Summer Clusters and Nebulae

14 -15 July 2018, 23:00 – 02:00 BST

A very clear night, if not completely dark; good enough to see 5th magnitude stars after dark-eye adaption, and the Scutum star-cloud with averted vision (although the latter seems to be more affected by light pollution than ever).

Saturn looked very impressive when I first pointed the telescope at it, with the usual moons in attendance and the Cassini Division visible most of the way around, but the seeing deteriorated rapidly as it passed the meridian. (Possibly due to warm air rising off the pond and the surrounding concrete.)

M39, open cluster in Cygnus
A sparse cluster of bright stars, spilling outside the edge of field of view even at 50x. Too loose and large for a big reflector; I wasn’t even sure I was looking at a cluster at first.

NGC 7062, open cluster in Cygnus
A grainy, fuzzy patch of nebulosity at 50x; starts to resolve at 133x. Faint stars.

NGC 6910, open cluster in Cygnus
A grouping of bright stars arranged in a kind of flattened Y-shape. Not rich, but well-framed at 50x. Quite pretty; would probably have greater appeal if it didn’t already reside in such a rich section of the Milky Way.

M29, open cluster in Cygnus
Boxy, like a mini version of the Pleiades. The extra aperture doesn't really add anything to this cluster that I hadn't already seen through the 4-inch.

NGC 7000, North America Nebula in Cygnus
Scanned region with Ultrablock, but too large for fov. Could tell that some areas were brighter than others but hard to distinguish nebulosity from the sheer number of background stars.

NGC 6888, Crescent Nebula in Cygnus
I spent a lot of time looking for this with the 4-inch and never convinced myself of seeing it, but I found it right away with the XT10 (Panoptic 24 mm + Ultrablock). Appeared as an elongated semi-circle of stars connected by bright streaks of nebulosity. Closer examination showed a faint haze filling the interior of the crescent, giving the impression of a baby wrapped in swaddling clothes, with a darker region where the face would be.

I left the Pan 24 and the Ultrablock in place and moved down to 52 Cygni and the Veil Nebula, supernova remnant in Cygnus: now high overhead and even more vivid than the previous sighting. The Witch’s Broom still looked like a frozen funnel cloud, a twisted spike of nebulosity extending beyond 2 fovs. The Eastern Veil showed more detail; both halves are very clearly “structured” nebulae, in that they have clearly defined edges as opposed to the more typical cloudy nebulae which just fade gently into the background sky.

M57, Ring Nebula in Lyra
Studied at 240x, with and without the Ultrablock filter. Holds its brightness well at high magnification in the XT10. Otherwise as per previous description. Slight green-grey colour.

M27, Dumbbell Nebula in Vulpecula
The "apple-core" took on a more boxy appearance at 240x. Distinct, sharp cut-off in brightness on one edge, and strong hints of structure within the nebula – most prominent being the diagonal bar commonly seen in photos like the one above.

M11, Wild Duck Cluster in Scutum
Not much I can add to the previous report. Just a fantastic cluster to look at in the XT10.

NGC 6712, globular cluster in Scutum
Stumbled upon this while sweeping south of M11. Fuzzy, circular blur at 50x, but starts to betray its true nature at higher magnification. Reminded me of M13 as seen in the smaller scope.

M15, globular cluster in Pegasus
Well resolved, very condensed core – more so than other globulars I’ve looked at. Definitely worth revisiting when it's higher in the sky. Nearby field stars really help frame this object at both 50x and 133x, giving it a 3D appearance.

NGC 7006, globular cluster in Delphinus
Small, circular blur. Relatively easy to see in the XT10, but no stars resolved.

NGC 7331, spiral galaxy in Pegasus
This galaxy displays a bright core nestled in a fainter disc, very much a mini M31. Suggestion of asymmetry on one side. Couldn’t see the companion galaxies (the “tadpoles”) on this occasion, but I think they should be visible on a darker night with higher magnification. (Ditto for Stephan’s Quintet.)

NGC 7662 (Blue Snowball), PN in Andromeda
I find it hard to distinguish between blue and green in low light, but this definitely has a bluish turquoise hue compared to, say, the grey-green of M57. Appeared circular at 133x, with a hint of a darker core.

