M41 (NGC 2287), open cluster, Canis Major
50x: Rich, sprawling cluster south of Sirius; bright stars forming curved lines. Loses some of its impact in a big reflector; looks better in a smaller wide-field scope.
92x: Bright stars, loosely concentrated. Arranged in a wavy “cross” shape, like a flattened hour-glass. Bright orange star near centre.
M42 (NGC 1976), Orion Nebula, emission nebula, Orion
Impressive at all magnifications – and in all scopes, large and small. In the SP-102, I always thought it took on the appearance of a swooping bird of prey, especially with the Ultrablock filter in place. Visible to the naked eye as a fuzzy “star” in Orion’s sword; I even seem to remember it having a red colour when I was a kid, but I’m not sure how reliable this memory is.
XT10 at 50x: Very bright, greenish core almost overwhelming the Trapezium; detailed structure apparent with direct vision. Long “wings”, one sweeping out towards Iota Orionis. The Ultrablock filter significantly increases the extent of the nebula, particularly on the northern side. The Astronomik OIII filter gives a similar view to the Ultrablock, but with even more contrast between the nebula and the surrounding sky. The OIII also imparts a strong green colour, more so than any other object I’ve used it on.
92x: Exquisite detail in and around the Huygens region. Little arc of nebulosity visible in the opposite cavity wall, corresponding with the sculpted section seen in photos. Adding the OIII to the Ethos reinforces previous observations with this filter: it fills in the northern half of M42, giving the nebula a lopsided, asymmetric appearance.
133x: The extra magnification is better for picking out fine detail in the core of the nebula, but it doesn’t quite have the majesty of the Ethos view. Intricate detail seen with direct and averted vision, including nebulosity within the “fish-mouth” area. The dark lane between M42 and M43 contrasts nicely with the fainter nebulosity beyond the Huygens region, illustrating that the nebula is much more extensive than its initial bird-like appearance implies. Bright arc of nebulosity still visible on the opposite side of the cavity, but not quite as obvious as it was at 92x.
The southern wing of the nebula is remarkable: long and irregular but with well defined edges, like a ribbon of light. The adjacent part of the nebula appears distinct from the ribbon, but it’s more akin to a difference in texture than in colour, like silk and smoke.
As noted at the lower magnifications, the Ultrablock filter significantly fills out the northern half of the nebula. It also makes the Huygens region seem more boxy and sharper-edged, but otherwise there’s not that much improvement (that’s not a criticism of the filter; just that the core of M42 is bright enough not to need it.)
240x: Lots of intricate bright and dark structure visible even at this high magnification. The Trapezium stars seem to reside in a dark “hollow” within the Huygens region, but this may well be an illusory effect caused by my eyes constantly re-adjusting to the brightness of the stars.
The visibility of the 11th magnitude E and F stars in the Trapezium depends very much on the seeing. I’ve seen the E star in the SP-102 at 200x and in the XT10 at 92x without too much difficulty. On a good steady night the F star is also visible in the XT10 at 133x.
M43 (NGC 1982), emission nebula, Orion
133x. Comma-shaped haze surrounding a 7th magnitude star. Averted vision reveals a dark lane cutting into the nebulosity.
See also:
The whole region from Alnitak through to Iota Orionis is a visual feast for any telescope, but here's just a couple of highlights:
Sh2-279 (NGC 1973, 1975, 1977), Running Man Nebula, reflection nebula, Orion
133x: Gauzy appearance clearly more akin to the Merope nebula in the Pleiades than M42 to the south. Averted vision suggests a “bite” taken out of the southern edge.
NGC 1999, reflection nebula, Orion
133x. Peculiar little nebula south of M42 (and probably overlooked by a lot of observers for that reason) illuminated by 11th magnitude V380 Orionis. At first sight it appears as a small hazy halo with a star or star-like point at the centre. Its size increases with averted vision, and a dark hole becomes visible, adjacent to the “star”. Professional observations at infra-red and sub-millimetre wavelengths indicate that this really is a hole and not an obscuring patch of dust.
