NGC 1605
Pan-STARRS image of NGC 1605
Observation data (J2000 epoch)
Right ascension	04h 34m 58.4s[1]
Declination	+45° 16′ 09″[1]
Distance	7,990 ± 320 ly (2,449 ± 98 pc)[2]
Apparent magnitude (V)	11.0[3]
Apparent dimensions (V)	5.0′ × 5.0′[3]
Physical characteristics
Mass	623[4] M☉
Estimated age	400±50[4] Myr
Associations
Constellation	Perseus
See also: Open cluster, List of open clusters

NGC 1605 is an open cluster of stars in the northern constellation of Perseus. It was discovered by German-British astronomer William Herschel on December 11, 1786.^[5][6] This cluster is located at a distance of approximately 8,000 ly (2,449 pc) from the Sun.^[2] It spans an angular size of 5.0′ × 5.0′ with an apparent visual magnitude of 11.0.^[3]

Observations

This cluster has a low concentration with a Trumpler class of III 2 m.^[7] It is estimated to have 623^[4] times the mass of the Sun with a core radius of 2.49+0.27
−0.41 pc.^[2] The cluster is drifting closer to the Sun with a line of sight velocity component of −15.27±1.35 km/s. It is a member of the young thin disk population of the Milky Way.^[4]

In 2021, D. Camargo presented results that suggested NGC 1605 is actually a binary open cluster system. The data showed two distinct stellar populations in the region: NGC 1605a with an age of 600 Myr and NGC 1605b at an age of 2 Gyr. This large age difference seemed to indicate a close encounter between two clusters that resulted in tidal capture. The presence of possible tidal debris appeared to support this hypothesis.^[8] However, a 2022 study of Gaia 3 data contradicted this finding, suggesting the apparent difference was the result of contamination by field stars.^[9][10]

The open cluster Can Batlló 1 may be located less than 330 light-years (100 pc) from NGC 1605.^[9]

References