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Thread: Object of the Week August 25, 2013 - Abell 64, the “planetary - galaxy”

  1. #1
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    Object of the Week August 25, 2013 - Abell 64, the “planetary - galaxy”

    Abell 64 (= PNG 044.2-09.4; CGCG 397-005, PGC 63630)

    Aquila

    RA: 19 45 35

    Dec: +05 33 52

    Mag: 15,3 NED

    Size: 0,8’x0,5’

    Distance: 39Mpc

    Type: G

    The first reference of our OOTW was given by Zwicky in 1965, when he and his colleagues catalogued thousands of galaxies in the CGCG (Catalogue of Galaxies and of Clusters of Galaxies) catalogue. The raw data did not give any velocity/redshift and so no idea of the distance and the “real type” of the object.

    Second, but the most famous reference of our “PN Glx” was given by Mr. George Abell himself in the year 1966. He numbered the nebula as 64 in his list of 86 new indentified objects from the plates of the Palomar Sky Survey. He classed all objects as “planetary nebula” and concludes a distance of 1700pc for this new object.

    Later, the nebula found entry in the Perek-Kohoutek (PK) Catalogue of Galactic Planetary Nebula, later in the following Strasbourg-ESO Catalogue of Galactic Planetary Nebulae (PNG).

    1996 Marzke, Huchra, Geller presented redshifts for 2020 galaxies selected from the CGCG and listed a redshift of 0.010194 (39Mpc) which indicate this object as a normal galaxy.

    Indeed, the classification of Abell was a misclassification and Abell 64 aka CGCG 397-5 now counts as a galaxy. The typical misclassification is visible perfectly even in smaller telescopes because of a negative reaction of any nebula filter and a missing of a central star.

    The galaxy is visible from the 8”-10” telescope class as a very faint spot of light which disappear when using a filter. From 16” the brightest knot “false central star” is visible and with 24”+ the galaxy showed many spots within the square body. This is the real challenge, to pick up the spots within the galaxy.

    A64_wikisky.jpg
    Wikisky (DSS)

    Abell64.jpg
    27”, 488x, NELM 7m+, Seeing III

    “Give it a go and let us know!”
    Clear Skies, uwe
    http://www.deepsky-visuell.de
    Germany

    27" f/4,2

  2. #2
    Big Jim Jim Chandler's Avatar
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    Hi Uwe,

    Quite by chance and without having researched it, I looked at Abell 64 two weeks ago, on August 13, with the 30". Here are my log notes:

    "Patch of nebulosity seen at all powers. Cataloged as Abell 64 as well as PGC 63630.
    UHC and O-III killed it completely. Without filters, the nebulosity is slightly brighter in the center and attenuates towards the edge. It looks and acts like a galaxy, not a pn."

    I'll have to view it again and look for the knots.

    Jim

  3. #3
    Member hajuem's Avatar
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    Hi Uwe!

    Cool Object!! I will try it this interesting object!! The "false central star" is my challenge!!

    Thank you for the presentation of this object!!

    Lg Hajü
    www.astromerk.de

  4. #4
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    Hi Jim and Hajü,

    these knots were also not on my list but my observing buddy Friedl came with the idea to look after it and it works. An absolutely funny object.

    With your 30" Jim you should give another try to see the knots. I think your observation "slightly brighter in the center and attenuates towards the edge" were the first knots.

    The brightest knot should be visible with 16" Hajü. We tried it with Friedls 16". A few years back when I first look for Abell 64 with 14" and 16" I also noticed the eccentric CS without the knowledge of the knots.
    Clear Skies, uwe
    http://www.deepsky-visuell.de
    Germany

    27" f/4,2

  5. #5
    Member Steve Gottlieb's Avatar
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    Actually, the 1992 Strausberg-ESO Catalogue of Galactic Planetary Nebulae downgraded the status to "Possible Planetary Nebulae" so its not listed in the main catalog and images of "True and Probable Planetary Nebulae".

    I didn't log any knots with my 18", so that's something new to try for with my 24".
    18" (9/25/06): this misclassified "Abell planetary" is a small galaxy situated in a rich star field (galactic latitude -9°). At 220x it appeared very faint, fairly small, slightly elongated, ~35"x30". Not difficult once identified and could be held steadily, though appeared featureless. A small right triangle consisting of two mag 10 stars and a mag 12 star lie close SE (the hypotenuse has a length of ~3') and the galaxy is collinear with the shorter leg.
    Steve
    24" f/3.7 Starstructure
    18" f/4.3 Starmaster
    Adventures in Deep Space
    Contributing Editor, Sky & Tel

  6. #6
    Member reiner's Avatar
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    It's been a few years since I observed this object and I don't remember the observation.

    I did not take any notes except that it was steadily visible at 350x. Definitely worth to have another look at it to try for the internal structure.
    Reiner

    22" and 14" Dobs on EQ platforms and Deep Sky Observing
    www.reinervogel.net

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