Object of the Week September 22, 2013 - Merope's and Barnard's Nebula

[reiner]

NGC 1435 (Merope Nebula) and IC 349 (Barnard's Nebula)

Taurus

RA
03 46 19.57

Dek
+23 56 54.1
coordinates for Merope

Reflection Nebula

Merope Nebula (NGC 1435) is the brightest one of the reflection nebula in the Pleiades. Under good conditions, it is visible even in large binoculars as a faint fan-shaped smudge, extending from Merope outward of the cluster. Merope Nebula is one of those objects that can be hard to observe for the first time and that become relatively easy once you know what to look for.

These reflection nebula are actually not remainders of the molecular cloud in which the open cluster initially formed. Rather, they originate from denser parts of interstellar matter, through which the cluster presently happens to pass through. The visibility of the Merope Nebula is a good criterion to judge the quality of your sky (and btw, it is *very* easy to find ;-) ). I observe it frequently in fall and winter, and I guess most of you do similarly.



Merope's Nebula is therefore not what this is all about and why I chose it as OotW. Superimposed on the large Merope Nebula is a much smaller one, Barnard's Nebula (IC 349), which is brighter, but very close to Merope, extending only 30" from it. IC 349 is considerably more difficult than the Merope Nebula and not just visible at first sight (at least it wasn't at all for me). Instead, it requires a lot of patience to successfully observe it.

When I observed it for the first time, I used a 6mm eyepiece equipped with a strip of black slide film at the field stop. This allows placing Merope behind that strip and to suppress its glare (this is actually the same equipment that I use for Sirius B and some of the fainter moons of Uranus). With a lot of patience, a small appendix to Merope could be made out. Its orientation could be noted using the surrounding small field stars and later be verified using photographs of this object. Barnard's Nebula has a diameter of only 30".



Here is an amateur image by Gert Vandenbulcke (scroll down on the linked page)
http://www.astronomie.be/Tranquility...es/pagem45.htm

Here is an excellent image by the Capella team taken from Crete
http://www.capella-observatory.com/I...bula/IC349.htm

And here is the famous HST image of IC 349
hs-2000-36-a-web.jpg


This is an object that requires excellent seeing conditions, which I rarely have at my usual observing site. So I never went beyond "detection" of the object. I would be very interested in hearing about your observing results of this tiny reflection nebula. Has anybody succeeded to see parts of the structure of Barnard's Nebula?

“Give it a go and let us know!”
Good luck and great viewing!

[Dragan]

Reiner,

What a cool and unique OOTW! I never imagined, or let alone had known, that IC 349 was visible in scopes. I leave next week for a week of observing under some dark skies in western Nebraska. (the site of NSP) This will definitely be on the list.

What a cool challenge object! Thanks!

[Steve Gottlieb]

Barnard's Nebula was discovered visually in November of 1890 using the Lick 36-inch refractor on Mt Hamilton. His discovery note and comments are quite interesting.

"On Nov. 14 [1890] while examining the cluster, I discovered a new and comparatively bright round cometary nebula close south and following Merope, every precaution was taken to prove that it was not a ghost of Merope by examining the other stars of the group under the same conditions. I have since seen it several times and on Dec. 8th I could see it with some difficulty in the 12-inch by occulting Merope with a wire in the eyepiece. With the great telescope the nebula can be seen fairly well with Merope in the field and is conspicuous when the star is placed just outside the north edge of the field. It is about 30" in diameter, of the 13th mag, gradually brighter in the middle, and very cometary in appearance. It was examined with powers of 300, 520 and 1500, with all of which it was comparatively easy."

The following year S.W. Burnham made several observations with the Lick 36-inch and commented --
"I have lately made a set of measures of this singular object from Merope with the 36-inch equatorial. The nebula is readily seen with that instrument when one is aware of its existence, and it can probably be seen now with a somewhat smaller aperture; at the same time, its discovery with any instrument is little less than remarkable, from the difficulty of seeing it at all except when when the bright star is placed outside the field, and, of course, there is only one position which is favorable for this purpose. The distance between the two is so small, that the nebula even then is in the extreme margin of the field, and easily overlooked with careful attention.

[DuaneS]

I agree, a great OOTW! I will try with the 30" next week. This should be a real challenge and a lot of fun to try.

Duane

[Paul Alsing]

Hi Reiner,

Like you, my regular observing site rarely has excellent seeing, so I have only "detected" IC 349 myself, and seeing structure was out of the question! I think it might be easier to see if an occulting bar is used, and I plan on trying this next time out.

There are not many realistic photos of this object because it is usually very overexposed in most pictures, but this one is close...

http://innerberg-astro.lima-city.de/...ebel/IC349.jpg

[Howard B]

This object has given me fits over the years but I know I've seen it well once with my 20" years ago - but I'll be darned if I can find any mention of it in my notebooks. I'm planning a trip to Steens Mountain next week if the weather is good, and IC 349 is near the top of my observing list.

