Deep Sky Object in Autumn
M72 & M73(Globular & Open Clusters in Aquarius)


Date & Time: M72: Nov 7 2021, from 19:35 to 20:03 JST(+0900), 4min.×8shots
M73: Nov 7 2021, from 20:09 to 20:29 JST(+0900), 4min.×6shots
Optical: Meade 25cm(10") Schmidt-Cassegrain with conversion lens (f=1600mm, F6.3)
with BaaderPlanetarium Moon&Skyglow filter
Auto-guided with Meade LX200 Equatorial & Lacerta M-GEN
Digital Camera: Nikon D810A
Location: Ooizumi, Hokuto city, Yamanashi pref.

Camera Settings: Recording Format...14bit CCD-RAW, converted to 16bit TIFF(3060×4080)
Device Size...15×20mm
Sensitivity...ISO4000, White Balance...Daylight


M72 (NGC6981) / Globular Cluster, type IX
R.A.20h 53m 30.0s (2000.0)
Dec.-12° 32' 00" (2000.0)
Apparent Size5.9'
Real Size100 light yrs.
Magnitude9.4
Distance60 thousand light yrs.
M73 (NGC6994) / Stellar Group
R.A.20h 59m 0.0s (2000.0)
Dec.-12° 38' 00" (2000.0)
Apparent Size3.0'
Real SizeN/A
Magnitude9.0
DistanceN/A
This image shows you two small Messier's objects paralleling in east-west direction at around a border of Capricornus and Aquarius.
M72 is a globular cluster with an apparent diameter of 6 arc minutes and about 9th magnitude. It hardly can be distinguished with normal stars through finder scopes so you may miss it without very cared searching. The cluster is positioned at 3.5 degrees SSE of epsilon Aqr.
And M73 is lying at 1.3 degrees east of M72. This Messier's object is registered as an open cluster, but the cluster has only four 11th magnitude fine stars. It's very delicate whether M73 can be regarded as an astronomical open cluster. You can appreciate the asterism like a very compact cluster through telescopes with a low magnifying power. It may be no wonder that Messier recognized the cluster as an open cluster.



M30
NGC288

Copyright(c) 2021 by Naoyuki Kurita, All rights reserved.
To top page To Deepsky in Autumn index Aquarius