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The Orion Nebula is far from the only object of interest along Orion’s sword
Tick the box when you’ve seen each one
1 NGC 1980
The south of Orion’s Sword is marked by open cluster NGC 1980. This appears to include mag. +2.8 Na’ir al Saif (Iota (f) Orionis) although in reality this is a foreground multiple star system with three components. Iota A is a spectroscopic binary. Two additional doubles help bring interest to this rather sparse open cluster. They are Struve 747 (mag. +4.8/+5.7, separation 36”, PA 223°) and Struve 754 (mag. +5.7/+8.9, separation 5.2”, PA 287°). The cluster appears 0.25° across and is an easy target for a small scope. Interestingly, foreground Iota is possibly a runaway star, the result of a collision between two binary star systems in the Trapezium Cluster (Theta1 (e ) Orionis). Other associated runaways are AE Aurigae and Mu (+) Columbae. Ĵ SEEN IT
2 M42
Our next target needs no introduction. M42, the Orion Nebula, dominates the southern half of Orion’s Sword. The nebula is an easy small telescope target, characterised by a bright kidney-shaped core called the Thrust, which contains a small open cluster known as the Trapezium. Two distinctive wisps of nebulosity sweep back from the Thrust and are named the Sail and, somewhat confusingly, the Sword. One of the fascinations with M42 is tracing these faint strands. Visually, the nebula is bright enough that you can see its green hue, typically associated with a low-probability electron transition in doubly ionised oxygen. M42 is about a degree across and lies at a distance of 1,344 lightyears, giving a physical dimension of 24 lightyears. Ĵ SEEN IT
3 M43
A dark triangular inlet into the Thrust on the northern edge known as the Fish’s Mouth connects with a dark lane appearing to divide M42 from M43, de Mairan’s Nebula. This is a distinctive, comma-shaped patch of nebulosity, dimmer than M42 at mag. +9.0. Like M42, M43 is a glowing HII region – a cloud of predominantly ionised hydrogen gas. If you imagine M43 as a circle, a dark cloud appears to clip out the eastern quadrant giving rise to the nebula’s comma shape. M43 has an apparent size of 20x15 arcminutes. An irregular variable, NU Orionis, sits at its centre and exhibits a small variability between mag. +6.8 and mag. +6.9. Ĵ SEEN IT
4 NGC 1977
Heading north up the sword brings you to a distinctive bent line
of three stars. These are relatively bright at mag. +5.2, mag. +7.3 and mag. +4.6 (east to west), although the dimmer, middle star, V358 Orionis, is slightly variable. This region is permeated by a diffuse reflection nebula known as NGC 1977. This has gained notoriety amongst astrophotographers because long exposures reveal a series of darker lanes crossing the nebula. Together these give the appearance of a stick figure in mid stride earning it the name the Running Man Nebula. Visually the nebula is fairly straightforward through larger instruments and it’s definitely possible to detect some of the darker lanes. However, the Running Man is a very tough challenge for the eye. Ĵ SEEN IT
5 NGC 1975
As we’ve already included NGC 1977, it seems only appropriate to point out that the Running Man Nebula is only one of three nebulae that go under the umbrella name of Sh2-279 (Sharpless 279). Technically this also covers our last target, NGC 1981, as well. NGC 1973 is the brighter patch of nebulosity surrounding the two pairs of stars to the north-northwest of the bent line described above. NGC 1975 is the northern ‘cap’ on the Running Man nebulosity. These regions are quite indistinct and don’t have any absolute divisions from the general NGC 1977 glow. It’s an interesting exercise with a low to mid-power eyepiece on a large scope to note just how much detail you can see in this region. Ĵ SEEN IT
6 NGC 1981
Open cluster NGC 1981 marks the northern end of Orion’s sword just as open cluster NGC 1980 (target 1) marks the southern end. Like its southern counterpart, NGC 1981 is quite sparse, but it’s larger, occupying an area approximately 0.5° across. Its brighter members shine between mag. +6.5 and mag. +7.5 and form an interesting pattern, which some liken to the shape of a crocodile. If you’ve never noticed that before, this is one of those moments when your view of NGC 1981 will change forever. The star HD 37129 marks the creature’s snout and HD 36670 the end of its tail. The stars in between describe its body with its front and back legs hanging towards the south. Ĵ SEEN IT