Deep sky challenge
How to track down some of Cassiopeia’s most sneakily concealed crown jewels
Naked-eye observers might love Cassiopeia because it is so easy to spot in the sky, but most telescope users don’t pay the distinctive W-shaped constellation much attention. They tend to skip over or past it as they swing their instruments towards its neighbours, eager to see the ‘celebrity’ deep-sky objects around it.
Nearby Perseus has the stunning and famous Double Cluster, Taurus has the Pleiades (Messier 45) and Andromeda has the amazing Andromeda Galaxy (Messier 31). But it’s definitely worth taking the time to look a little more closely at Cassiopeia, the infamously vain queen of the sky, because if you do you’ll find a surprising number of attractive deep-sky objects hidden within the folds of her royal robes.
The star cluster Messier 103 might have been the very last object Messier put in his catalogue, but it’s far from the least attractive; it is one of the hidden gems of the night sky, but needs to be seen through as big a telescope as possible. If you’re lucky enough to find yourself at your telescope’s eyepiece on a beautiful dark night with no Moon or light pollution, the nearby Owl Cluster (NGC 457) is also worth a look.
Close to the naked-eye star Gamma Cassiopeiae, you’ll find not one but two swirly nebulae known as IC 59 and 63 – collectively the Gamma Cassiopeiae Nebula – but you’ll need your best eyepiece and perfect seeing to glimpse the dark lanes and knots of dust within these beautiful subtle arcs of misty light.
“You’ll need your best eyepiece and perfect seeing to glimpse the dark lanes and knots of dust within these beautiful subtle arcs of misty light”
1 Messier 103
The final object catalogued by the comet hunter Charles Messier, the 40-plus stars of this +7.4 arrowhead-shaped cluster are a beautiful sight in a large telescope’s low-power eyepiece.
2 Gamma Cassiopeiae Nebula (IC 59 and 63)
This close pair of crescent-shaped nebulae look very pretty in a large telescope’s high-power eyepiece, but any details or structure are drowned out by light pollution.
3 Pacman Nebula (NGC 281)
This bright nebula is nicknamed the Pacman Nebula after its resemblance to the arcade game character, but its fascinating interior details are only visible in larger telescopes.
4 NGC 663
This seventh-magnitude open cluster is 8,000 light years distant, but covers just 15’ of sky. Containing around 60 stars – most much fainter than seventh magnitude – it is best seen through a high-power eyepiece.
5 NGC 559
A challenge for large telescopes on dark, Moon-free nights, this magnitude +9.5 cluster is little more than a spray of faint stars barely 4.4’ across. It is also known as Caldwell 8.
6 Owl Cluster (NGC 457)
This cluster is one of the finest in the region. Large telescopes will resolve the triangle-shaped cluster’s compressed centre and three lines of fainter stars leading away from it.