This is Arp 297, the ngc 5754 galaxy group in Bootes. Somewhat oddly, Arp labelled it in the 'long filaments' section and comments that it has a 'Companion on arm has long tail extending westwards.'
Now on Arp's original plate there is no sign of a long tail certainly not extending westwards, so I was unsure quite what he was refering to. I decided to image the group last month when it was about as high as it gets around here. There is an interesting paper here:
iopscience.iop.org/1538-3881/126 ... 3_1257.pdf which discusses the system and shows a possible tail extending westward after extensive log mapping - the HST image of the group, shown in this paper with a rather small field, does not show much in the way of tails.
I took 30 x 3 minute exposures and had a lot of trouble with 'warm' pixels, as often happens in the summer. The whole group is faint and small and I had some seeing/resolution problems that night.
NGC 5752 is mag. 14.1, 5753 is mag. 12.8, 5754 is mag. 14.1 and 5755 is mag. 15.1, all pretty low surface brightness, too. My image shows some structure in the main spiral arms but some of the fainter ones are not visible and certainly no sign of the long tail extending westward.
I was about to consider it a figment of Dr. Arp's imagination, when I had a look on SKY-MAP.ORG and found this!
server5.sky-map.org/imgcut?surve ... _type=jpeg
Definitely signs of a very faint long tail extending Westwards (right), which just goes to show what a great observer Halton Arp is.
There are some interesting redshifts shown in Fig. 1 of the above paper. 5753 and 5755 show very similar recession velocities of around 9600km/s and 5752 and 5754 have velocities of around 4500km/s. One group is twice as remote as the other? I'd like to find redshift data on the tail but no luck so far.
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