Exploring Delphinus

1 September 2019, 21:30 – 01:00 BST

A cold night, and too breezy for imaging. Instead, for a change, I put the TV60 to use as an observing scope while the XT10 cooled to ambient temperature.

Transparency: not as good as 30 August
Seeing: Good to begin with, but worsened as the night progressed.

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TV60 + 24mm Panoptic (15x)
It’s a treat to just ramble along the Milky Way at this magnification, but the most noteworthy observations came when I added the OIII filter:

Veil Nebula, supernova remnant, Cygnus
Both arcs were visible (albeit faintly) in the same field of view. (This wasn't a surprise to me as I'd already tried this some years ago using the Ultrablock filter, although my notes from that time state that the western segment 6960 was only just on the threshold of visibility.) I think from a really dark site, Pickering’s/Fleming's Triangle might even be possible with this combination. Something to bear in mind perhaps the next time I take the TV60 on holiday.

NGC 7000, North America Nebula, Cygnus
Large and prominent at this magnification, and the OIII filter confirmed it as clearly nebulous in nature and not just a star-rich section of the Milky Way. The brightest section was the part adjoining the “Gulf of Mexico.” (Again, this replicated an observation made some years previously using the Ultrablock filter.)

NGC 281, Pac-man Nebula, Cassiopeia
Showed up well as an amorphous little glow, albeit devoid of detail.

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Other observations for the night were carried out with the XT10, using (unless otherwise stated) the 9mm Nagler (133x).

NGC 6716, open cluster, Sagittarius
Tight, boxy little cluster, shaped a bit like a backwards “2”.

Cr 394, open cluster, Sagittarius
Sprawling cluster, larger than 6716.

NGC 6818, Little Gem Nebula, Sagittarius
Tough to find (in a bright part of the sky with no naked eye stars nearby), but when I did track it down, it presented as a bright little disc, becoming even brighter with the Ultrablock filter (the OIII was still on the TV60). Prolonged examination revealed a dark core – a typical summer planetary. I also looked for the nearby Barnard’s Galaxy, but (as expected) it was hopelessly lost in the light pollution.

M75, globular cluster, Sagittarius
Grainy little fuzzball, washed out by light pollution. No stars resolved. Seemed quite small compared to other globulars, but perhaps I was only seeing the core region.

NGC 6934, globular cluster, Delphinus
Another grainy, unresolved glow. Appeared to have a slight bluish tinge. Bright field star to west.

Gamma Delphinus, double star
Impressively bright and close double star with an equally close (but fainter) pair of stars to the north. Reminiscent of Epsilon Lyrae.

NGC 7006, globular cluster, Delphinus
Faint round glow, brighter towards centre, but lacking the grainy appearance of the previous two globulars viewed tonight. Looked more like a comet than a globular cluster.

M72, globular cluster, Aquarius
Weak round glow, very faint for a Messier globular.

NGC 6891, planetary nebula, Delphinus
Very small disc of light, almost stellar (which explains why I overlooked it on 25 August). Needed the Nagler 5mm (240x) plus the Ultrablock to confirm its nature. Seemed slightly elongated at high magnification.

Couldn’t find NGC 6886 (I’m guessing it’s even tinier than 6891), but NGC 6905 (the Blue Flash Nebula) showed up well at 240x. Smoke ring of asymmetric brightness sitting in a triangle of stars.

NGC 185, galaxy, Cassiopeia
An exercise in frustration (the sky conditions didn’t really justify the amount of time I spent on this and 147), but eventually I located NGC 185 (one of M31’s outlying satellite galaxies). Soft round glow – very faint and featureless. No sign at all of NGC 147. Not a night for faint galaxies.

NGC 7293, Helix Nebula, Aquarius
A little more washed out by light pollution / poor transparency compared to Friday, but still impressive. With the Ultrablock I could make out several field stars surrounding the helix.

The Helix Nebula and other Highlights

30 August 2019, 22:30 – 01:00 BST

Much better transparency tonight – ideal for photographing my primary target for the autumn: M33. And the previous sessions had given me enough confidence in the imaging and autoguiding rig to leave it alone while it captured two hours’ worth of data. (With no bright stars nearby, the hardest part was getting the galaxy centred in the camera’s field of view.)

