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Observing >> Deep Sky Observing

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nytecam
Postmaster

Reged: 08/20/05

Loc: London UK

Campbell's Star anyone?
#5369545 - 08/15/12 05:31 AM Attachment (32 downloads)

Campbell's Star is a brightish mag 9.6 near stellar PN in Cygnus immediately north of Albireo. Sometimes described as a proto-planetary nebula and variously named HE2-438, PK64+5.1 and PNG 64.7+5.0. The PN is in a crowded Milky Way starfield but if a static scope is centred on globular M56 to the west, Campbell's Star will transit the field 18 minutes later ~20' [2/3 moon diam] to the north of centre. A high magnification needed to see it's nonstellar.

When imaged a long focal length needed [I used my Meade 3000mm f/10 SCT+SX Lodestar-C OSC cam] as the PN disk is only 7.5"arc diam eg twice the diam of planet Uranus! It records, as its name implies, as bright red or pink - a feature shared in my pics of PNe "Bowtie" NGC 40 in Cepheus and IC418 in Lepus as posted on YouTube and via my link below.

Well worth a look as perfectly placed after dusk currently and throughout the autumn. As cloud intervened last night I was going to dump my sole 10s test exposure [below] but glad I didn't! Field stars to mag 13 are recorded and the PN is clearly non-stellar and very pink! I need to return for more

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nytecam
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Reged: 08/20/05

Loc: London UK

Re: Campbell's Star anyone? new

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[Re: nytecam]
#5371122 - 08/16/12 06:24 AM Attachment (17 downloads)

Campbell's Star probably too small for visually maybe.

But dug out an old pic showing why it's pink via a simple spectrum taken with my homemade spectroscope [Barlow+DV-prism+afocal cam] eg the very strong hydrogen-alpha emission @ 656nm in red - the other emission lines are very weak by comparison.

For direct comparison is a shot of M57 through the Rainbow Optics grating - clearly the green-blue merge of OIII+H-beta dominate with H-alpha weak. Hope it's of interest

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David Knisely
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Reged: 04/19/04

Loc: southeastern Nebraska

Re: Campbell's Star anyone? new

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[Re: nytecam]
#5371639 - 08/16/12 01:56 PM

Quote:

Campbell's Star probably too small for visually maybe.

Nope, its main disk is around seven or eight arc seconds across, so under good seeing conditions, it can be seen as something other than star-like. Megastar lists it as being 35" arc in diameter, but I have never seen an outer shell to it, and it seems quite small on deep images of the object. Its dim somewhat reddish color is a dead giveaway in my 9.25 inch SCT, making it fairly easy to pick out in the star field, although the disk itself isn't all that well defined. Clear skies to you.

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JimK
professor emeritus

Reged: 09/18/05

Loc: Albuquerque, NM USA

Re: Campbell's Star anyone? new

new

[Re: David Knisely]
#5371685 - 08/16/12 02:28 PM

Quote:

Quote:

Campbell's Star probably too small for visually maybe.

Nope, its main disk is around seven or eight arc seconds across, so under good seeing conditions, it can be seen as something other than star-like.

Agreed. I saw it on 18-19 Jun'12 with my C-8 at about 180x. I noted it as a fuzzy star with a very, very light pink color, not responsive to my O-III filter.

It is included on the Astronomical League requirements for the Planetary Nebula award as BD +30 3639 (pg 48 in the observing guide).

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Carol L

Reged: 07/05/04

Loc: Tomahawk, WI 45N//89W

Re: Campbell's Star anyone? new

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[Re: nytecam]
#5371850 - 08/16/12 04:36 PM

Thanks for the heads-up on this one - love the color!

I seem to recall reading some advice to use an H-beta filter, and then look for a small red ring of emission surrounding the star. I'll definitely give it a look ASAP and also check out Minkowski's Footprint while i'm in the neighborhood.

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Matt2003
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Reged: 04/22/10

Re: Campbell's Star anyone? new

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[Re: Carol L]
#5372095 - 08/16/12 07:42 PM

If its about the size of Uranus's disk, it should be Non-stellar at high magnification in my scope. Probably with much difficulty, but no impossible..

Clear Skies,
Matt

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Bill Weir
Carpal Tunnel

Reged: 06/01/04

Loc: Metchosin (Victoria), Canada

Re: Campbell's Star anyone? new

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[Re: Matt2003]
#5372451 - 08/17/12 01:03 AM

There actually was a report on viewing this recently. It's in the new 24" Spica Eye report in the reflectors section.\
http://www.cloudynights.com/ubbthreads/showflat.php/Cat/0/Number/5344116/page/2/view/collapsed/sb/5/o/all/fpart/1

It stimulated me to have a go after the ring portion recently with my 20". My sighting of it was marginal as a diffuse haze around the star that was somewhat annular. There was no colour to this ring. The star was more of an orangey colour. I suspect a darker location would be needed, as my backyard SQM reading that night was only 21.14. The seeing was horrible also so I couldn't push the power past 365X. Perhaps tonight I'll give it a go as the seeing has been excellent the last couple of nights. Last night I was able to push the power to 800X. Hand tracking was difficult to say the least. ; )

Bill

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David Knisely
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Reged: 04/19/04

Loc: southeastern Nebraska

Re: Campbell's Star anyone? new

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[Re: Carol L]
#5372491 - 08/17/12 01:53 AM

Quote:

Thanks for the heads-up on this one - love the color!

