Moth Nebula (Sh 1-89) & Cluster IC 1369

Sh 1-89, IC 1369: Planetary Nebula and open cluster in Cygnus; 500 mm Cassegrain f=3625 mm f/7.2; SBIG STL11K; 260-40-40-40 min LRGB; Bernese Highlands; © 2015 Radek Chromik


The open cluster IC 1369 was discovered on 27th April 1891 by the Danish astronomer Frederick Pechüle using the 11 inch Merz refractor at the Copenhagen Observatory. Dreyers description «small nebula cluster of stars of 13 mag» suggests that he thought to see a faint nebula in the cluster. [277, 313]

While searching the photo plates of the «Palomar Observatory Sky Survey» made with the 48 inch Schmidt telescope, the American astronomer Stewart Sharpless came across the nebulae Sh 1-89 and published it in 1953 in his first catalog of emission nebulae. [309] In his second catalogue of 1959 the nebula was classified as PN and removed. In 1967 the nebula was classified as type 3 (ratio of major to minor axis) planetary nebula by Hromov and Kohoutek and received the designation PK 89-0.1. [310, 391]

Physical Properties of Sh 1-89

Sh 1-89 is a small bipolar planetary nebula. The distance is estimated to be 1959 pc. [145] The visual apparent brightness is 14.5 mag. [149]

«Strasbourg-ESO Catalogue of Galactic Planetary Nebulae» Acker et al., 1992 [141]
DesignationsPN G089.8-00.6: Sh 1- 89, PK 89-00.1, ARO 357, VV' 544
Right Ascension (J2000.0)21h 14m 04s
Declination (J2000.0)+47° 44' 28"
Dimensions 35." (optical)
Distance 2.0 kpc
Expansion Velocity 7.5 km/s (O-III), 16. km/s (N-II)
C-Star DesignationsAG82 423
C-Star Magnitude19.7 mag (B filter)
DiscovererSHARPLESS 1959

Physical Properties of IC 1369

The open cluster IC 1369 is of Trumpler type I1m. Employing the Gaia DR2 coordinates, parallaxes, and proper motions, 143 cluster members are found having cluster membership probabilities ≥ 0.75. The hottest stars of the evolved main sequence are of spectral class B9. Distances, determined by two methods based on the Gaia parallaxes, are 3280 and 3370 pc with an uncertainty of 400–500 pc. The cluster age is found to be between 300 and 350 million years. Among the cluster members six red giants of spectral classes G5–G8 and luminosities II–III, 17 Am stars, one Ap star, and one B5 blue straggler were identified. [424]

Revised+Historic NGC/IC, Version 22/9, © Dr. Wolfgang Steinicke [277]
DesignationIC 1369
TypeOCL (I1m)
Right Ascension (J2000.0)21h 12m 09.0s
Declination (J2000.0)+47° 46' 00"
Diameter5 arcmin
Visual magnitude8.8 mag
Metric Distance2.100 kpc
Dreyer DescriptionS neb Cl of st 13m
Identification, RemarksOCL 204

Finder Chart

The planetary nebula Sh 1-89 and open cluster IC 1369 are located in the constellation Cygnus. The open cluster is useful to identify the exact position of the PN as it is located about half a degree east of it. The best observation time is from March to December.

Finder Chart Moth Nebula (Sh 1-89) & Cluster IC 1369
Moth Nebula (Sh 1-89) & Cluster IC 1369 in constellation Cygnus. Charts created using SkySafari 6 Pro and STScI Digitized Sky Survey. Limiting magnitudes: Constellation chart ~6.5 mag, DSS2 close-ups ~20 mag. [149, 160]

Visual Observation

Description pending ...

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