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Thread: Object of the Week October 5, 2014 - NGC 908 & the NGC 908 Group - Cetus

  1. #1
    Member Paul Alsing's Avatar
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    Object of the Week October 5, 2014 - NGC 908 & the NGC 908 Group - Cetus

    Object of the Week October 5, 2014 NGC 908 & the NGC 908 Group - Cetus
    NGC 908, Herschel 37, MCG -4-6-35, ESO 545 11, PGC 9057 in Cetus
    intermediate orientation spiral galaxy (SABc)
    RA: 02h23m04.6s
    Dec: -21°14'02" (2000)
    Size: 6.2'x 2.8'
    Mag: 10.2V
    Mag: 10.8B

    NGC 908 is a spiral galaxy, discovered in 1786 by William Herschel (and is #37 on the Herschel 400 list), and is a so-called starburst galaxy, that is, a galaxy undergoing a phase where it spawns stars at a frantic rate. Clusters of young and massive stars can be seen in the spiral arms. This galaxy, about 65 million light-years distant, almost certainly has had some kind of interaction with another galaxy in the past to cause this activity, although there is no sign of an interloper in the area.

    The most interesting feature of this galaxy, by far, is the easternmost of the 2 prominent spiral arms, which about halfway along its length clearly splits into 2 distinct tails.

    ngc 908 inv.jpgngc 908.jpg

    My own best observation of this guy was in November of 2006, using the 82" @ McDonald Observatory near Fort Davis, Texas, on a perfect sub-arcsecond night. The galaxy completely filled the 5 arc-minute field of view and the bright H-II star-forming areas seemed to cover the entire galaxy. The split tails of the easternmost arm looked like braided rope, the detail was incredible. This object was one of the nicest surprises and best highlights of the entire weekend. Subsequent observations using my own 25" dob were not quite as spectacular, as you might guess, but this is still a fun galaxy to observe, especially on a night with great seeing.

    NGC 908 is the anchor galaxy for the NGC 908 Group, which has 8 members, including NGC 908, NGC 907, NGC 899, IC 223, PGC 8666, ESO 544-30, ESO 545-2, and ESO 545-16. Only the NGC & IC galaxies are within 30 arc-seconds of NGC 908, the others are up to 2 degrees away. I have seen the closer galaxies, but they do not really present themselves as a really cool galaxy cluster because I needed to move the telescope a bit and can't fit them all into the same FOV.

    The only reason I bring up this group of galaxies at all is because of what I learned while researching them. I had no idea that there are as many different catalogues of galaxies groups or clusters as there are, and this group has many designations that are new to me... as follows;

    The NGC 908 Group is also known as...

    NBGG 52-06 (Nearby Group of Galaxies)
    MCL 83 (Maia+da Costa+Latham) = (Grm) = (MDCG) = (MdCL) = (MDL) !!!
    LGG 56 (Lyon Group of Galaxies) AKA the Garcia Galaxy Groups
    NOGG H 158 (Nearby Optical Galaxies Group)

    Wow! Well, I try to learn something new every day, and clearly today is no exception.

    Give it a go and let us know!
    Paul Alsing
    25" f/5 Obsession
    http://www.pnalsing.com/home

  2. #2
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    Unfortunately a little bit to low in the sky here in Germany I catches this galaxy from Morocco (30,2°N).

    With the for me unusual 16" Schmidt-Cassegrain telescope type (note the mirrored image) the splitting of the arms very visible as an easy detail. Transparency was very good, Seeing was poor.

    16" SCT, 239x, fst 7m+, Seeing III-IV (Sahara Sky/Morocco)
    Clear Skies, uwe
    http://www.deepsky-visuell.de
    Germany

    27" f/4,2

  3. #3
    Member Steve Gottlieb's Avatar
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    Although NGC 908 is the real showpiece in this group, I wanted to mention that NGC 899 to the northwest is also irregular and the brightest member in a subgroup -- KTS 16! (catalog of isolated triplets of galaxies in the southern hemisphere)

    24" (10/3/13): NGC 899 is the brightest (or highest surface brightness) in a trio (KTS 16) with IC 223 5' NNE and NGC 907 17' NE. At 375x appeared fairly bright, moderately large, irregular, ~0.9'x0.7'. A very faint extension was repeatedly visible on the southeast end protruding towards the east. This asymmetry is confirmed on the DSS, which reveals a chaotic system with knots. A wide pair of mag 13 stars is less than 2' SW.
    Last edited by Steve Gottlieb; October 7th, 2014 at 08:42 PM.
    Steve
    24" f/3.7 Starstructure
    18" f/4.3 Starmaster
    Adventures in Deep Space
    Contributing Editor, Sky & Tel

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