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Lower's Nebula Sh 2-261 - which filter, which aperture?

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#1 C.Hay

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Posted 23 January 2020 - 06:58 AM

I have a question to the emission nebula afficionados.

 

I'm gearing up for Lower's Nebula, aka Sh 2-261 in Orion.

The first question is: Which filter? I've read that it is largely an H-Beta object, but has some OIII in the centre.

Second question: Which aperture? Reports go as low as 8x42 binoculars. So would starting out with 8x56 bins make sense?

 

I'd be most interested to learn of your observing experience with this little-known, but apparently not-so-hard nebula.

 

CS, Christopher



#2 brentknight

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Posted 23 January 2020 - 12:00 PM

Sue French talks about this one in last months S&T.  It looks very interesting.  I might have a chance to try for this from a site with a gulf front view to the south.  I don't yet have an H-beta, so I'd just have to try the OIII/UHC.



#3 Pcbessa

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Posted 23 January 2020 - 01:58 PM

It is a very faint nebula. Ranks as one of faintest nebulas I have seen.

I have seen in my 10", Bortle4 and Bortle2, with an UHC filter. But it is far fainter than IC434 and the horse head. Don't have a h beta filter.

Its also fainter than the quire faint Jellyfish nebula in Gemini or the less faint Medusa nebula.

Nearby Monkeyhead nebula is by contrast a very bright one.

#4 sgottlieb

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Posted 23 January 2020 - 02:17 PM

I didn't try an H-beta filter -- only an OIII filter -- in a Feb. 2005 observation with my 18".  As you mentioned, the enhanced region was near the center of the 30'x15' nebula.

 

"Lower's nebula was not initially noticed in a rich star field using the 31 Nagler (63x) unfiltered.  Adding an OIII filter, much of the field took on an irregular patchy appearance, partly due to the unresolved background Milky Way glow. But a 10'x8' oval glow (only part of the entire complex) was locally brighter surrounding a group of stars south of the geometric center of the nebula.  The highest surface brightness region (still faint) was an extended patch situated south of mag 8.4 HD 41997 by a few arc minutes."


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#5 j.gardavsky

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Posted 24 January 2020 - 10:24 AM

Hello Christopher,

 

the Lower's Nebula is on my list for a revisit.

 

A report by Steve Coe through his 10" Dob is here https://www.cloudyni...1/#entry4677167 including the comments by Reiner Vogel. The smallest telescope aperture reported has been 5".

 

My last observation is of the 24th February 2014, through my 6" F/5 achro, Astronomik H-Beta filter, and the f=16.3 mm Zeiss 23x/30x B WW eyepiece. Just a faint smudge, no details, but observable.

 

Clear skies,

Jiri

 

PS Edit correct name, sorry Christopher, been in a hurry, not concentrated enough


Edited by j.gardavsky, 25 January 2020 - 05:47 AM.

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#6 Robin

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Posted 24 January 2020 - 11:08 AM

Hi Christopher,

 

I observed it with my 12-inch Dobsonian 3 years ago. Just looked up my observation notes. I saw it with an O-III filter, but especially the Northern part of the nebula was much easier with an H-beta filter.

 

Clear skies

Robin


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#7 C8er

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Posted 24 January 2020 - 09:19 PM

I got this image of it last night from here in New Zealand. ZWO ASI294MC Pro camera through C11 with Hyperstar, on a 10Micron GM1000 HPS mount, with just a UV/IR block filter. Image capture with ZWO AsiAir Pro device. About one hour of 15 seconds exposures.

 

It is a largeish aperture and a very fast f/2 configuration, but it certainly got enough signal in just an hour or so of capture. More would be better of course.

 

https://photos.app.g...7EZ4oghmkjAifS9

 

Cheers,

Chris M


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#8 uwe_glahn

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Posted 25 January 2020 - 09:53 AM

Nice target Christopher,

 

I've logged three observations so far.

 

 

Which filter?

Clearly Hß.

All three main filters does a positive reaction but Hß did the best result, especially for the outer regions.

 

 

Which aperture?

As much as you can fall back.

With my 27-inch the nebula itself is not really a problem. Unfortunately the nebula is too large to detect it as one unit. I could see three separated parts with Hß.

The 4-inch binocular + [OIII] shows only a very faint glow around the central part. (the [OIII] sensitive part)

 

So I think a large binocular, maybe also a 8x56 + Hß or UHC could bring out a nice result.


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#9 C.Hay

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Posted 26 January 2020 - 12:09 PM

Many thanks to all who have responded to my request about how to observe Lower's Nebula.

 

A friend of mine, Holger Münz here in Germany, has supplied by pers. comm. the following observation with 8x42 binoculars:

 

"Instrument: 8x42 binoculars. Filters: H-Beta on the front on one side, UHC on the other, didn't have two H-Beta at the time.

Sky quality: Good rural sky in southern Germany, NELM approx. 6m5.

Dark adaptation: Extremely good, spent 1/2 hour in car listening to music with eyes closed, followed by 1 hour looking through the binoculars with the two filters.

Observation: Noticed towards the end of the observing session, while panning around between Monkey Head Nebula (which appeared very bright!) and Orion, quite by chance a nebula that I identified later at home as Lower's Nebula. Size similar to Monkey Head. Visible with direct vision and easy to find again after panning away and returning.

During the observing session I had previously tested one-eyed and binocular observation of the California Nebula with the filters and found that involving the second eye - even though "only" with UHC - made a major difference to visibility, notably in terms of whether the object was visible directly or only in averted vision."

 

CS, Christopher


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#10 brentknight

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Posted 26 January 2020 - 04:16 PM

Wow. I was just thinking about using different filters in front of each objective. Our eyes are so good at interpolating the view that I thought this might help bring out both the faint H-beta and the OIII. Now I really need to get the H-beta...



#11 Redbetter

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Posted 28 January 2020 - 10:17 AM

Sue French talks about this one in last months S&T. 

Did you mean Sh2-264?  Different and much larger object. 

 

I went after Sh2-261 tonight in dark sky, but with some mixed transparency at the time of the observation (it was a little off.)  I could see some very vague indication in the ST80 at 17x used as an RACI finder.  With the 20" I could see it in more detail, but still not very satisfactorily until I added the H-Beta.  With the H-Beta part of the nebulosity stood out strongly in averted vision and other parts were seen surrounding the triangle of stars more to the WSW.  I couldn't quite trace the nebulosity to/through the stars to the east, although it approached them.  It was framed well in the 31T5 in the 20".


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#12 sgottlieb

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Posted 30 January 2020 - 02:04 AM

By the way, the Lowers (father and son amateurs from San Diego) discovered the nebula in 1939 on photographs taken with their homebuilt f/1 Schmidt camera.  A rare mid-20th century amateur deep-sky discovery and perhaps more surprising as the Schmidt camera had only been invented 9 years earlier.


Edited by sgottlieb, 30 January 2020 - 10:10 PM.

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#13 C.Hay

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Posted 01 February 2020 - 07:33 AM

Thanks to all for their insightful replies. Holger has probably pushed the envelope with his 8x42 sighting. I have yet to find an opportunity to pursue it with 8x56 binoculars plus all kinds of filters, but will certainly do so and will report here.

 

Uwe discusses the differences between H-Beta and OIII. 

 

Regarding the latter, there is currently a very interesting thread on Lower's Nebula in the astrophotography board:

https://www.cloudyni...er#entry9942971

Post #10 in that thread presents an OIII capture, i.e. a photo showing the OIII region alone. Apparently there is a dove's head in the nebula!

 

CS, Christopher


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