Lie back and look straight up as Andromeda is this month’s hunting ground
1. NGC 752 and 56 Andromedae
Recommended equipment: 10×50
Put mag. +3.0 Beta (β) Trianguli at the south of the field of view and NGC 752 should appear near the north, just to the left of a close pair of 6thmagnitude orange stars (56 Andromedae). Unusually, the stars are yellowish (we normally expect hot blue-white stars in an open cluster), and this hints at its great age: nearly two billion years old! You should be able to resolve at least a dozen of these stars.
2. M31
Recommended equipment: 10×50
Start with the mag. +2.1 yellow star Mirach (Beta (β) Andromedae) at the southeast of the field of view and find mag. +3.9 Mu (μ) Andromedae toward the other edge. Place Mu where Mirach was and the elliptical shape of M31 will be where Mu was. From a dark site you should notice that the galaxy extends about halfway across the field of view, and you may also see the two companion galaxies, M32 and M110.
3. The Home Plate
Recommended equipment: 10×50
Locate the little triangle of mag. +4.6 Theta (θ), mag. +5.2 Rho (ρ) and mag. +4.5 Sigma (σ) Andromedae and pan 2.5° (about half a 10×50 field of view) northwest from Theta, where you’ll find an irregular pentagon of yellowish 7th-magnitude stars. It covers an area about 0.5° x 0.75° and looks just like the home plate on a baseball field, a similarity for which the asterism is named.
4. NGC 7662
Recommended equipment: 15×70
Identify mag. +4.3 Iota (ι) Andromedae and scan 2° west to 13 Andromedae. You’ll find NGC 7662 – also known as the Blue Snowball Nebula – half a degree to the south-southwest. It looks like an 8th-magnitude star, but 70mm (or larger, if you have them) binoculars should help to bring out the blue-green tint that distinguishes it from the surrounding, mostly white, stars. You may find that its colour is more obvious if you defocus your binoculars very slightly.
5. NGC 7686
Recommended equipment: 10×50
Find mag. +4.1 Kappa (κ) and mag. +3.9 Lambda (λ) Andromedae and extend a line joining them the same distance northwards, to an obvious pair of orange stars, the brighter of which is mag. +6.2. Relax your eyes and the 15-arcminute diameter glow of the background cluster will become visible, but you’ll need to switch to larger binoculars if you want to be able to resolve more than another three individual stars.
6. Northwest Andromeda starfield
Recommended equipment: 10×50
If you like coloured stars, you’ll love this bit of sky. In a region of less than 4°, you’ll see seven 5th-magnitude stars from the brilliant blue-white of EW Lacertae, to the yellow-white of 7 Andromedae and the more orange 11 And, 3 And and V424Lac, to the sultry orange-red of 4 And and 8 And. It’s all against a glorious Milky Way background!