After idly touring the Milky Way while my eyes fully adapted to the dark, it seemed only right that I open the session with a closer look at the object I was imaging:

M33, Triangulum Galaxy
Viewed at both 50x and 133x; challenging as always. The northern spiral arm was easier to see than the southern one. The nucleus was star-like, with a faint star close to it (in line with NGC 604). Some of the other HII regions were suspected with averted vision, but not to the point where I could say I was confident of detecting them. I used a finder chart to pinpoint the location of the globular cluster C39 but, not surprisingly, it was below the threshold of visibility.

NGC 7331, spiral galaxy, Pegasus
Viewed at 133x and 240x. At the higher magnification there was perhaps a hint of one of the companion galaxies, but it was extremely subtle. Likewise, there was a very vague suggestion of a misty glow in the region where Stephan’s Quintet is supposed to be, but not convincing enough for me to call it.

NGC 7009, Saturn Nebula, Aquarius
Bright ellipse at 133x. At 240x with the OIII filter it became very bright, albeit devoid of detail. I couldn’t see the ansae directly, but with averted vision I could tell there was something “Saturn-like” about its shape. The nickname is well-deserved; at first glance it does look a lot like a ghost image of the ringed planet.

M2, globular cluster, Aquarius
Best view yet of this globular. Large, slightly elongated, well resolved, particularly with averted vision. The brightest member is just to the east-northeast of the core (though this may be a foreground star).

M15, globular cluster, Pegasus
Viewing one globular straight after another really allows you to appreciate the differences. M15 is brighter than M2 and clearly more condensed. Easier to resolve too (more stars visible in direct vision).

NGC 7293, Helix Nebula, Aquarius
With a declination of -21 degrees and a reputation for having a low surface brightness, I wasn’t sure if I was going to be able to see this planetary nebula, but a sweep of the area at 133x with the OIII filter quickly brought it into view. It showed up surprisingly well, looking not unlike its familiar photographic representation (albeit minus the colour). Even though I’d read about it before, I was still unprepared for just how big it appeared in the field of view. Overall it resembled a pair of large, ghostly overlapping smoke rings, with a darker cavity on the northwest edge and a hollowed-out interior. At 50x (still with the OIII filter) it was brighter still. The only other planetary nebula I can think of that vaguely resembles it is the Owl Nebula in Ursa Major, but the Helix is superior in every way (not just size). Easily the highlight of the evening. Afterwards, I removed the OIII filter to test if I could see it unaided, but it had left the field of view by the time I put the Panoptic back in and I couldn’t find it again. I’m pretty certain I was sweeping in the right area, so file that as another success for the OIII filter.

Nature note:
At least 10 frogs in the pond, including several of this year’s froglets and the large pale “telescope-hopper” from Monday night.

A Bow-tie in Cepheus

27 August 2019, 22:00 – 23:00 BST

The third clear night in a row, although the transparency was rather poor. The imaging target for the evening was the globular cluster M15.

Observations of M15, M71, M57 and NGC 7662 were affected by the conditions and so not really worthy of note-taking, although the latter (7662) did show a hint of a darker core at the higher magnification of 240x. However there were a couple of other highlights:

M103, open cluster, Cassiopeia
Triangular cluster with prominent red star at centre. While sweeping the scope towards Epsilon Cas I stumbled upon a tiny little cluster of stars, the four brightest stars of which formed an almost dead straight line. Not plotted in PSA, but confirmed in Uranometria as Trumpler 1.

NGC 40, The Bow-tie Nebula, Cepheus
Medium sized planetary nebula; faint envelope surrounding central star (not unlike the Crystal Ball Nebula in Taurus). The addition of the OIII filter gave a hint of a lobed structure, at the expense of the central star (which was swamped by the nebulosity). Worth revisiting under better sky conditions.

Other notes
Saw another late Perseid streaking through Lyra towards the end of the evening.