M44 (NGC 2632), Beehive Cluster (Praesepe), open cluster, Cancer
Just about visible to the naked eye with direct vision from my garden; becomes fairly easy with averted vision. Binoculars and the finderscope reveal about twenty stars in a familiar boxy pattern.
In the XT10, M44 is too large for the field even at 50x. At this and higher magnifications it looks more like a rich star-field than a cluster, but still makes for an attractive sight. Lots of bright stars arranged in twos and threes.
M45, Pleiades, open cluster, Taurus
The famous Seven Sisters, although only six stars are immediately obvious to the naked eye. With patience and some effort, it is possible to see more; the most I’ve been able to count is nine stars (plus a suspected tenth from the combined light of 21 and 22 Tauri), which probably represents the limit from my garden.
The best views of the Pleiades are in binoculars or a small telescope with a wide-field eyepiece, but the extra aperture of XT10 does at least reveal parts of the reflection nebula in this cluster.
50x: Cluster too large for the field even at this magnification, but NGC 1435 visible as a misty patch fanning out from Merope to the south, framed by dark “lanes” on either side. The nebulosity in the Pleiades is much easier to see when you know which stars aren’t involved in it, such as the distinctive line of stars trailing south from Alcyone. Additional nebulosity around Maia just about visible (NGC 1432).
92x: The reflection nebula is especially prominent in the Ethos – it almost looks like condensation has fogged up the optics. Nebulosity brightest around Merope, appearing large and fan-shaped, but not showing any of the banded structure apparent in photographs. Most of the bright stars in the Pleiades appear blue-white in colour, but one notable exception is the 8th magnitude double Burnham 536 in the centre of the cluster: the westernmost member of the pair has a reddish hue.
M46 (NGC 2437), open cluster, Puppis
92x. Rich cluster of moderately bright stars; a short hop east from M47. I really should have more to say about M46, but it contains a rather prominent distraction in the shape of NGC 2438, a planetary nebula which is immediately obvious as a grey disc of light on the northern edge of the cluster. Bright star on eastern edge of nebula, fainter one shining through.
NGC 2438 would arguably be one of the winter’s best planetary nebulae even if it didn't share a telescopic field with M46. Adding an OIII filter dims the surrounding starlight, thus making 2438 much more distinct, although it’s nowhere near as bright as NGC 2392 in Gemini. On first impression it looks a little like M57, appearing as a ring with a darker centre – although the dark core is smaller in size relative to the ring, giving the nebula a more donut-like appearance.
M47 (NGC 2422), open cluster, Puppis
92x. Rich mixture of bright and faint stars – very attractive in the Ethos. Brightest members form a triangle, with prominent doubles at east and west corners angled towards each other (the eastern pair of equal brightness), and another double star near the centre. This cluster is so prominent in the finder, I wondered if it might be visible to the naked eye from my garden; it is – with averted vision.
See also:
NGC 2423, open cluster, Puppis
92x: Moderately rich cluster north of M47, and somewhat overshadowed by the nearby brighter Messiers. Close double on western edge.
M48 (NGC 2548), open cluster, Hydra
92x: Rich, large, loose cluster of bright stars – a “typical” Messier cluster if there is such a thing. Curving line of stars to east, close double near centre.
133x: Less impressive at 133x than at 92x, although the higher magnification does reveal some fainter stars near the middle. Distinctive two-arm flattened “spiral” of stars winding out from the centre along a north-south axis.
M49 (NGC 4472), elliptical galaxy, Virgo
92x: Bright, round galaxy; quite bright towards the centre. 12th magnitude star east of the core.
M50 (NGC 2323), open cluster, Monoceros
92x: Rich, arrow-shaped cluster pointing west. Bright yellow-orange star on southern corner. On another occasion (using the same eyepiece) this star appeared somewhat redder.
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