Arp 18

ARP 18 2015 May 13

Object:            ARP 18   (NGC 4088) Date:               2015 May 13
Peculiarity:    Spiral with detached segments.
Constellation:           Ursa Major Time & altitude: 00.00 UT     59º
Catalogue data: Seeing (5 high):                               3/5
            R.A:                12h 06m Transparency (5 high):                   3/5
            Dec:                +50º 32 Telescope:     0.5m f4.1  Dob.
            Magnitude:    10.5 Eyepiece:      17mm Ethos    x120                                       8mm Ethos    x260
            Galaxy size (mins):     5.8 x2.3 Filters:            None.


A gem! More impressive than M109 lying 3º to the N. The 17mm eyepiece gives the better view. Elongated NE-SW. Lots of structure suggests an inclined spiral with a warped disk. There is a large core surrounded by dark lanes and mottling all through the halo. The detachment of the ‘detached segment’ was not really seen however.

NGC 4085 (13.0m, 3’ x 1’) is easily visible in the same field 11’ S of 4088 but surprisingly is not part of the Arp Atlas object. It is like a ghost or reflection of 4088. It is an irregular tapered patch elongated EW and narrowing to the E.