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astrotchr
member
Reged: 07/01/09
Posts: 21
Loc: Ohio
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Colleagues,
I have only recently gained an appreciation for hunting down planetary nebulae, but I have a question about them. Other than M57, M25, and M76, and maybe the Helix, can I expect to see something other than a blue-green spot? Granted, at 210x I can see suggestions of the ansae on the Saturn Nebula, but that is it. Is this typical of what I will be seeing? Are there others that will show structural detail? I am using a 10" f/5 dob.
Thanks,
Paul
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Achernar
Postmaster
Reged: 02/25/06
Posts: 5025
Loc: Mobile, Alabama, USA
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Some will if the seeing is steady. I've seen structure in the likes of the Cat's Eye in Draco, the Blue Snowball in Andromeda and NGC-1535, also known as Cleopatra's Eye in Eridanus. Some will always be nothing but a very tiny, almost stellar disk. Most will be in between, but you'll find steady seeing and high magnifications a must to see detail in most planetary nebulae, and it won't hurt to use a medium to large aperture telescope on them too. A 10-inch can show quite at bit of detail, if not the overall shape of the nebula.
Taras
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15-inch F/4.5 Dob under construction
10-inch F/4.5 Discovery Dob
6-inch F/8 Homebuilt Dob
4 1/4-inch F/4 Homebuilt reflector
A whole bunch of eyepieces, filters and other accessories....
Two curious cats
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David Knisely
Postmaster
Reged: 04/19/04
Posts: 8280
Loc: Beatrice, Nebraska
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Quote:
Colleagues,
I have only recently gained an appreciation for hunting down planetary nebulae, but I have a question about them. Other than M57, M25, and M76, and maybe the Helix, can I expect to see something other than a blue-green spot? Granted, at 210x I can see suggestions of the ansae on the Saturn Nebula, but that is it. Is this typical of what I will be seeing? Are there others that will show structural detail? I am using a 10" f/5 dob.
Thanks,
Paul
There are many which show interesting detail, such as the "mini-dumbell" M76, the Crystal Ball nebula (NGC 1514, with a nebula filter), The Helix (NGC 7293, big, and needs a good OIII filter), and a few others. There are also some rather small ones which show interesting interior detail, but they will often require *very* high power to tease that detail out. With my 10 inch Newtonian, I will frequently use from 350x to as high as 720x on objects like NGC 6543 (Cat's Eye), NGC 2392 (Eskimo), NGC 7662 (Blue Snowball), NGC 7009 (Saturn), NGC 3242 (Ghost of Jupiter), and a number of others. The extreme power helps compensate for the low resolution of the dark-adapted human eye. You have to have excellent seeing to take advantage of that power, but when it does snap, the detail is there. Clear skies to you.
--------------------
David W. Knisely
Hyde Memorial Observatory
http://www.hydeobservatory.info
Prairie Astronomy Club
http://www.prairieastronomyclub.org
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Jeff Young
Post Laureate
Reged: 08/04/05
Posts: 4116
Loc: Ireland
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David and Taras got most of my small favorites, with the exception of the Turtle (NGC6210). I usually observe them in the 450x to 600x range.
But there are also some more larger-sized ones that show good detail. Personal favorites include NGC7008 (Foetus), NGC40 and NGC246 (Skull). No one mentioned M97 (Owl), but I assume you've already checked out that one.
You might be able to see NGC2022 as a small dim ring.
Cheers,
-- Jeff.
--------------------
Nikon 18x70s / UA Millennium Colorado:
Solarscope SF70 / TV Pronto / AP400QMD Coronado SolarMax40 DS / Bogen 055+3130
APM MC1610 / Tak FC-100 / AP1200GTO Tak Mewlon 250 / AP600EGTO
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Dave Mitsky
Postmaster
Reged: 04/08/02
Posts: 10499
Loc: PA, USA, Planet Earth
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NGC 6302 (the Bug Nebula) is a bit different looking. NGC 2438, the planetary nebula associated with M46, is visible as an annulus. NGC 6781 is another possibility.
Dave Mitsky
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Chance favors the prepared mind.
De gustibus non est disputandum.
