NGC 1342 in Perseus

November 2026 - Nebula and Cluster of the Month

The nights have drawn in now, and plenty observing time is theoretically abundant. If it wasn’t for the weather. There’s not much that we can do about that, so let’s have a look at an object that would be nicely placed for observing in November if only it wasn’t for the cloud and the slashing rain.

The open cluster NGC 1342 lies in the southern half of Perseus, 5.7° south-east of the famous variable star β Persei (Algol). At magnitude 6.7, some observers have claimed naked-eye visibility, but for me that stretched the bounds of credulity. It may be bright, but that brightness is spread over a diameter of 17’ – over half the diameter of the full moon. It is not visible to the naked eye, but 10x50 binoculars will have no problem showing a patch of light with a few resolved stars of eighth and ninth magnitude.

It was first spotted by our old friend William Herschel on the night of 28 December 1799. He described it as A cluster of coarsely scattered large stars, about 15’ diameter. A description which stands well today. He placed it in his Class VIII (Coarsely scattered clusters of stars) as 88 H.VIII. It was the last entry he would make in that class and is the final entry (numerically) in Herschel’s great catalogue (though it was not the last object to be entered in that catalogue).

It is a well-studied cluster and the most recent investigation¹ into it concluded that it lies at a distance of 645±42pc (2104±137 light years) and that it is 1000±50 million years old – so would be described as an intermediate-age cluster. The metallicity is 0.72 that of the Sun, not especially metal-deficient, but indicating that the cluster formed outside the ‘solar circle’, which is defined as the approximate orbit of the sun around the galactic centre. Different parts of the Galaxy contain different proportions of material out of which stars form, and the metallicity gives an indication of where this might have been for a given cluster (or individual star). NGC 1342 shows evidence of forming in the Galaxy’s thin disc, but further out than the Sun’s orbit.

Estimates of the cluster’s Trumpler class are reasonably consistent. In 1966, the Czech astronomer Jaroslav Ruprecht (1931—2011) classed NGC 1342 as type III3p (detached with no noticeable concentration, mix of bright and faint stars, poor (<50 stars), whereas Archinal & Hynes ² rate it as III3m, increasing the membership of the cluster to between 50 and 100.

More recent measurements via data from the European Space Agency’s Gaia mission has increased the membership (defined as those stars whose probability of membership is greater than 50%) to 799. This is truly a rich cluster.

Gaia’s data has also proved beyond any doubt that NGC 1342 is a real, gravitationally-bound cluster of stars and not a mere line-of-sight effect.

A small telescope shows a group of stars 17’ across, stars of eighth and ninth magnitude with a grainy background of unresolved fainter stars. With the membership count now nearing 800, it’s fair to assume that the member stars probably reach down to magnitude 21 at least (this is the approximate magnitude limit for Gaia).

Larger telescopes, of course, reveal more and fainter stars. I made a necessarily quick observation of NGC 1342 with my 12” (300mm) Newtonian reflector and found a loose cluster of both bright and faint stars. The cluster seemed to be arranged in a loose rectangle within the bounds of which I counted about forty stars. There is a prominent straight line of stars at the southern end of the cluster. On the western edge of the cluster, there is a wide double star which I later identified as HD 275505, magnitude 10.4. The brightest star in the cluster is magnitude 8.4 HD 21773. Using the distance to the cluster (645pc), it is possible to calculate the absolute magnitude of this star, which works out at magnitude -0.7, some 5.4 magnitudes brighter than the Sun.

NGC 1342 makes a fine sight in a small or moderate telescope, and it is worth a moment of your time.

Patrick Maloney

Object	RA	Dec	Type	Magnitude
NGC 1342	03h 31m 36s	+37° 22’	Open cluster	6.7

Reference:

1. A Comprehensive Study of Czernik 41 and NGC 1342 Using CCD UBV and Gaia DR3 Data, Tanık Öztürk, B., Bilir, S., Yontan, T., Plevne, O., Ak, T., Ak, S., Canbay, R. & Banks, T. The Astronomical Journal, 170(3), 164 (2025)
2. Star Clusters, Brent Archinal & Steven Hynes, Willman-Bell, 2003

If you'd like to try out the Clear Skies Observing Guides (CSOG), you can download observing guide for the current Cluster of the Month without the need to register. CSOG are not associated with the Webb Deep-Sky Society but the work of Victor van Wulfen.