Deep-sky objects

Re: The Horsehead Nebula

EightHHaggis — Sat, 23 Dec 2006 23:52:27 GMT

Thanks to all who have referred to my Horsehead Nebula web articles.

I appreciate the kind words. It isn't always that way; when I finally worked up the courage to inform readers of sci.astro.amateur of the site, which would take someone about 2 hours or more to read, I noticed that within less than TWENTY minutes of my posting its brand new URL, there was a criticism of it, saying (in effect) that all it would do would be to annoy people, by 'claiming' that it could be seen in small instruments.

Well, it's no "claim". It's a fact. The site has an extensive section on observing and photographing it in small optics, including data of four observers who used a variety of telesecopes in the winter of 1989/90, which I am repeating at the same spot to see if increased light pollution "kills" the Horsehead there. As you'll see from my recent reports added at the end of the article, it is STILL quite visible when (a) the sky darkens enough so that stars of about 5.5 magnitude can be held clearly by DIRECT vision; (b) on nights of superb transparency; and (c) when the HH is nearest the meridian, as high as possible. Furthermore, a filter of the H-Beta type is almost always required, and with one, and a 25 mm Orion Ultrascopic Plossl, I used my wife's little $169 Orion StarBlast 4 inch aperture f/4 reflector to see the HH, repeating some of the feats of the 1989/90 tests. On a superb night, I saw the HH with NO filter, which surpassed any of my previous efforts which had always failed: on that occasion, my 3,400 foot altitude site in the mountains south of San Jose (on private property: sorry!) was "closed in" by ground fog below, cutting off virtually all artificial light, resulting in "high desert rural skies" such as I'd experienced in Nevada.

Within the last two winters I have had views of the HH with my 10 inch f/4.7 (cheap) Orion Dob, and my C-11, that rival the best I've ever had, at this site. I seriously doubt, though, that folks who use low altitudes and who can't get away from light pollution are going to have a lot of luck.

Somebody in this thread said that the HH was about the size of many galaxies that one observes, and gave dimensions. But, unfortunately, they were not quite correct: as far as VISUAL observers are concerned, the HH is only about an arcminute (or 2 at most) wide by perhaps 2 to 3 arcminutes long, as seen in most amateur sized scopes. The published dimension of 6x4 is overstated (re: visual) and based on photographic measurements. It seems incredibly small when viewed with low powers (such as the 16x I employed with my Astroscan, or the 18x in my StarBlast, or in 8x or 11x binoculars.) And, "dark against not quite so dark" is harder to discern than a light galaxy against a dark background, in my experience.

Generally the key to being able to see the HH is the exit pupil employed, not so much the sheer aperture of the instrument. Jack Marling's rules for the appropriate exit pupil for his filters hold well for the HH and the H-beta filter, even if they are made by other companies than Lumicon. You may look at the Lumicon site for a chart, on this page:

http://www.lumicon.com/categories_sub.php?cid=1&cn=Filters

Also, I use those values in doing calculations for filters in my old DOS program, which I now give away free:

http://home.earthlink.net/~steve_waldee/index.html

Furthermore, my program actually can calculate the predicted visibility of the objects in its databases, including the HH, based on various optical parameters and the surface brightness and wavelengths of light to which the eye is sensitive.

When I did my test in '89 and discovered that I *could* actually see a sort of miniscule semblance of the HH using 8x42 binos fitted with H-Beta filters, it was an outlandish claim; but others are now doing it too, though not necessarily with such small aperture. However, the 8x42s had an exit pupil that is within range of the right size for the filter, maximizing the contrast enhancement.

Of course, to see it that way, you're going to have to have a lot of prior visual experience with the object so that you'll know what to expect.

Those of you who are going to attempt to view the HH with a refractor, Mak, or SCT: please try it WITHOUT a star diagonal! This will help enormously unless you are using one of the new premium dialectric ones with 99% reflectance. And, I can say with confidence that often refractors give the best results, their higher contrast -- having no central obstruction -- sometimes making the critical difference. Thus, those of us who did the tests back in '89 found that Rich Page's wonderful AstroPhysics StarFire 7" APO gave us views of the object that rivalled a 17 inch Dob (believe it, or not!)