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David Knisely
Postmaster
Reged: 04/19/04
Posts: 8280
Loc: Beatrice, Nebraska
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I think one of the "wilder" ones is "the Lawn Sprinkler Nebula" (my name for it, not official), NGC 4361 in Corvus. It shows some rather irregular detail that makes it seem to change shape as you look at it. It is sort of diffuse and disk like at low power, but it has patches inside off the brighter core that bear some study at high power or with a nebula filter. The patches remind me a bit of the spiral arcs of water than come off of a rotating lawn sprinkler. Clear skies to you.
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David W. Knisely
Hyde Memorial Observatory
http://www.hydeobservatory.info
Prairie Astronomy Club
http://www.prairieastronomyclub.org
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joec33
super member
Reged: 06/13/09
Posts: 111
Loc: Chester, N.Y
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I had know idea you can use those kinds of mags and still make out detail in planetary nebula with out it getting too dim or fuzzy! I never really went above 200x and I rarley even go that high. Is it really better to view most nebula at higher mags? If so I must be missing out!
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“I'm not perfect, but who are we kidding, neither are you.”
Jeremy Grey
An Over accessorized XT10i
80mm Meade Series 5000 Apo w/duelspeed focuser
Vixen VMC110L
Orion Starblast6
Meade DSI PRO II, Orion S.S Autoguider
Advanced GT Mount
Kendrick Dew System
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astrotchr
member
Reged: 07/01/09
Posts: 21
Loc: Ohio
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Joec33, My thoughts exactly! Now I have to be thinking about a higher power EP--my shortest fl is 5.9 mm. Any suggestions, folks, or should I take that question over to the EP forum?
Also, David, you mention a nebula filter--are you talking OIII, UHC, or some other?
Thanks all,
Paul
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scopethis
professor emeritus
Reged: 05/30/08
Posts: 636
Loc: Kingman, Ks
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I always push the power on planetaries; between 300 and 500x, depending on seeing conditions. Also use both narrowband and OIII filter. Another ring is NGC 6337. Difficult with my 10" SCT but doable.
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sgottlieb
sage
Reged: 07/22/07
Posts: 339
Loc: SF Bay area
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Most planetaries have a high surface brightness and higher power generally reveals more details. Aperture, seeing and optical quality and are all limiting factors, but the general rule is to push it as far as you can go. Here are my last notes on NGC 7027 in Cygnus at various powers, from 12.5x to 807x!
Visible as a mag 8.5-9 "star" at 12.5x in the 80mm finder and easily identified blinking with an OIII filter. At 175x in the 18-inch, appears as a small, very high surface brightness oval with a blue-green color. At 450x, this planetary is elongated 3:2 NW-SE, ~18"x12" and has an unusual bipolar appearance with two lobes. The 10" NW component has a very high surface brightness and contains a quasi-stellar brighter knot on its west edge. A fainter lobe juts out towards the SE and is slightly smaller (~8"). At 565x the SE lobe seems incomplete as if it was partially obscured and the two lobes are encased in a thin outer envelope. The view was fascinating at 807x with the sense of peering at a 3-dimensional object - the brighter NW lobe being closer and the partially overlapping SE lobe extending away in space. At this power both lobes were clearly irregular in shape and surface brightness.
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Steve Gottlieb
18" f/4.3 Starmaster
Adventures In Deep Space
7500+ NGC/IC Visual Descriptions
NGC/IC Project
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David Knisely
Postmaster
Reged: 04/19/04
Posts: 8280
Loc: Beatrice, Nebraska
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Quote:
I had know idea you can use those kinds of mags and still make out detail in planetary nebula with out it getting too dim or fuzzy! I never really went above 200x and I rarley even go that high. Is it really better to view most nebula at higher mags? If so I must be missing out!
No, with most larger diffuse nebulae (and the larger planetaries), it is still best to stay in the low to moderate power ranges (less than 15x per inch of aperture). However, for the smaller high-surface-brightness planetaries, use as much power as the seeing will let you. I recall viewing the Eskimo for many years and only seeing a diffuse disk around the bright central star with maybe a little of the outer ring showing up in its outer haze. However, one night I had the 10 inch up at 720x and was stunned to see the inner part of the "face" looking back at me, surrounded by the "ring" of the Eskimo's parka. I use the OIII filter to help "tone down" the central stars in some of the brighter objects (like the Eskimo or NGC 1514), but in many cases, I have seen about as much detail at these high powers without having to use a filter. Clear skies to you.
