Some Arps

Recent observations with my 16" under good conditions, SQM 21.6.

Arp 38, NGC 6412. The galaxy is visible already in the finder eyepiece. At 330x, the galaxy has a distinct core and its halo extends more the half of the way to the star to its SW. A threshold star on the same line farther SW is seen. The Arp companion at the N edge of the halo is clearly seen. It is hard to distinguish from a star due to seeing. The stubby arm leading SE and E is clearly seen. At times it continues to the enhancement near the edge of the halo straight E from the core, and at other times this enhancement is clearly separated from both the core and the arm.

Arp 81 (NGC 6621-2) is seen vaguely in the finder eyepiece as a strongly elongated patch. At 330x, the view is very detailed. The companion is elongated roughly EW, pointing at the nearest star. There is an enhancement between it and the core that occasionally exhibits a sharp center, possibly a superimposed star. On the opposite side of the core is another bright enhancement that at the first glance makes the galaxies look like a triple system. The main part of the galaxy extends farther NNW and then curves sharply into an arm that runs almost as far SSE as the mentioned nearest field star. There is a broad proximal and a very thin, sharp distal enhancement in this arm.

Arp 109, MCG+12-15-17 and -18. Located next to IC 1146. IC 1146 is almost round. Also in the field is MCG+12-45-20. It is comparatively sharp, thin, and elongated NS. Of the two Arp galaxies, MCG+12-15-18 is the larger, brighter, and more conspicuous. However, both are immediately seen at 330x. MCG+12-15-17 at times appears elongated to the NW of the core, and at other times there appears to be a very small spot, almost indistinguishable from a threshold star to the NW and forming a right triangle with the field star to the W. This seems to be traces of the arm “repelled” by MCG+12-15-18.

Arp 169. At 330x three components are diminishing from NW to SE. The first one, NGC 7236, is concentrated and prominent. The second, NGC 7237, appears larger but much fainter and more diffuse, with no concentration. The third one, NGC 7237C, is like a threshold star. There is a common halo at least around the first two components.

Arp 278 (NGC 7253-A). Two very unequal edge-on galaxies almost touching at an angle with their E ends. A double star in between. The tapered W end of the larger EW component bends slightly S.