Almach (Gamma Andromedae), double star
Lovely pairing of a pale yellow primary and a sky-blue secondary. (Looking back at the notes I made with the 4-inch, I've previously described the colours as straw and aquamarine.)

Tiredness was really starting to creep in at this point (and dew was forming), so subsequent observations fall into the “just one more object” category.

M52, open cluster in Cassiopeia
Rich cluster, worth revisiting in the autumn.

M31, Andromeda Galaxy
Showing a frustrating lack of detail despite its brightness. Obviously, higher altitude and darker skies should improve things, but perhaps higher magnification might increase the contrast at the expense of the “big picture”.

M33, Triangulum Galaxy
Large circular blur devoid of any real detail, but at least it was obvious (unlike in the 4-inch) despite being fairly low in the sky. Averted vision showed a distinct, almost star-like condensation at the nucleus – not something I recall seeing before.

Finished off with a first look at Mars through the XT10. As big as I’ve ever seen it (and ever likely to see it), but rendered featureless by the global dust-storm. Hint of a brightening at the poles, but low altitude causing a lot of colour dispersion. Even to the naked eye it looks pale yellow rather than its usual amber hue.

The Wild Ducks of Scutum

4 -5 July 2018, 23:30 – 01:00 BST

Another look at Saturn but (as on previous nights leading up to this), the seeing wasn’t good enough to justify setting up an imaging run. The moons were easier to see at 133x.

Epsilon Lyrae resolved much easier than the previous session - though this time, due to the seeing, the clearest separation came at 133x.

A quick first look at the Double Cluster and the Andromeda Galaxy, rising out of the northeast. The former looked spectacular at 50x, despite some obstruction from intervening foliage.

The Andromeda Galaxy (M31) showed a very bright core with a condensed, stellar nucleus. Too big for fov even at 50x. Lots of field stars superimposed over the galaxy; dark cut-off from dust lane clearly seen; M31 and M110 also showed up well. Outer environs of M31 not well seen due to sky brightness; dust lane aside, it was very hard to tell where the galaxy ended and space began, so to speak.

NGC 7000, North America Nebula in Cygnus
Scanned this region at 50x. Couldn’t be sure of seeing the nebula, but the richness of stars in this region was remarkable. Will revisit on a darker night.

M11 (the Wild Duck Cluster) in Scutum
The undoubted highlight of the night. Extremely rich, compact fan-shaped cluster at 50x. Switching to 133x showed the stars arranged in roughly half a dozen clumps separated by dark lanes – giving it a “fractured” appearance. Prominent 8th magnitude star at apex of fan; lots more stars revealed with averted vision. Better than any photo – has to be seen to be believed.

Observing in the Astronomical Twilight

25 June 2018, 23:30 – 01:00 BST

Deep-sky observing (of faint objects at least) is limited in the few weeks either side of the summer solstice, but fortunately the moon and the planets were on show. After a week of observing (and imaging) Jupiter (and properly seeing the moon’s Hadley Rille for the first time despite less than ideal seeing conditions), Saturn finally took centre-stage. While waiting for it to emerge from behind the neighbour’s tree, I looked at the following:


Epsilon Lyrae (The Double Double)
At 133x the stars showed obvious elongations, but no clear split. At 240x both pairs were resolved, but the stars had a spiky appearance, sometimes interfering with each other’s diffraction patterns.

Mu Cephei (The Garnet Star)
I wouldn’t go so far to describe it as red, but it definitely had a rich orange hue. Would be interesting to gauge the effects of different magnifications and seeing conditions on the perceived colour.

Saturn
The rings were wide-open and bright (with opposition only a few days away). Despite the low altitude (it barely cleared the fence) and variable seeing (a feature of the evening), this was by far the best view I’ve ever had of Saturn. The Cassini Division was easily resolved almost all the way around; the inner B ring was clearly brighter than the outer A ring. Saturn’s globe was well defined against the rings, giving it a 3D appearance; the usual darker equatorial cloud belt was also visible. Multiple moons seen despite the glare from the rings; according to the Sky & Telescope online app I saw Dione, Tethys, Rhea, Titan and (fleetingly) Enceladus.

