Object name: ARP331

Designation(s): ARP331, NGC0373, NGC0375, NGC0379, NGC0380, NGC0382, NGC0383, NGC0384, NGC0385, NGC0386, NGC0387, NGC0388,

The Pisces Cloud is 29 galaxies in Pisces galaxy cluster though common usage seems to refer just to the C2 group which is Arp 331. How many galaxies Arp considered part of his chain seems to vary with the source. Most say the 8 listed below excluding 373, 375 and 388 but others say 12 or more. It just depends on when you stop counting and how far east or west of the bright vertical chain you venture. If those I list Seligman leaves out 373 saying it is too far west.

Hubble classed this group as \"Group Character: Chains of galaxies\". It is also known as Zwicky cluster 0107.5+3212. The chain is too large for the FOV of the 200\" so the photo Arp uses comes from 48\" Schmidt camera. It appears to be a very short exposure as it only picks up the cores of the galaxies making them look a lot further apart than they do in my image. Arp\'s comment: \"Symmetry around large central galaxy.\" This may be a clue as to which galaxies he considered part of his object.

Galaxies north to south with discoverer and date of discovery. Galaxies north to south with discoverer and date of discovery. Independent redshift is noted by ind. RS indicates a redshift distance. Both are in millions of light-years.


NGC 379 S0 208 ind, 241 RS William Herschel September 12, 1784
NGC 380 E2 208 ind, 189 RS William Herschel September 12, 1784
NGC 383 SA0 LERG* 208, 220 RS William Herschel September 12, 1784
NGC 382 E, 234 ind, 226 RS Bindon Stoney November 4, 1850
NGC 387 (east of 382) no class no ind 202 RS Lawrence Parsons December 10, 1873
NGC 386 E3, no ind, 240 RS Bindon Stoney November 4, 1850
NGC 375 E2, no ind, 254 RS Lawrence Parsons December 1, 1874
NGC 385 SA0, 208 ind, 214 RS Bindon Stoney November 4, 1850
NGC 388 east of 385 E3, no ind, 235 RS Bindon Stoney November 4, 1850
NGC 373 E, no ind, 238 RS John Dreyer December 12, 1876
NGC 384 E3, no ind, 180 RS Bindon Stoney November 4, 1850

All carry this NED note:
Faint compact member of the Group C2 of elliptical galaxies forming one of the four prominent condensations.

So what about that lone spiral above NGC 375 (UGC 679). Include it and you get an even dozen that some writers say is the count. Oddly the MCG catalog lists it as being NGC 375! Is it a member of the group though not mentioned by Arp? Looks like it may be. NED says it\'s likely about 214 million light-years away, only about 6 million more than the rest, and redshift puts it at 220 million light-years which is in close agreement as well.

The image is full of orange \"stars\" that are really galaxies. For instance just off the east end of the blue spiral are two of these star-like galaxies. One is slightly above and left, it is very orange. A bit closer and below is a yellow-white \"star\" that is also a spherical galaxy. I have no redshift or other distance indicator but suspect they are part of the same group, just smaller members.

I had to move the field further north than I wanted due to the 6th magnitude star. When I centered everything it was out of the field but sending in some nasty ghosts. The only way to get rid of the worst of them was to move it into the FOV. For some reason, my filters scatter more green and blue than red light so even though it is a K0 star it has a rather cyan halo from the excess green and blue. I didn\'t try to fix this.

Many galaxies in the image I didn\'t mention had redshift data. All of which indicate they are members of this group. Far more either had no redshift data or weren\'t in any catalog. This area hasn\'t been covered by SDSS.

NGC 390 is just one of two stars I\'ve listed as a double star in the annotated image. Guillaume Bigourdan saw it on November 19, 1884 recording it as \"very faint, very small, stellar. Unfortunately, while these two stars are nearby his position fits neither well enough to tell which he was seeing. Most likely the upper one so that\'s where I put the label. It itself is a double star which might have made it appear slightly fuzzy. Some say PGC 4021 further east and a bit north is what he saw. That, though, just stretches the NGC position too much. Certainly doesn\'t fit his stellar description either.

Arp\'s image with the 48\" Schmidt telescope:
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp331.jpeg

*LERG stands for Low Excitation Radio Galaxy

14\" LS200R @ f/10, L=5x10\' RGB=2x10\'x3, STL-11000XM, Paramount