--------------------
David W. Knisely
Hyde Memorial Observatory
http://www.hydeobservatory.info
Prairie Astronomy Club
http://www.prairieastronomyclub.org
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David Knisely
Postmaster
Reged: 04/19/04
Posts: 8280
Loc: Beatrice, Nebraska
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Quote:
Joec33, My thoughts exactly! Now I have to be thinking about a higher power EP--my shortest fl is 5.9 mm. Any suggestions, folks, or should I take that question over to the EP forum?
Also, David, you mention a nebula filter--are you talking OIII, UHC, or some other?
Thanks all,
Paul
I try both, as the enhancement level varies a bit depending on the specific object. For most planetaries, the OIII lines are dominant (and an OIII filter the definite choice). However, for some planetaries, the H-Beta line gets nearly as strong, so you do need a filter than can handle both when the need arises (i.e. a narrowband "UHC-like" filter). One example of this is NGC 40, which has an H-Beta line that is nearly twice as strong as the OIII doublet (the H-Beta filter helps this one, but it is best in the narrowband filters). IC 418 (a.k.a. "the Raspberry Nebula) also has strong H-Beta emission, so again, a narrowband filter (Lumicon UHC, Orion Ultrablock, DGM NPB, etc.) would probably be the one to choose. Clear skies to you.
--------------------
David W. Knisely
Hyde Memorial Observatory
http://www.hydeobservatory.info
Prairie Astronomy Club
http://www.prairieastronomyclub.org
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joec33
super member
Reged: 06/13/09
Posts: 111
Loc: Chester, N.Y
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Once again David Kinsely gives awesome advice on filters!! I have bought all my filters off your opinion and have not been let down!! Thank you so much for your incredible advice on the subject!
--------------------
“I'm not perfect, but who are we kidding, neither are you.”
Jeremy Grey
An Over accessorized XT10i
80mm Meade Series 5000 Apo w/duelspeed focuser
Vixen VMC110L
Orion Starblast6
Meade DSI PRO II, Orion S.S Autoguider
Advanced GT Mount
Kendrick Dew System
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scopethis
professor emeritus
Reged: 05/30/08
Posts: 636
Loc: Kingman, Ks
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DAVID--pushing a 10" to 700+ power sounds scary. Most I've had my 10" to is 624x (barlowed an 8mm EP) and was kinda awed that the view wasn't diminished. What EP did you use to achieve this (700+)power?
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David Knisely
Postmaster
Reged: 04/19/04
Posts: 8280
Loc: Beatrice, Nebraska
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Quote:
DAVID--pushing a 10" to 700+ power sounds scary. Most I've had my 10" to is 624x (barlowed an 8mm EP) and was kinda awed that the view wasn't diminished. What EP did you use to achieve this (700+)power?
In my 10 inch f/5.6 Newtonian, I generally use my 5-8mm Speers Waler eyepiece (4.9mm to 7.9mm actual focal lengths) and my 2.5x Tele Vue Powermate (446x to 719x). In my Nexstar 9.25 inch f/10 SCT, I use also use the 5-8mm Speers Waler "bare foot" (297x to 480x), my 10mm Ultrascopic+Powermate (588x), and the Speers-Waler set to 7.9mm with the Powermate (743x). Now that I have the 8.5-12mm Speers Waler, I can use that with the 2.5x Powermate to give me a range of 490x to 691x in my SCT.
For those wondering about how I came up with using ultra-high power on planetaries, I can't take credit for this. I was very dubious of the use of this much power on deep-sky for many years. All that changed when a good friend of mine, Rick Johnson (see the CCD imaging forums for his fine work), totally blew my mind when he showed me the "ghost of Jupiter" NGC 3242 in his 10 inch f/5 Newtonian at around 800x. When I looked in, I saw "the CBS Eye" looking back at me, so that convinced me in a heartbeat. Clear skies to you.
