Saturn at Opposition

3-4 August 2021, 23:30 – 01:30 (BST)

Having spent a good portion of the day walking round Stodmarsh Nature Reserve (for the first time in forever) in dazzling sunshine, my eyes weren’t really up for the challenge of observing faint objects, so I spent most of the session in the company of the two giant planets.

I caught Jupiter just as the GRS was disappearing around the limb. Unfortunately the neighbour’s tree seems to have put on a growth spurt, so I may not get an uninterrupted view of Jupiter this year after all.

Saturn was a couple of days past opposition, with the rings still glowing brightly, and I was even able to grab a half-decent image (below):

Titan and several moons were visible through the eyepiece, with Rhea, Dione and Tethys in a straight line just north of the planet.

I also had a quick look at NGC 7814 at 240x. Despite my eyes being nowhere near properly dark-adapted, I was still able to see Supernova 2021rhu. It was difficult to judge its brightness, but it seemed to have faded to somewhere around 13th magnitude.

Rhubarb Supernova

16-17 July 2021, 23:45 – 01:15 (BST)

Seeing: Average

Transparency: Average/poor

Conditions: After a run of cloudy nights, a very mild, cloudless evening with a light breeze blowing from the north. (And a near first-quarter moon sinking in the west.) I spent a lot of time carefully aligning and calibrating the astrophotography rig, only to find out later (for reasons I haven’t yet figured out) that it had stopped tracking after a few minutes, leaving me with over an hour’s worth of star trails. Oddly, it started tracking again (or attempted to, given that the autoguider had long since lost its target star) on the last few frames. I suspect a loose or snagged cable is the culprit, but I haven’t been able to replicate the fault in daylight. (This is the experience I expected to have when I first attempted this type of astrophotography back in 2018, not three years in. Oh well…)

While that was in progress (or not), I revisited some summer favourites with the XT10 at 133x: M57, M56, Albireo and M27. The dumbbell’s central star was visible again (with averted vision), but not as easily as it was at 171x.

Then, with my eyes sufficiently dark-adapted, it was onto some special extragalactic targets: 

BL Lacertae, Active Galactic Nucleus / Blazar

133x. Not the most visually exciting object (it looks like a faint, inconspicuous star in a field full of stars), but at approximately 900 million light years this is the second-farthest thing I’ve seen (after quasar 3C 273). I had to consult the MSA (chart 1123) to track it down, and even then I had to make a rough sketch of the field stars to be sure I had seen it.

BL Lac usually fluctuates between magnitudes 14 and 17, which would normally put it out of range of my scope, but it’s been exhibiting a lot of activity over the last few months and is now brighter than it’s ever been, currently pushing 13th magnitude.

SN 2021rhu, Supernova in galaxy NGC 7814, Pegasus

At long last, a supernova bright enough for my scope, and in a place where I could see it. That said, I had to wait for Pegasus to clear the neighbour’s fence before I could get the XT10 on it, but even though it was still low in the sky, the supernova was immediately obvious at both 133x and 171x, shining relatively brightly against the faint haze of NGC 7814 at approximately magnitude 12.5. It appeared as an intense star-like point slightly east of the galaxy’s centre (I wasn’t able to see the galaxy’s dark lane). Quite an impressive sight considering it’s 40 million light years away (but bad news for anyone unfortunate enough to be within a few light-years of the explosion).

Apparently SN 2021rhu (with that name I can’t help but think of it as the “rhubarb supernova”) is a type 1a supernova. This is caused by a white dwarf accreting matter from a nearby companion star until electron degeneracy pressure can no longer support its mass – resulting in a rapid collapse, a runaway nuclear reaction and a spectacular explosion that rips apart the entire star.

Also: I was treated to three very bright passes of the ISS over the course of the evening. One pass was so bright I could see a halo around it.

---

I went out again the following night (17 July – 18 July) for another attempted imaging run which resulted in 8 minutes of perfect data followed by another hour or so of trailed images. [Insert expletives here.]

Fortunately I was able to salvage something from the session by sticking the camera on the XT10 and grabbing some data on Jupiter while a Ganymede shadow transit was in progress (below).

Detail-wise, there wasn’t much to choose between the image and the eyepiece view (at 240x): the brown barges above the NEB showed up well, but I didn’t spot the string of white ovals in the southern hemisphere (which are just about visible in the full-size image).

I also had a look at Saturn as it emerged from behind the neighbour’s tree. Several moons were visible and lots of fine detail was briefly visible in the planet and the rings, although the seeing quickly deteriorated.

