Arp 23 - NGC 4618 & NGC 4625
March 31, 2026
Arp 23 is a pair of interacting spiral galaxies in the constellation Canes Venatici, about 25 million light-years from Earth. NGC 4618 is classified as a one-armed barred spiral (type SBm) — one of the few galaxies known to possess a single prominent spiral arm, giving it a distinctly asymmetric appearance. Its smaller companion NGC 4625 is a dwarf spiral galaxy connected by faint tidal bridges visible in deep UV and optical imaging.
The pair’s interaction has likely driven the unusual morphology of NGC 4618’s single arm. Deep ultraviolet observations have revealed that NGC 4625 possesses extended spiral arms reaching far beyond its visible disk — evidence of the gravitational interplay between the two.
Processed by Malcolm.
Acquisition Details
Telescope: RC12 | Camera: ZWO ASI 6200MM | Mount: 10Micron GM2000
| Filter | Frames | Integration |
|---|---|---|
| L | 120 × 120s Bin1 | 4 hr |
| R | 60 × 120s Bin2 | 2 hr |
| G | 60 × 120s Bin2 | 2 hr |
| B | 60 × 120s Bin2 | 2 hr |
| Total | 10 hours |
Calibrated and processed in PixInsight.