make out the horse's nose. Much fainter without the filter. 20" f/4.5 120x plus HBeta filter, 13th March 2010

Tonight my wife and I were observing from the Rio Hurtado valley in Chile using my 20” dob. We both saw the Horsehead Nebula with a Lumicon UHC filter. We also saw it with a Lumicon H-Beta filter and it was brighter with that, but the UHC did show it as well. All filters are quite modern ones. I bought them less than 10 years ago.