To find the articles about the HH that I have published, go to the main menu of the HH site:

http://home.earthlink.net/~astro-app/horsehead/index.html

There are three fairly readable articles following a general introduction; the third article "Pt. 3 The 20th Century; Viewing the Horsehead in Small Telescope" has, at the end, a long section on viewing techniques, with many images and links. The other articles deal with its UNKNOWN history: its discovery -- by a female member of the Harvard College Observatory staff -- and all the subsequent photographs published in the next several decades, and my not quite successful attempt to track down PRECISELY who gave it the nickname. The last article is a very long, detailed paper with footnotes (sadly, a few of those references have been lost), which I reconstructed from a copy of the paper that turned up last year. All the original material was sent to Kalmbach Publishing - but they put it in storage and LOST it! I do not have any of the original pictures in the pristine prints that I collected, but did my best to process the xerox copies that I saved, so the FIRST HH photo is indeed included!

Steve Waldee

Re: The Horsehead Nebula

Pavan Keshavamurthy — Fri, 22 Dec 2006 14:02:44 GMT

Oh.. Forgot to mention.

It was without a filter..

Seeing was about moderate.. Light glow in the sky background.

Re: The Horsehead Nebula

Pavan Keshavamurthy — Fri, 22 Dec 2006 13:58:31 GMT

The scope was a 12" F/4.5 Hardin Optical.. Location - Hosahalli Village - 80KM from the city of Bangalore, India..Skies were near 6.5mag (Someone could reportedly see M33 Naked eye.. So that should say it all )..Flame nebula was almost easily there in the field of a 32mm plossl once Alnitak's glare was blocked..

We gave a shot at B33 at higher power... Not that we could actually "see" it.. But we more like "feel", "sense" a dark patch with averted vision..

Re: The Horsehead Nebula

andybyrd — Fri, 22 Dec 2006 01:57:51 GMT

THANKS guys for your help. i did'nt know they made a sky meter. it sounds good i'm gonna try one. i also like the sky charts, i will do both. there will be no second guessing then, thanks for your help,

Andy & Terri Byrd,

Re: The Horsehead Nebula

Bill Weir — Thu, 21 Dec 2006 16:28:44 GMT

Never wrote:
Summer Milky Way or winter Milky Way? There's a big difference and it pretty hard to estimate the limiting magnitude just by that. I see the Milky Way somewhat like that from my backyard but the mag of my skies is hardly even 6.0.
Let's say B33 is in the south. Take a look at M35 without optical aid, can you see it? How about the M36, 37, 38 trio? Just select a good, dark region from the sky and try to see the faintest, pre-selected star you can. I use Perseus like this:
http://www.kolumbus.fi/jaakko.saloranta/Deepsky/Perseus.jpg

Or you can try it like this if it is more to your taste: http://obs.nineplanets.org/lm/rjm.html

Or you can use a SKY Quality Meter http://unihedron.com/projects/darksky/ and not have to deal with whether your eyes are as sensitive as the other guys. The SQM gives a quantitative measurement of the brightness of the sky. This way you will know if the magnitude of the object you are looking for is bright enough to be seen. It's a nice little tool. By the way, M35 is an easy naked eye object from my back yard. Last night my SQM avaerage reading was 20.54 at midnight which equates to around 6.32 NELM. Not a good night. Bill

Re: The Horsehead Nebula

Never — Thu, 21 Dec 2006 09:23:23 GMT

Summer Milky Way or winter Milky Way? There's a big difference and it pretty hard to estimate the limiting magnitude just by that. I see the Milky Way somewhat like that from my backyard but the mag of my skies is hardly even 6.0.

Let's say B33 is in the south. Take a look at M35 without optical aid, can you see it? How about the M36, 37, 38 trio? Just select a good, dark region from the sky and try to see the faintest, pre-selected star you can. I use Perseus like this:
http://www.kolumbus.fi/jaakko.saloranta/Deepsky/Perseus.jpg

Or you can try it like this if it is more to your taste: http://obs.nineplanets.org/lm/rjm.html

Re: The Horsehead Nebula

andybyrd — Thu, 21 Dec 2006 03:40:25 GMT

in general when you can see the milkyway across the sky looking like long thick white cloud about what mag.skys would that be. and how or what stars do you check to see what mag. skys you have. thanks, Andy

Re: The Horsehead Nebula

DaveMitsky — Mon, 11 Dec 2006 15:00:00 GMT

Yes, John, it certainly is. I remember Steve quite well from when he was active on sci.astro.amateur during its heyday.

Just for the record, I saw B33 once again without a filter when I was observing at the summit of Dolly Sods in West Virginia on the night of November 24. This time it was through an 18" Obsession during what was an exceptional night.

