Arp 281

Arp 281 2019 May 22

Object:   Arp 281 (NGC 4631 & 4627) Date:               2019 May 22
Peculiarity:  Double galaxies with infall and attraction.
Constellation:           Canes Venatici Time & altitude:        23.15 UT     56º
Catalogue data: Seeing (5 high):                               3/5
            R.A:                12h 42m Transparency (5 high):                   4/5
            Dec:                32º 32 Telescope:     0.5m f4.1  Dob.
            Magnitudes   9.8 and 13.1 Eyepiece       17mm Ethos              x120
            Galaxy size (mins)   16 x 3 Filters:            None


This is a stunning object, reminiscent of M82 (Arp 337) or, more fancifully, the debris cloud as the Nostromo detonates near the end of Alien. NGC 4631 is reckoned to be an open barred spiral viewed edge-on. It is elongated 7:1 aligned EW. The full length visible is about 10 or 11 arcmins. The W end narrows and tapers to a point. There is a dark lane (or less-bright patch?) midway along the taper. The E end is squared off. There is a star midway just off the N edge. Working E from this star are two bright knots and then a dark lane. The whole galaxy is mottled and grainy, suggesting more structure at the limit of visibility. 4627 is just a misty oval glow. Overall the 17mm eyepiece gives much the better view as compared to the 8mm. The object does not seem to respond well to more magnification.