--------------------
David W. Knisely
Hyde Memorial Observatory
http://www.hydeobservatory.info
Prairie Astronomy Club
http://www.prairieastronomyclub.org
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Jeff Young
Post Laureate
Reged: 08/04/05
Posts: 4116
Loc: Ireland
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I normally use the filters (both UHC and OIII) on the larger planetaries when I'm down at 110x to 235x. Above that, most of the time the increased magnification gives me enough contrast and the filters dim the overall brightness too much.
There are exceptions, of course. I found the UHC helpful on NGC7027 even at 500x, and the OIII helpful on the Eskimo at 500x.
On other targets, the filters show different details than the unfiltered, and both views are necessary to build up the "complete picture". An example:
Quote:
M57 Ring Nebula 9/16/2007 21:51 UT; Pickering 6, NELM 6, SQM 20.6
406mm SCT @ 372X, UHC
Unfiltered the outside edge is fairly sharp except to NE, where it fades more unevenly. Inside edge also quite sharp, showing no striations at 260x. Central star in averted perhaps 10% of the time. UHC offers darker background but no other advantage; OIII shows a more ragged outside edge.
510x increases central star to perhaps 25% visibility and offers fantastic image scale. Outer boundary now quite fringed, with inner boundary showing dark striations piercing deep into outer ring. UHC enhances striations somewhat, but at too much light loss -- works better at 375x. Outside edge of southern perimeter slightly brighter than remainder.
Cheers,
-- Jeff.
--------------------
Nikon 18x70s / UA Millennium Colorado:
Solarscope SF70 / TV Pronto / AP400QMD Coronado SolarMax40 DS / Bogen 055+3130
APM MC1610 / Tak FC-100 / AP1200GTO Tak Mewlon 250 / AP600EGTO
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Jeff Young
Post Laureate
Reged: 08/04/05
Posts: 4116
Loc: Ireland
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Quote:
... Another ring is NGC 6337. Difficult with my 10" SCT but doable.
Cool. This one never rises above my horizon in Ireland, but I'll give it a go next time I'm in Colorado. (That will limit me to 10", but with less light pollution and 11,000' less muck to look through than from home.)
Cheers,
-- Jeff.
--------------------
Nikon 18x70s / UA Millennium Colorado:
Solarscope SF70 / TV Pronto / AP400QMD Coronado SolarMax40 DS / Bogen 055+3130
APM MC1610 / Tak FC-100 / AP1200GTO Tak Mewlon 250 / AP600EGTO
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Achernar
Postmaster
Reged: 02/25/06
Posts: 5025
Loc: Mobile, Alabama, USA
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This nebula was surprisingly visible through my 10-inch, even without a nebula filter! It doesn't get all that high above the horizon and there is a lot of light pollution too. The southern end of Scorpius does not get any more than 15 degrees above the horizon here on the Alabama Gulf Coast. Through an O-III filter, the annular shape was very obvious.
Taras
--------------------
15-inch F/4.5 Dob under construction
10-inch F/4.5 Discovery Dob
6-inch F/8 Homebuilt Dob
4 1/4-inch F/4 Homebuilt reflector
A whole bunch of eyepieces, filters and other accessories....
Two curious cats
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stevecoe
"Astronomical Tourist"
Reged: 04/24/04
Posts: 2645
Loc: Arizona, USA
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I agree with the idea of using the filters through moderate powers and then when I get above 250X or so I put the filters away. The "famous and bright" planetaries will take high powers and show plenty of detail during a night of good seeing. The seeing is generally the limiting factor in Arizona where the seeing is often about 2 arcseconds. So, save that high power eyepiece for the best night then go for it.
Enjoy;
Steve Coe
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TeleVue 102 refractor on CGEM mount
10 inch f/4.7 Newtonian
Author "Deep Sky Observing" Springer-Verlag
Author "Nebulae and How to Observe Them" Springer
Canon Xt astrocamera with Hutech modification
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scopethis
professor emeritus
Reged: 05/30/08
Posts: 636
Loc: Kingman, Ks
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Thanks for that data and info on high power David. Makes me wanna start looking for a shorter mm EP to purchase.
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