Fall / Autumn – C14, Double Cluster in Perseus (DSOMG)
| Target | Type | R. A. | Dec. | Constellation | Magnitude | Size |
| C14 (NGC 884) | Open Cluster | 02h 22m 23s | +57° 07′ 00″ | Perseus | +6.1 | 18.0 arcmins |
Overview
Despite being counted as one object in the Caldwell catalog, there are two actual objects here, as the name suggests. NGC 884 (data above) is the uppermost in the picture, while NGC 869 is below it.
These are both visible to the naked eye, which is why they’ve been known about since well before telescopes and have no discoverer, although they were first recorded by Hipparcos in 130 BC.
They’re close to each other – only a few hundred light-years apart – but about 7,500 light-years away from Earth. NGC 869 is the more massive of the two, with approximately 4,700 solar masses versus the 3,700 for its partner. With their associated halo of stars, their combined mass is >20,000 solar masses.
They’re believed to be about 14 million years old, making them mere children when compared to the 75-150 million years of the Pleiades.
Unusually for most of the objects we look at, this pair of clusters is speeding towards Earth at 24 miles (39 km) per second.
Finder Charts
The first sky chart, from SkySafari 6, shows the view looking south at 10 pm in the middle of December. The moon and planets are not shown and stars are only shown to magnitude 5.0.
Although at its highest at that time in the winter, this a circumpolar object for most northern latitudes and so never sets and is visible all year around.
Visible to the naked eye under dark skies, and easily so in binoculars or a low-powered telescope eyepiece, the starting point for finding it is the obvious ‘W’ of Cassiopeia, circled orange in the chart.
Zooming in to show Cassiopeia on the left and Perseus on the right, we find C14 (marked as NGC 884 in the charts) about two-thirds of the way along a line from Ruchbah in Cassiopeia to Miram in Perseus. Both of these stars are bright and easily visible under all except the most light-polluted skies.
This last finder chart shows stars to magnitude seven. These are easily visible in magnifying finderscopes and binoculars.
In reality, you won’t need the locator stars shown in the chart, V520 Persei and HD 14143 because the object itself is just as bright and impossible to mistake.
Now you’ve found this double cluster, are you ready for one of the night sky’s most impressive sights?
Individual Telescope Views
The following views will help you find C14 in different telescope types by presenting the images as your telescope will show them. The first image is with a black sky and white stars, the second picture is the same image but presented in inverse monochrome. Black stars on a white background is often easier to use at the telescope. Each image can be clicked on for a full-screen version. Stars are shown to magnitude 10.0 and the stars V520 Persei and HD 14143 are visible midway between the center and western edge of the 1.5° field of view circle.
Upright View – This is what your eyes see unaided and through a reflex or red-dot finderscope
Upside-down view – This is what reflectors and magnifying finders show, and refractors / Cassegrains without a star diagonal
Mirrored View – Refractors and Cassegrain models with a star diagonal show this view
Observation
Pull this hazy patch of sky into focus inside a 1.5° – or larger – field of view and be prepared to have your breath stollen away with its beauty. Each cluster is over half a degree in diameter, making the whole object twice the width of the full moon.
At lower magnifications, the eastern NGC 884 reveals more than 60 individual stars covering the gamut from bright to very faint. You won’t fail to see a handful of more orange lights against the background of largely blue-white stars.
NGC 869 is the smaller of the two, but it’s a close run thing and you may need some time to convince yourself of this. The stars here are more tightly packed in to their space. At its heart are two brighter stars but, as with NGC 884, it’s possible to count several dozen fainter members.
PDFs for Printing
Each of the star maps above is reproduced as a pdf below. Each star map has a number in [square brackets] beneath it which corresponds to the file number below. If you want image [C14-1], for example, click the ‘download’ button next to it below and you’ll be able to open it as a printable pdf.