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Thread: Object of the Week November 30, 2014 - Arp 133 and Minkowski’s Object

  1. #1
    Member Howard B's Avatar
    Join Date
    Feb 2012
    Portland, Oregon USA

    Object of the Week November 30, 2014 - Arp 133 and Minkowski’s Object

    Irregular Starburst Galaxy
    RA 01h 25m 47s
    DEC -01° 22′ 21”

    Magnitude: 16.15
    Size: 0.3’ x 0.4’

    (SDSS image)

    Part of Arp 133 group, which has NGC 541 as its dominant and brightest member, Minkowski’s Object (MO) is of particular interest because it’s a small, irregular starburst galaxy that was apparently formed by NGC 541’s radio jet out of a nearby patch of the intergalactic medium that was slightly warmer and denser than average. For a more complete discussion, check out this link:

    Observationally, Minkowski’s Object is a challenge. I’ve found it more difficult that the magnitude 16.15 value I found online (NED) and in book The Arp Atlas of Peculiar Galaxies – A Chronicle and Observer’s Guide by Jeff Kanipe and Dennis Webb (Willmann-Bell).

    The SDSS DR9 navigate tool indicates the magnitude of MO is approximately 20.5, but that’s much fainter than experience shows, so my guess is that it’s closer to the 16.15 value.

    MO is the small blue object next to the large elliptical galaxy NGC 541 in the center of the image above. 541 is large and bright at magnitude 12.1 and makes an eye catching group with NGC 545 (mag 12.2) and NGC 547 (mag 13.2). The latter two galaxies make up Arp 308.

    HST MinkowskiObject.jpg
    (HST image)

    NGC 535 (mag 13.9) lines up with the 547, 545 and 541 galaxies in a straight line, making this group even more striking. There are a handful of fainter galaxies in the area as well, especially to the southwest. Interestingly, all three of the NGC elliptical galaxies mentioned above seem to be interacting with each other.

    Perhaps the distinctive blue color of MO makes it more difficult to see than an ordinary galaxy of its size and brightness, but I only have two observations so far – one with my 28” inch and one with Jimi’s 48 inch. I didn’t see it on a poor night with the 28 but saw it easily on an even poorer night with the 48.

    The first sketch is from the 28 inch, and note that I did see the small galaxy LEDA 86298 just to the south of Minkowski’s Object. I used 408x to 605x on a 21.57 night with poor transparency:

    Arp133N541, Arp308_N545 and 547_crop_28.jpg Arp133N541, Arp308_N545 and 547_crop_28_invert.jpg

    The next sketch, with the arrow pointing at MO, is from using Jimi's 48 inch at 487x on a 21.36 night with even poorer transparency. Note that seeing all three of the small galaxies next to NGC 541 was rather easy:

    Arp133_Minkowski's Object_48_crop.jpg Arp133_Minkowski's Object_48_crop_invert_flipped.jpg

    Finding MO’s position is easy – it’s the middle of three small galaxies located on the eastern edge of 541. Seeing this exotic object is the challenge, but one that should be within the capabilities of many observers on this list.

    Last edited by Howard B; December 6th, 2014 at 04:18 AM.
    28 inch f/4 alt-az Newtonian

  2. #2
    Join Date
    Feb 2012
    Nice galaxy chain along NGC 535/541/545/547 beside Minkowski's object. I visited the group several years ago with my 16" but did not try M. object. A few days before I revisited the group with the 27". Unfortunately with very bad seeing. I had difficulties to see LEDA 86298. Under normal circumstances with 17,3bmag an easy target. As you can imagine I could not detect Minkowski's object.

    16", 257x, NELM 6m5+
    Clear Skies, uwe

    27" f/4,2

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