Dave Mitsky

Re: The Horsehead Nebula

MaddCow — Sat, 09 Dec 2006 19:40:28 GMT

Never wrote:

Stephen Waldee's HH page can be found here:
http://home.earthlink.net/~astro-app/horsehead/B33_3.htm
If you scroll down a bit you can find that there's a report of Steve spotting B33 with the 8x42 binoculars + H-Beta filters.
/Jake
PS. Steve is a member here so he might add a few notes of his.

Wow, that's an amazing site. Thanks for pointing it out.

Re: The Horsehead Nebula

Never — Fri, 08 Dec 2006 22:25:18 GMT

Stephen Waldee's HH page can be found here:
http://home.earthlink.net/~astro-app/horsehead/B33_3.htm

If you scroll down a bit you can find that there's a report of Steve spotting B33 with the 8x42 binoculars + H-Beta filters.

/Jake

PS. Steve is a member here so he might add a few notes of his.

Re: The Horsehead Nebula

MaddCow — Fri, 08 Dec 2006 20:35:59 GMT

How dark are your skies? If you have good vision, you should find this object FAIRLY easy under dark skies with a nebula filter. I've found I can just barely make out this object under mag 6.5 and darker skies with my 4" refractor with H-beta filtration, but the observation is very marginal. With that small of a scope, IC 434 is steadily visible in adverted vision, but making out the Horsehead is a different matter since the magnification is so low. Still, it's just barely detectable as a little "bump" in IC 434 that comes and goes. There have been reports of people sighting the Horsehead nebula under VERY dark skies with 70mm Binoculars that have an H-beta filter taped to each eyepiece!

Aperture does benefit this object alot, and with my 18" scope and H-beta filtration, I can make out the Horsehead from my backyard that is roughly limiting magnitude 5.5 (Winter Milky Way is just faintly visible). From a dark site, I'd say the object becomes positively easy, and even older guys with much less sensitive vision than me can see it. I've seen the Horsehead nebula without a filter several times, but each time it was at a site that was about mag 6.5 or darker. Last month I observed three times from the Conecuh National Forest, limiting magnitude 6.8+, and even the Horsehead's characteristic shape was visible without a filter.

It all really depends on how dark your sky is, and how sensitive your vision is.

Re: The Horsehead Nebula

tkerr — Thu, 07 Dec 2006 20:35:06 GMT

andybyrd wrote:
WELL I GUESS I SHOULD CLEAN THIS UP, WE DID NOT SEE B33/IT WAS M78 IM VERRY SORRY, for my exited state of mind but i am gonna see b33 / what ever it takes thats my pledge to my wife i think she wants it more than me, THANK YA'LL ALL, VERY MUCH
ANDY & TERRI
OH! I'M STILL GONNA NEED YA'LLS HELP,

No need to be sorry, it isn't a problem. This is what we are all here for. To share our experiences and to learn from each others.

Have A Nice ___________

Re: The Horsehead Nebula

andybyrd — Thu, 07 Dec 2006 03:51:53 GMT

WELL I GUESS I SHOULD CLEAN THIS UP, WE DID NOT SEE B33/IT WAS M78 IM VERRY SORRY, for my exited state of mind but i am gonna see b33 / what ever it takes thats my pledge to my wife i think she wants it more than me, THANK YA'LL ALL, VERY MUCH

ANDY & TERRI

OH! I'M STILL GONNA NEED YA'LLS HELP,

Re: The Horsehead Nebula

andybyrd — Sun, 03 Dec 2006 02:46:03 GMT

HELLO GUYS - now your talking about the one nebula that allows me to spend $$ on astronomy with out ?, because it's my wifes favorite, we were out on the night of the 26th of nov, i/2 way between houston & dallas in a little town called grapeland, very dark skys well any way we were out with our 12'' lx200 for the first time, our old scope was a 10'' lx50- wow what a difference of operation & price, any way again,we only had the cheap 26mm pl,that you get with the scope & believe it or not you could see the horsehead nebula, & we could not see it in the 10'' now you could'nt see head of a horse but you could see the nebula, & we used no filters, weve since ordered the filters & better eyepieces,

thanks for the forum ANDY & TERRI

Re: The Horsehead Nebula

DaveMitsky — Thu, 05 Oct 2006 15:04:29 GMT

I should add that the only time that I ever really found B33 easy to see was when I observed it at the 1995 Winter Star Party in the Florida Keys, where it is 15 degrees higher in the sky than in Pennsylvania, through Tom Clark's 36" Tectron Yard Scope.

Dave Mitsky