I also had another look at SN 2021rhu (at 240x). The supernova was still quite prominent despite my eyes not being properly dark-adapted. It’ll be interesting to see if it’s still visible in August once the moon has got out of the way.

Nature note

The mosquitoes were out in force on both nights; in all the years I’ve been doing astronomy I’ve never been bitten quite like that before.

Clusters in Cygnus and Scutum

7-8 July 2021, 23:30 – 02:00 (BST)

Seeing: Average

Transparency: Average/poor

Conditions: A breezy night with patches of high cirrus passing overhead; quite cool for the time of year. England won a major football semi-final tonight for the first time in 50+ years, so there was lots of noise coming from the town centre: people singing and car horns blaring until well after 1 AM.

Light condensation building gradually over the course of the session – mostly on the atlas and the telescope tube; fortunately the optics remained unaffected up until the last few minutes.

NGC 7044, open cluster, Cygnus

133x. I’ve looked at a lot of Cygnus clusters recently, and most of them have been immediately obvious. However, at first all I could see here were two moderately bright stars embedded in a very small and very hazy knot of light. Averted vision showed another faint haze nearby, but it was unclear whether one or both of these belonged to the cluster. At 171x a few stars popped out with averted vision, and a third star joined the two brighter ones to form a triangle. Perhaps not the best object to start a session (I was expecting something brighter).

NGC 7027, planetary nebula, Cygnus

171x. Small but bright blue-green nebula with bi-lobed structure. Bright spot stood out on the western side – as noted on previous occasions.

NGC 7086, open cluster, Cygnus

133x. Rich, compact cluster (visible as a hazy patch in the finder). Stars arranged in a loose, ragged spiral. Orange star on the western side. Underlying haze of unresolved stars.

NGC 7063, open cluster, Cygnus

133x. Large, loose cluster of bright stars with a central asterism shaped a bit like a stick representation of a horse.

I then relocated to the constellation of Scutum and, after spending some time in the company of M11 (the Wild Duck Cluster), I revisited an open cluster and a globular cluster:

NGC 6664, open cluster, Scutum

133x. Large, loose and sparse collection of moderately bright stars, shaped a bit like a partially peeled banana. Slightly washed out by the glare from 4th magnitude Alpha Scuti to the west.

NGC 6712, globular cluster, Scutum

133x and 171x. Grainy round glow in a rich star field – seemed larger than I remember. Bright field star to east. Faint stars visible with averted vision; even more so at 171x, though the field is so rich it’s hard to tell which ones belong to the cluster and which belong to the Milky Way. The cluster itself appeared “lumpy” at this power, with a prominent knot of stars south of the core. I’ve been underwhelmed by this object in the past, but tonight it really came to life – the best view I’ve had to date.

I spent quite a lot of time looking at this cluster, and at one point a slow-moving MEO satellite crossed the field on a southerly trajectory, its brightness oscillating slightly as it rotated.

NGC 6934 (Caldwell 47), globular cluster, Delphinus

171x. Small, compact globular; more condensed than 6712, with a brighter core. Bright 9.5m star leading 2’ to the west. Grainy with averted vision, but harder to resolve than 6712. The most prominent members appeared to be south of the core, with another one just northeast of the core.

M27 (Dumbbell Nebula), planetary nebula, Vulpecula

171x (no filter). Large and boxy at this power; no obvious colour. Brightest field star on the western corner, with a couple more visible through the northern half of the nebula. The central illuminating star wasn’t immediately obvious against the nebulous background, but was visible with averted vision, popping in and out of view with the seeing. It's not particularly difficult, but you have to make a conscious effort to seek it out, which is probably why I haven’t seen it before. Sources seem to vary on the brightness of this star: some have it at 13th magnitude; others have it nearer 14th magnitude. Based on my observation, I would put it nearer 13 than 14.

I rounded off the session with a first look at Jupiter for the year, starting at 171x, before moving up to 240x and then 333x. (Saturn is still low and currently behind the neighbour’s fast-growing tree for most of the night, but Jupiter looks like it might just clear it.) All four Galilean moons were on view (one west, three east) and the Great Red Spot was on the meridian, looking a bit faded compared to the last time I saw it. By contrast the NEB had a very dark core and a distinct orange-brown hue. I was almost tempted to get the laptop and capture some videos, but the condensation started to interfere at this point. Bodes well for the next couple of months though.