Nature Note:
Another reason to tread carefully while moving the telescope from inside to outside (and vice versa): I’ve shared my recent observing sessions with dozens of tiny froglets which emerge from the pond every evening after dark.

First night out with the new scope

18 – 19 May 2018, 22:30 – 02:00 BST

The sky was a little hazy and never completely dark, so for the most part I stuck to the bright showpiece objects. Best views came with the 9 mm Nagler – darker sky, better contrast. The scope took a good hour to cool down, but when it did the views were spectacular.

M13, great globular cluster in Hercules
In a word: wow! After switching from the 24 mm Panoptic to the 9 mm Nagler, pinpoint stars were resolved (in direct and averted vision) right across the face of the cluster, giving an impressive sense of scale and distance. After a while I could perceive chains of stars curving out from the centre. The first night was supposed to be a whistle-stop tour of some old favourites but I couldn’t tear myself away from this object. The longer I looked, the better the view got. I've viewed M13 many times with the 4-inch scope but now for the first time I could see it as a proper cluster of stars and not just a grainy snowball hovering on the threshold of resolution. (The photo above really doesn't do the spectacle justice.) At one point a satellite (space junk?) glided right across the middle of the cluster, followed a minute or two later by a second object travelling on the same path.

M57, Ring Nebula in Lyra
Very bright outer "donut", gauzy central region, brighter edge on one of the long sides. Faint star clearly seen adjacent to nebula.

M5, globular cluster in Serpens
Easier to find than I thought it would be. Smaller, more condensed than M13, but the XT10 resolved it well despite it being in a brighter part of the sky. Relatively bright star just off centre. It seemed (and I’ve thought this before with the Vixen SP-102) that although M13 is bigger and brighter overall, the brightest stars in M5 are brighter than the brightest ones in M13.

M81 and M82, pair of galaxies in Ursa Major
Not well-placed for observing now, but I couldn't resist looking at the Great Bear's famous galaxy pair. M81 showed a bright condensed core and not much else (I’ve no doubt the outer structure will be more evident on a better night). M82 was a surprisingly long streak of light (making me look forward to the likes of NGC 891, etc.) and the bisecting dark lane was clearly visible.

Despite its low altitude this year, Jupiter in the XT10 was as good as I’ve ever seen it. It was dazzlingly bright with the 9 mm Nagler, but the best view came with the 5 mm Nagler. Alt-Az tracking wasn’t any problem either, although it helped that it was near the meridian. Fleeting moments of good seeing revealed plenty of fine detail in and around the belts, with a noticeable “kink” in the NEB. The GRS was immediately obvious and – once my eye had adjusted to the brightness – its brick red hue stood out. All four Galilean moons were visible, but with no obvious signs of colour or resolution.

Veil Nebula, supernova remnant in Cygnus
I switched back to the 24 mm Panoptic for this one. As I anticipated, the sky wasn’t dark enough to see it with direct vision, but when I added the Ultrablock filter it immediately popped out. The Witch’s Broom (running through 52 Cyg) looked like a funnel cloud frozen in space, tapering to a sharp point. I had to sweep to find the other section, but again it popped out from the dark background, showing the distinct “chicken-bone” shape familiar from photographs, and a suggestion of a braided structure.

M27, Dumbbell Nebula in Vulpecula
Very bright with or without the Ultrablock. Appeared sharper on one side and ever so slightly bluer than M57. I need to spend more time on this object, but it's already clear that the XT10 is going to be an excellent scope for high-magnification viewing of planetary nebulae.

M71, globular cluster in Sagitta
Quick look, partly resolved. Loose for a globular.

NGC 6939, open cluster in Cepheus
Partially resolved, triangular shape. Appearance much the same as the photo I took recently.

Albireo, double star in Cygnus
One of the northern sky's showpiece doubles. Improved as it gained altitude; looked better at 50x, but perhaps the brightness was overwhelming the colours a little.

M51 and NGC 5195, Whirlpool Galaxy and companion in Canes Venatici
Again, not well placed, but both galaxies showed bright cores. A hint of spiral arm structure in M51, with a star superimposed over the face of the galaxy (definitely not a supernova).

Other impressions: lots of satellites/space junk seen passing through the field of view, often in pairs (According to Stellarium the brighter ones were from the GlobalStar family). The night included a very bright ISS passage - almost overhead - and visible most of the way down to the horizon.

