Object of the Week July 15, 2012 - Abell 39

Abell 39

Planetary Nebula in Hercules

Size:155"
Magnitude 12.9
Central Star Mag 15.6

RA 16 27 33.8
DEC 27 54 33

Now how can I possibly post a comparable OOTW after Steve Gottliebs incredible Veil Nebula posting last week! I have some mighty big shoes to fill and I hope you folks find this object worthy!!

Abell 39 is a fairly large but DIM planetary located in Hercules. It is best observed with an OIII filter. What makes Abell 39 noteworthy is its nearly perfect spherical shape that has been observed in scopes as small as 8 inches. In larger scopes the planetary reveals a definitive round shape.

In my 25" with an OIII I've noticed the PN tends to exhibit a brightening along its edge with darkening towards its center. Its round shape is quite obvious appearing nearly perfectly symmetrical. Last year at the Nebraska Star Party, my best views were at 242x.

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As a side route, feel free to shoot for two MAC galaxies that are within Abell 39's circumference. Listed at 17 & 18th magnitude on Megastar, MAC 1627+2754 & MAC 1627+2753 are probably best saved for the absolute best conditions with some very large glass. I personally have never seen these galaxies but then again I've never gone for them under the most ideal of conditions.

Have you?

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And remember,

"GIVE IT A GO AND LET US KNOW"

GOOD LUCK AND GREAT VIEWING!

This is an observation from 4/30/2011 at 216x with NPB filter in my 18" dob on a fair but not great night with Sqm 21.35 and NELM about 6.2 (which for me is well off of a 'great' night). I missed the central star on this observation but saw it 30% on a great GSSP night one year ago.

This is the 4-30-2011 non ideal night:
Abell_39: NPB filter 1/7 fov [3.3'] Averted only and a challenge Round. Not picking up central star. From time to time the central area looks slightly darker. May be brighter rim 7pm [W]. A field star lies just on west edge. Difficult find with star field ID from DSS due to very dim field stars.

I leave off the Adin observation as it is similar except less detailed and only difference was seeing central star 30% from NELM 6.8, 21.7 SQM.

I tried for this one last year with a 10" DK from good skies (SQM 21.7) at about 11,000'. No dice.

Cheers,
Jeff.

Quote:

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Originally Posted by Jeff Young

I tried for this one last year with a 10" DK from good skies (SQM 21.7) at about 11,000'. No dice.
Cheers,
Jeff.

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Hi Jeff, did you have an O III filter on? With 10" it might not be possible without it. We did spot it through a SW Flextube 12" with an O III filter a couple of years ago from 5,000ft on Papoutsa peak (Troodos mountains on Cyprus), but it was extremely hard, only averted vision, and only parts of the periphery were intermitedly visible.

As far as observing Abell 39 with a smaller scope, here are Kent Wallace's observations with an 8-inch:

"At 62.5x, very faint, large disk, requiring the OIII filter and averted vision. The disk is roughly round and diffuse with a faint star involved with the nebulosity. No central star is visible. Fair response to the OIII and UHC filters. No response to the H-beta filter. At 100x can barely see the PN using the OIII and averted vision. At 200x, nothing of the PN is visible. This is definitely a PN to use low power on."

Sounds impressive with an 8-inch?

Well, Uwe Glahn has an observation with a 4-inch here!

I've never attempted this planetary with a small scope but back in 1984 I was able to just hold it steadily with averted vision using an OIII filter in a 13-inch.

Hi Rolandos,

I tried a UHC, but I don't have an OIII at my vacation site in Colorado.

I'll try it from Ireland when I get back home. I've got more aperture there (16") and an OIII, but my home skies are considerably worse.

Jeff.

Like Steve wrote and linked I tried several "easy Abell PN" with my 4" Newton a few years ago. Next to Abell 10, 12, 21, 50 and 81 - Abell 39 could also be seen with that small aperture. I remember this observation very good. The sky was not the very best but to my surprise the PN could be seen for sure as a extremely faint round glow.

With 16" it was always easy to detect. The brighter rim could only seen when transparency was good to very good. The rim was always thicker than on photos.

A never tried the PN with larger aperture than 20", so I missed both background galaxies but I will try it as soon as I could, thanks for the idea.

sketch with 20", 121x, [OIII] home
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Well, I caught this dim fellow today with my 13" under 6.3-6.4 mag skies. It was the second attempt, the first one being unsuccessful mainly due to an inaccurate map.
The only combination that allowed me to see Abell 39 was Pentax XW20 (75x, EP 4.3mm) plus the OIII filter. I could hold it with averted vision 50%-75% of the time. Delos 10mm with the filter turned out to be too dark for this object.
The nebula looked like a very faint round glow, no chance to distinguish brighter/darker parts. I will give it another go with my 18", once I have a chance to do that.

Better late than never! Here is a sketch from my observation of Abell 39 two nights ago under reasonably dark skies at Xyliatos Reservoir, Cyprus. The pn was practically invisible without a filter (I am not sure if I reall saw anything there since I knew it was there!) but it was quite easy with the Lumicon OIII in place, especially at low magnifications. Using the 31mm Nagler on my 18" Obsession (67x), Abell 39 appeared as a round, uniformly lit ghostly disk steadily visible with direct vision. Best view for me though was with the Ethos 13mm (159x). Although at this magnification the planetary became harder to see, it did seem to have a distinct intensity variation, with the southern part kind of fading out. It did remind me of a partial lunar eclipse from a vague, ghostly world!
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