Deep Sky Object in Summer
IC4665 (Open Cluster in Ophiuchus)

Click on image to enlarge

Date & Time: Jul 25 2025, from 21:35 to 22:39 JST(+0900)
Composed 13 shots with 5 minutes exposed
Optical: BORG 67FL with conversion lens (f=324mm, F4.8)
with IDAS LPS-P1 Light-pollution suppression filter
Auto-guided with TAKAHASHI EM-200 Equatorial
Digital Camera: Canon EOS 6D (Remodeled)
Location: Hitachi-oota city, Ibaraki pref.

Camera Settings: Recording format...14bit CCD-RAW, converted to 16bit TIFF(5472×3648)
Device Size...36×24mm, Sensitivity...ISO1600


IC4665 / Open Cluster, type c, III 2 m
R.A.17h 46m 18.0s (2000.0)
Dec.+05°43' 00" (2000.0)
Apparent Size41.0'
Real Size11.8 light yrs.
# of Stars30
Magnitude4.0
Distance990 light yrs.
IC4665 is a very sparse open cluster scattered at about a degree north of beta Oph. The cluster has a apparent diameter of about 40 arc minutes, you can enjoy that with a portable binocular. This IC4665 has only 30 member stars. Outward looks of the cluster would be almost same as the Milky Way flowing just next on east. But the cluster has a sufficient big size; we can take it only with small photo lenses easily.



NGC6940
IC4756, NGC6633

Copyright(c) 2025 by Naoyuki Kurita, All rights reserved.
To top page To Deepsky in Summer index Ophiuchus