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Thread: Object Of The Week, August 14 2016 - NGC 6914, vdB 131 and vdB 132

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    Object Of The Week, August 14 2016 - NGC 6914, vdB 131 and vdB 132

    NGC 6914, vdB 131 and vdB 132

    HII region with Reflection Nebulae

    Constellation: Cygnus
    RA: 20 25 00.0
    DEC: +42 18 00

    This nebula complex was discovered by Jean Marie Edouard Stephan in 1881. Howard already told us the story of Jean Stephan. Sidney van den Bergh added two of the three reflection parts to his 1966 Catalogue Of Reflection Nebulae.

    According to Harold Corwin on ngcicproject.org, the designation NGC 6914 only applies to one of three reflection nebulae that lie close together. The other two therefore must be vdB 131 and vdB 132.
    Several sources, that can be found via Google, claim, however, that all three reflection nebulae together are called NGC 6914 and vdB 131 applies to the western most one and vdB 132 to the remaining two nebulae.
    SkyTools has a different naming scheme yet again, where the western most part is vdB 131, the center one vdB 132 and the northern most one Bernes 25 and NGC 6914 is vdB 131 and 132 together. A forth part, called Bernes 22, lies slightly south.
    The designations used by SkyTools seem to come from Simbad, though there NGC 6914 is the bright part of the northern most reflection nebula (in accordance with Corwin) and Bernes 25 a detached, small part to the southwest of NGC 6914.
    In short: the naming of these objects is quite messy and I am not sure anymore which part is which. I did find this annotated image of the region online, which seems to favor the Simbad naming.

    N6914-2_id_big.jpg

    According to the information published with APOD of March 4, 2011, the nebula complex lies about 6000 light years from Earth. The dark clouds seen towards the nebulae lie in the foreground. The atoms in the HII region get excited by the ultra violet emission from massive, hot, young stars in the Cygnus OB2 association, while visible light coming from the same stars gets reflected by dust in and near the HII region.

    So, why should this nebula complex be of interest to you? Whenever I am observing reflection nebulae, I always wonder a bit whether the glare I see around stars really is the reflection nebula, or if my optics merely need cleaning.
    Not with these nebulae! My 20" already shows hints of the nebulae at 83x (the lowest magnification I apply using a 31 mm Nagler) without a filter and at 151x (17 mm Ethos) and even 256x (10 mm Ethos) the nebulae are very clearly visible. At 256x I can even see hints of the dark clouds hovering in front of the northern most reflection nebula, especially to the west of the double star embedded in the nebula. The nebula has a sharp edge there and exceedingly faint bits are visible further west. I suppose that is Bernes 25, by the way. Both vdB 131 and vdB 132 stand (relatively) high magnifications as well, though they remain but glares around a triplet and a double star respectively. I didn't try for Bernes 22, nor for the Lynds Darka and Bright Nebulae (LDN and LBN) because I only realised they exist while I was writing this text. I did try to observe the reflection nebulae with my UHC filter and nothing remained visible of them, so that proves their true reflection nature. I didn't notice any nebulosity in other parts of the sky around there, so maybe the LBN objects are too faint or extended to be observed well with a 20" telescope. Maybe a smaller telescope with a wider FOV does show them under very dark skies.

    In other words, lots of challenges in this area of the sky! As always,

    "Give it a go and let us now!"

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    Member Steve Gottlieb's Avatar
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    Very interesting region! Here are my notes using my 18" on several of the objects you highlighted.

    At 73x, this rich Milky Way region contains three sections of reflection nebulosity. The brightest piece (NGC 6914) is located 11' SW of mag 6.9 HD 194708. It involves two mag 11 stars and a mag 12.5 star on the west side. About 6' south is another hazy patch (vdB 132) surrounding a wide mag 9/11 pair at 43". Faint haze connects these two pieces and together they extend ~10'x3' in a N-S orientation. This reflection nebula appears to be bounded on the west side by a non-illuminated dust cloud (Dobashi 2504 = LDN 899?).

    A third weak reflection nebula (VdB 131) is located 12' SSW of the brighter (northern) section of NGC 6914. It involves a group of 10-15 stars (open cluster Dolidze 8) including two mag 9.5 stars and a nice curving arc of stars is just off the southeast side. Overall, the Milky Way is very patchy or dusty in this region so these reflection nebulae do not stand out prominently, though the contrast was improved using a Deep Sky filter.

    To the southeast of the NGC 6914 complex is a very faint, hazy HII region (LBN 279), situated just east of mag 7.5 HD 194669. It appears roughly 10'x6' in size and includes a number of mag 10-11 stars. There was only a weak response to a UHC filter and no response to a (broadband) Deep Sky filter.
    Steve
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    Thanks for your comments, Steve. I haven't tried LBN 279 yet, so you gave me a good reason to revisit the region.

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    I'll give it to try!
    18" f/3.5 New Moon Dob,
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    Member Sue French's Avatar
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    I observed these several years ago, and have pulled their log cards for articles every time I do the area. But I always wondered if anybody would even care. At the moment, they are tentatively pulled for September 2018 column. I wonder if they'll make the cut then.

    Clear skies, Sue

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    Co-Founder DSF.com Jimi Lowrey's Avatar
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    Sue what size scope did you use for your observation?
    Clear Skies,

    Jimi Lowrey
    Fort Davis Texas

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    I guess we will read that in S&T next year

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    Member Steve Gottlieb's Avatar
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    We're talking two years away. Sue, how about posting some of your raw notes here?
    Steve
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    Adventures in Deep Space
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    Member Sue French's Avatar
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    Quote Originally Posted by Steve Gottlieb View Post
    We're talking two years away. Sue, how about posting some of your raw notes here?
    254/1494mm Newt
    22mm Nagler: Dolidze 8 is a 5′ × 2′ collection of 11 fairly bright to faint stars, elongated SE-NW with nebulosity engulfing 3 of the brightest stars, which lie in the NW part of the group. This nebulosity is NGC 6914A. 6′ in PA ~30° from Do 8 is a mag 9/11 star pair cocooned in nebulosity (6914B), and 6′ from 6914B in PA ~350° is a mag 11/12 pair in another little cocoon (6914).
    13mm Nagler: Adds one star to Do 8 and makes 6914 and 6914B a bit more obvious. 6914 engulfs its pair and spreads a little east. 6914B engulfs its pair and extend a little southwest. All 3 still share FOV.

    130/819mm apo
    17mm Nagler: Faint nebulosity. 6914 spreads east and south from its star pair; 6914B spreads west and south from its pair. Both less than 2′. 6014A not apparent. Other nebulosity is in the FOV. Do 8 only shows 6 stars.
    8mm Ethos: 5 more stars in Do 8, ~5.4′.

    These two observations were made a year apart

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