Introduction

In April 2018, I made my first serious foray into astrophotography, as discussed here on telekilnesis, using a Tele Vue 60 refractor mounted on a Vixen Super Polaris equatorial mount. Of course, once an imaging session is up and running there's little for the astrophotographer to do other than wait for it to finish. Some choose to go back indoors and have a drink or watch TV, but I'm a visual observer at heart and it seemed like a missed opportunity.

My 102mm achromatic refractor (which used to sit on the Super Polaris) no longer had a mount, and I felt like I'd pushed the limits of what I could see through that scope (plus my eyes aren't getting any younger), so the inevitable craving began for a new, larger telescope.

The first part of the search wasn't difficult: if all you want is the pure observing experience (and you don't need a GOTO mount to navigate the night sky) then a basic Dobsonian design represents the biggest aperture for the least expenditure.

The second part took a little longer, but I eventually settled on the Orion SkyQuest XT10 Plus (other makes and models are available). A 10-inch reflector is probably the biggest scope I can safely carry out to the garden and back, and the eyepiece is almost always at a comfortable height for viewing while sitting down. (Equatorial mounts are great in so many ways, but I can't tell you what a relief it is not to have to contort my back anymore to look at objects near the zenith.)

So why keep a log?

Like other visual hobbies such as birdwatching or painting, telescopic astronomy rewards prolonged observation and careful study. If you look at a faint nebula or galaxy only once, you haven't really seen it. It takes time and techniques such as averted vision, scope-tapping and enhanced breathing to tease out the subtle details. And in most cases, it's not until you go back to it a second or third time that you really get a full appreciation for what you're looking at. But with so many objects to observe, if you haven't kept notes then how can you remember what you saw last time? For example, what was the optimum magnification for viewing a particular planetary nebula? Was it symmetrical? Was any colour apparent? Was it brighter on one or more sides? Was the central star visible? And so on...

I've tidied and expanded my notes to make them more presentable, but they were written largely for my own benefit and will probably read as such. But if you're curious to know what the universe looks like through a 10-inch reflector, or if you just want to compare my observations with your own notes, then you might find something useful here.

A final caveat: just so this blog isn't completely text-heavy, I will include some of the images I've taken with the TV-60. These aren't meant to represent the view through the eyepiece - no amateur telescope will show you the colour and detail in a long-exposure image. But then again, no photo will ever capture the immersive experience of gazing at a rich cluster of pinpoint stars through a wide-field eyepiece...

Equipment Summary

Orion XT10 with a Tele Vue 9 mm Nagler

Telescopes / Binoculars

Orion SkyQuest XT10 PLUS 254 mm f/4.7 Dobsonian Reflector (an enhanced version of the classic XT10 which comes with a dual-speed Crayford focuser and altitude tension adjustment, among other things)

Tele Vue-60 APO Refractor (which, when it isn't being used for photography, provides stunning widefield views of the night sky)

Swift 781 Aerolite 7x50 Binoculars

Eyepieces

Tele Vue 24 mm Panoptic (50x)
Tele Vue 9 mm Nagler (133x)
Tele Vue 5 mm Nagler (240x)

28 mm Deepview (43x)
10 mm Sirius Plossl (120x)
(The latter two eyepieces came with the XT10. They're perfectly fine as starter eyepieces go, but when you already own a set of Tele Vues, well...)

Barlows / Powermates

Tele Vue 2.5x Powermate
Orion 2x Shorty Barlow

Filters

Orion UltraBlock Narrowband 1.25"

Atlases

Each atlas has its own strengths and weaknesses, but if I had to recommend one it would undoubtedly be Sky & Telescope's Pocket Sky Atlas. This smartly-designed book divides the night sky into 80 charts mapping the stars down to magnitude 7.6, plus (in the jumbo edition) a further ten close-up charts depicting regions of interest such as Orion's belt and sword, and the Virgo galaxy cluster.

Observing Location

On a good night the limiting magnitude (NELM) from my back garden is about 5.5, which is equivalent to 6 on the Bortle Scale (Bright Suburban Sky). I find the best views are from the zenith towards the west and northwest (the shortest distance between me and the sea - and thus containing the least amount of light pollution).