BINOCULAR TOUR

This month’s wide-field wonders include Barnard’s E and two globular clusters

1. 3, 4 and 5 Aquarii

10x 50

4 and 5 Aquarii comprise a very easy double star, at mag. +5.5 and mag. +6.4 respectively, separated by 13 arcminutes. This is a line-of-sight pairing, not a true binary star. A degree or so to the northwest you will see a brighter orange star. This is the slightly variable (mag. +4.4 to +4.5) 3 Aquarii. If you enjoy looking at coloured stars, scan the region 5° northwest of 3 Aquarii.  SEEN IT

2. M2 10x 50

The globular cluster M2 forms a right-angled triangle with Sadalsuud (Beta (β) Aquarii) to the south and Sadalmelik (Alpha (α) Aquarii) to the east. It stands out, even in small binoculars, in an otherwise sparse region of sky, looking exactly as Charles Messier described it: “a nebula without stars”. Try averted vision by directing your gaze to 24 Aquarii, 1° east of the cluster, and you might notice that it appears slightly oval.  SEEN IT

3. M15

10x 50

Our second globular cluster, M15, is another easy target. Find it by extending a line from Biham (Theta (θ) Pegasi) to Enif (Epsilon (ε) Pegasi) another 4° northwest. It appears rounder and brighter than M2, but do not expect to see it even half as wide (18 arcminutes) as planetarium programs suggest. Most of its stars are densely concentrated into the core so only the central third of it is visible in 50mm binoculars.  SEEN IT

4. Eta Aquilae 10x 50

In 1784, the York-based astronomer Edward Piggott announced the discovery of a star that varied in brightness: Eta (η) Aquilae. This is one of the brightest

Cepheid variables (mag. +3.5 to +4.4, with a period of 7.18 days), and it was found a month before his collaborator, John Goodricke, discovered the variability of Delta (δ) Cephei, the star that gives that class of variable star its name.  SEEN IT

5. Barnard’s E

10x 50

This is one of the easiest dark nebulae. You’ll find it 1° west of Tarazed (Gamma (γ) Aquilae). It’s actually a pair of nebulae, B142 and B143, which stand out against the star-rich Milky Way background, making them easy to find and identify. Choose a dark transparent night if this is your first attempt at dark nebulae, and the obscuring gas and dust will appear either as an uppercase ‘E’ or an underlined ‘C’.  SEEN IT

6. The Saturn Nebula, NGC 7009 15x 70

You’ll need dark, transparent skies for this nebula, but it is easy to locate: identify Nu (ν) Aquarii and it is 1.3° due west. NGC 7009 will look like a defocused star but, even if you use a UHC (Ultra High Contrast) or O-III (Oxygen) filter, your binoculars won’t show the elongation that gives it its name.  SEEN IT

✓ Tick the box when you’ve seen each one