We explore the best celestial sights around Aries, Pisces and Triangulum
1. NGC 821
Recommended equipment: Large telescope
Our starting object is mag. +11.3 NGC 821, an elliptical galaxy in the extreme southwest corner of Aries, 12.5° south of mag. +2.0 Hamal (Alpha (α) Arietis). A mag. +9.2 foreground star lies a fraction to the west-northwest of the galaxy’s centre. Even in a 250mm scope, NGC 821 is little more than a smudge, 1.4×0.6 arcminutes across and elongated from southwest–northeast. A 300mm scope doesn’t pull a great deal more from this galaxy. Start off with medium magnification to reveal that the galaxy seems to concentrate towards a star-like nucleus. This is particularly evident at higher magnifications, but increased power won’t do the outer halo any favours.
2. NGC 772
Recommended equipment: Small/medium or Large telescope
We head north towards the three stars that form the most recognisable part of Aries to find the unbarred spiral galaxy NGC 772. This shines at mag. +11.1 and unlike NGC 821 is visible in smaller scopes. It lies 1.4° to the east of Mesarthim (Gamma (γ) Arietis) and shows as an oval glow with a defined core that brightens to a star-like nucleus through a 150mm scope, and appears distinctly mottled with larger apertures. A 300mm scope shows an object 3.5×1.5 arcminutes in size. The galaxy’s seemingly diminutive appearance from Earth is misleading. Located 130 million lightyears from us, this object is estimated to be around twice the size of our own Milky Way Galaxy!
3. M74
Recommended equipment: Small/medium or Large telescope
Heading next door into Pisces, 2.4° west of the western Aries border we find face-on spiral M74. The guide point here is to imagine a line from Hamal to Sheratan (Beta (β) Arietis). Extend it almost twice that distance again to reach mag. +4.0 Eta (η) Piscium; M74 lies 1.3° to its east-northeast. A small instrument shows a slightly elongated patch of light 6 arcminutes across that gently brightens towards the centre. A 250mm scope reveals a larger patch, 8 arcminutes across with more pronounced elongation with an east–west orientation. The core appears slightly off-centre. A large aperture reveals a prominent granular centre and a beautifully mottled outer halo, full of faint detail.
4. NGC 697
Recommended equipment: Small/medium or Large telescope
We return to the Aries grouping of three main stars, Hamal, Sheratan and Mesarthim, for NGC 697. It’s located 1.7° to the northwest of Sheratan, 0.3° to the northeast of the double star 1 Arietis, whose component magnitudes are +5.8 and +7.1. Presumably due to a mix-up somewhere down the line, NGC 697 is also known as NGC 674. A small scope shows an object with a definite core around 1 arcminute across, which grows only slightly through a 250mm scope, which also reveals an elongated core. A 300mm instrument shows a marginally larger galaxy of 2.0×1.0 arcminutes, elongated east–west.
5. Collinder 21
Recommended equipment: Small/medium or Large telescope
We head north out of Aries for the open cluster Collinder 21. It is located 4.6° to the north of NGC 697 and 0.6° north of mag. +6.9 HIP 8490 in Triangulum. At 9 arcminutes across and mag. +8.2, a small telescope won’t have any trouble finding the stars that make up this tight group. Its brightest stars form a shape reminiscent of the semi-circular constellation Corona Borealis and range from eighth to 11th magnitude. Pretty though it appears, Collinder 21 isn’t a true cluster at all but simply an asterism, a line-of-sight arrangement of stars. About 15 stars populate the ‘cluster’ zone.
6. NGC 672/IC 1727
Recommended equipment: Small/medium or Large telescope
There are several galaxies surrounding Collinder 21, including spiral galaxy NGC 672 located 0.5° to the northwest. Shining at mag. +11.1, it is visible in small telescopes as a featureless elongated glow, brightening at its core. A 250mm scope shows an asymmetrical outer envelope measuring 4×1.5 arcminutes. Larger apertures reveal its core to be uneven in brightness and almost knotted in parts. NGC 672 forms an interacting pair with IC 1727, an irregular galaxy of similar apparent size immediately to its southwest. At mag. +11.6, IC 1727 is virtually invisible to smaller scopes. Larger instruments just show a glowing patch 3×1.5 arcminutes in size.
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