Arp 23 in Canes Venatici is a pair of one-armed spirals, the larger NGC 4618 and the smaller NGC 4625. This pair is also KPG 349. I first saw the Herschel 400 object NGC 4618 with 4” a few years ago. It is actually two Herschel objects, because he cataloged the core and the large enhancement in this galaxy separately. Vorontsov-Velyaminov adopted a similar view, cataloging the core as his #73b and the arm as 73a.
Recently I have sketched the entire field as it appeared in my 12” SCT. The galaxies could indeed be framed at a magnification that revealed their structure. I used the 8-24 mm Pentax zoom, which gives nominally 125-375x in this telescope and has an approximately constant true field within its range. In addition to the main part of the arm in NGC 4618, the proximal (E) and distal (W) parts of that arm were seen as detached enhancements. SQM 21.78.
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