[reiner]

@Steve: Thanks for the mentioning of the discovery story. I think it is amazing to visually discover such an object and a major feat by Barnard. In particular given that it was a very difficult object for me even with the knowledge that it is there.

@ Paul: Yes, there are not that many images that reflect its visual appearance. To me, it was not more than a small appendix to the speckles of Merope.

@Duane and Howard: Let us know about your results. For me, it is as well on the list. I haven't observed it this season and last year I had not been successful. My last successful observation is therefore already some time ago.

[Uwe Glahn]

Cool object Reiner,

my first time is already a few years ago. I call it "Horsehead effect", when you know what to look at, the object is not difficult to see, of course the seeing and the transparency (halo of Merope) has to be fairly good.

With 16" and 600x the RN was visible with Merope outside the field.



A quick look with the 27" shows some structure within the RN. I could not held the structure because of the seeing but it is possible to see more than a nebulous patch.

I always wishes an eyepiece with a baffle in the middle, so you could mask the bright star. Also cool for Abell 12 or Leo I. Unfortunately the new eyepiece design has their field stop inside the front lens. Maybe I have to test is with an simple eyepiece design like a plössl. Does anyone has such a baffled eyepiece in his collection?

[reiner]

Hi Uwe,

your report on Barnard's Nebula several years ago actually started my own interest in this object :-)

I always wishes an eyepiece with a baffle in the middle, so you could mask the bright star. Also cool for Abell 12 or Leo I. Unfortunately the new eyepiece design has their field stop inside the front lens. Maybe I have to test is with an simple eyepiece design like a plössl. Does anyone has such a baffled eyepiece in his collection?

It also works with eyepieces with internal field stops. Of course, you have the open the eyepiece to place the bar to the field stop. In fact, my 6mm eyepiece with the black bar is a Skywatcher 6mm UWA that I did not use anymore and that I optimized to reduce stray light with an internal baffle. Here are two images, it's the middle one in the upper picture, while the lower one shows the additional internal baffle above the negative element (the occulting bar is not shown).

[reiner]

Here a two more pictures showing the occulting bar in my TMB 5mm eyepiece (which replaced the 6mm eyepiece for this purpose)

[Dragan]

Reiner,

What is the bar made of and how is it mounted?

[reiner]

In the old 6mm it was black slide film of the pre-digital age, while in the newer 5mm it is plain black paper. Both work, though the paper has a fuzzier edge. The bar was glued into the field stop using all-purpose glue, such that it is in the focus of the eyepiece.

[Dragan]

Understood.

Thanks Reiner!

In the old 6mm it was black slide film of the pre-digital age, while in the newer 5mm it is plain black paper. Both work, though the paper has a fuzzier edge. The bar was glued into the field stop using all-purpose glue, such that it is in the focus of the eyepiece.

[Howard B]

I was able to see IC 349 On October 4 under a dark sky (21.52) that was full of thin, high clouds. It was faint but not very difficult to see once I had the star just outside the fov, but I found that I had to wait until M45 was near the meridian so IC 349 was between Merope's diffraction spikes. When I tried earlier in the evening, the nebula was right on a diffraction spike and impossible to see. I also found that using the Televue 8-24mm zoom eyepiece worked much better than an Ethos - the edge of the zoom's fov had better contrast! That was perhaps the biggest surprise, but the view was quite nice at 250x to 400x. I haven't scanned my notes and sketches yet yet, but it looked very much like Uwe's sketch.

...Ok, I've added my sketch now:

IC349_crop.jpg IC349_crop_invert.jpg

The nebula was low contrast even with Merope outside the fov, and had a defined, straight edge and an overall triangular appearance but I couldn't see any definite internal detail.

[reiner]

I re-observed Barnards Nebula yesterday (fst 6.0 or even worse, a thin high cloud layer was disturbing). I actually did not expect to be able to be successful. With the 5mm eyepiece equipped with the bar, I placed Merope behind the occulting bar. IC 349 was immediately visible as a faint low contrast protrusion between the two spikes of Merope. The protrusion was shorter than the spikes and broader, very similar as in Howard's sketch. I noted that the nebula's edge distal to the star was quite well defined, yielding the "triangular" appearance noted by others.

I cross-checked by turning the eyepiece and looking at the other "inter-spike" areas, which were, as expected clean. If IC 349 were coinciding with one of the spikes, it's observation would likely have been much more difficult.

I found it quite astonishing that IC349 was visible under these sub-par conditions without much difficulty.

[Astrojensen]

Did you use the 22" or the 14"?


Clear skies!
Thomas, Denmark

[reiner]

With the 22" Dob as for most of my observing time. I use the 14" only occasionally for the moon ;-)