I seem to recall reading some advice to use an H-beta filter, and then look for a small red ring of emission surrounding the star. I'll definitely give it a look ASAP and also check out Minkowski's Footprint while i'm in the neighborhood.

It depends on the H-Beta filter used. My Lumicon H-Beta has a whopping "red leak" secondary passband, so this "planetary" looks quite reddish with that filter. However, some other H-Beta filters don't have the red secondary passband, so the object would either appear pale bluish or without color at all. Clear skies to you.

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nytecam
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Reged: 08/20/05

Loc: London UK

Re: Campbell's Star anyone? new

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[Re: Carol L]
#5372568 - 08/17/12 04:41 AM Attachment (10 downloads)

Quote:

Thanks for the heads-up on this one - love the color! I seem to recall reading some advice to use an H-beta filter, and then look for a small red ring of emission surrounding the star. I'll definitely give it a look ASAP and also check out Minkowski's Footprint while i'm in the neighborhood.

Carol - if you check my spectrum [above] you'll see the H-alpha line in red completely dominates [<100%] whilst OIII + H-beta to left is ~5% but I think H-alpha is so bright it should punch through visually - good luck

My better pic from Wednesday night below under clear conditions and exposure again the minimum [10s] to avoid burning out this PN - central star m12.5 [Megastar] and field stars to mag 16 recorded [Sloan DSS]. Measuring the disk [main image] in my pic = 8.2"-arc eg close to published figure

Inset top left enlarged x2; lower left log scaled to show possible outer halo

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Carol L

Reged: 07/05/04

Loc: Tomahawk, WI 45N//89W

Re: Campbell's Star anyone? new

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[Re: nytecam]
#5373146 - 08/17/12 12:55 PM

Thanks David, it sounds like the filter advice was written by a Lumicon user - that's the one i have.

Maurice, thanks for the spectrum explanation and the new pic. I've always preferred unfiltered views, so if the sky cooperates tonight i'll take a look without the filter, and then with it.

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nytecam
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Reged: 08/20/05

Loc: London UK

Re: Campbell's Star anyone? new

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[Re: Carol L]
#5374195 - 08/18/12 04:35 AM Attachment (11 downloads)

Thanks Carol - what a buzz last night. Got a shot via Rainbow Optics grating for a beautiful colour spectrum of this star and includes M57 for comparison - note red image at 656nm and cyan OIII+H-beta blend ~500nm - these corrolate with Campbell's Star spectrum above and, due to tiny PN's size, are sharper and better resolved in OIII and H-beta lines in green/blue boundary just evident.

The yellow line is probably helium. The faint emission lines [brighter blobs] extend to the extreme blue to right fading ~400nm are probably hydrogen lines. As the camera is unfiltered [apart from Rainbow grating!] the spectrum extends into the invisible infra-red region eg the colourless part of spectrum to extreme left to ~800nm ! More work to extract and 2D profile showing line intensity - good fun

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Carol L

Reged: 07/05/04

Loc: Tomahawk, WI 45N//89W

Re: Campbell's Star anyone? new

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[Re: nytecam]
#5374636 - 08/18/12 12:42 PM

My clouds cooperated last night too, so i rolled the 16" Lightbridge 'Seymour' (see-more

) out of the shed, and found Campbell's Hydrogen Star via M56 - quite an easy starhop.

Low power (57x _ 32mm Plossl) showed a ruddy-tinted star, much like a weakly colored variable. The seeing wasn't good enough to support the 7mm Axiom (261x) or the 5mm Nagler (366x), but the 9mm SWAN (203x) was perfect.

When i stared directly at the 12.5 central star, i could plainly see a thin ruddy shell surrounding it. Awesome!!

I was more than satisfied with the unfiltered view, so the Lumicon never made it out of the eyepiece case. What a fun target.

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nytecam
Postmaster

Reged: 08/20/05

Loc: London UK

Re: Campbell's Star anyone? new

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[Re: nytecam]
#5377647 - 08/20/12 02:05 PM Attachment (9 downloads)

Quote:

Quote:

Thanks for the heads-up on this one - love the color! I seem to recall reading some advice to use an H-beta filter, and then look for a small red ring of emission surrounding the star. I'll definitely give it a look ASAP and also check out Minkowski's Footprint while i'm in the neighborhood.

Carol - if you check my spectrum [above] you'll see the H-alpha line in red completely dominates [<100%] whilst OIII + H-beta to left is ~5% but I think H-alpha is so bright it should punch through visually - good luck

My better pic from Wednesday night below under clear conditions and exposure again the minimum [10s] to avoid burning out this PN - central star m12.5 [Megastar] and field stars to mag 16 recorded [Sloan DSS]. Measuring the disk [main image] in my pic = 8.2"-arc eg close to published figure Inset top left enlarged x2; lower left log scaled to show possible outer halo

My recent spectrogram of Campbell's Star measures OIII=19%; H-beta=7%; He=13% with H-alpha=100% so a OIII filter would be more efficient visually than H-beta which is only ~1/3 as bright as OIII

Still think the bright H-alpha should punch through visually as you found Carol

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Carol L

Reged: 07/05/04

Loc: Tomahawk, WI 45N//89W

Re: Campbell's Star anyone? new

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[Re: nytecam]
#5377893 - 08/20/12 04:10 PM

Quote:

Still think the bright H-alpha should punch through visually as you found Carol

It certainly did!

The ruddy color surrounding the star was quite narrow, and was only seen when looking directly at the star - averted vision bloated the nebulosity and made it turn white.

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