Arp 103

ARP 103 2015 July 22

Object:            ARP 103

(MCG+8-31-3 Zwicky’s Triplet)

Date:               2015 July 22


Peculiarity:    Elliptical connected to spirals.
Constellation:           Hercules Time & altitude: 00.20 UT     55º
Catalogue data: Seeing (5 high):                               3/5
            R.A:                16h 49m Transparency (5 high):                   4/5
            Dec:                +45º 28 Telescope:     0.5m f4.1 Dob.
            Magnitudes:    16.0, 15.7 & 15.2 Eyepiece:      8mm Ethos      x260
            Galaxy size (mins):  0.8 x 0.7 Filters:            None.


First session with newly aluminised mirrors. Arp 103 aka Zwicky’s Triplet is half a degree S of 52 Her. NGC 6241 (14.8m) is in the field but is not part of the Arp object. It is slightly oval with the major axis aligned EW.

Zwicky’s Triplet is MCG+8-31-3 (16.0m) and PGC 59062 (15.2m) close together and MCG+8-31-3A (15.7m) a bit N. All three seen readily with DV despite their faintness. I could not separate the MCG/PGC pair however. The NE side of this pair has a clear boundary but on the opposite side less so, a bit like a comet coma.  MCG+8-31-3A is a tiny but conspicuous round spot.  I saw no trace of the thin tidal tail in Arp’s photo which runs from the S pair towards the 3A galaxy to the N.