Nova RS Ophiuchi

10 August 2021, 21:30 – 22:00 (BST)

Conditions: Warm, breezy. Hazy bands of cloud moving across the sky from the southwest.

2021 is turning into quite the year for novae, with news breaking on 8-9 August that recurrent nova RS Ophiuchi had flared up after a 15-year lull. Despite the sky not being completely dark and some interference from hazy cloud, the nova was easily visible in 7x50 binoculars, forming a triangle with Nu and Mu Ophiuchi. (It doesn’t appear in the PSA, but it is plotted on chart 15 of SA 2000 as N1967.)

The variable haze made it hard to estimate its brightness, but after comparing it with other stars in the field of view, I’d guess it was somewhere between magnitude 5.5 and 5.0 (perhaps a little closer to the brighter end of that scale). When not in outburst it normally lurks at somewhere around 12th magnitude.

This is the third bright nova of the year and – even more remarkably – all of them have been easily visible from the northern hemisphere at convenient times of the evening. See more at:

https://skyandtelescope.org/astronomy-news/recurrent-nova-rs-ophiuchi-just-blew-its-top/

Also: While I was looking at the nova, two satellites and a faint Perseid meteor passed through the field of view.

Goodbye Nova Herculis 2021

13-14 June 2021, 23:40 – 00:50 (BST)

Seeing: Average

Transparency: Poor

Conditions: A mild night with a light breeze. Very slight layer of condensation on the telescope tube after an hour.

All of tonight’s observations were carried out at 92x with the 13mm Ethos.

Nova Herculis 2021 (aka V1674 Her)

I was eager to see if the nova had got any brighter in the last 24 hours, but instead I found it had faded considerably by a good two magnitudes. (It was at a similar brightness to the nearby 8.5m field star HD 175919.) I didn’t notice any colour to the nova last night, but tonight it had a slight orange hue. I’ll be interested to read the explanation for this rapidly evolving nova’s behaviour once the analysis is completed, but in the meantime see:

https://skyandtelescope.org/astronomy-news/bright-nova-hercules/

Obviously, I’m glad I made the effort to see this nova last night rather than leave it for a day. It’s quite something to see a star change its appearance so dramatically in such a short span of time.

As well as V1674 Her, I also revisited a few other targets from last night. As expected, 61 Cygni looked lovely in the Ethos: a pair of pale orange headlights suspended in a sea of stars.

Open clusters NGC 6755 and NGC 6756 just about fit in the same fov at 92x, but I need a darker sky to really do them justice at this magnification.

But NGC 6709 did look better tonight. The Ethos gave the cluster more room to “breathe” and the v-shape formed by the brightest stars was more prominent.

NGC 6738, open cluster, Aquila

Plotted in SA 2000. Large, sparse cluster with a meandering line of stars running through the centre. Not impressive; I can see why it was left out of the PSA. Some sources don’t even recognise it as a real cluster.

NGC 6940, open cluster, Vulpecula

A long overdue return visit to this underrated cluster (its status isn’t helped by its proximity to the Veil Nebula.) Large, rich cluster of uniformly bright stars – fits nicely in the Ethos fov. A prominent red star (VG (or FG?) Vulpeculae) near the centre and a bright, close double on the western side of the cluster.

NGC 6826, “Blinking Planetary”, Cygnus

In same field as 16 Cygni in the Ethos; it’s hard to stop your eye constantly flicking from one to the other. Pale blue-green disc with a bright central star.

I rounded off the session with a look at the famous black hole Cygnus X-1, or to be more precise, its visible-light companion HDE 226868. It’s not that hard to find if you’ve got a decent map (I used chart 119 from my old copy of Uranometria). It’s the southernmost of a pair of 9th magnitude stars in a rich star-field near Eta Cygni. Like Nova Herculis 2021, this is a view to savour while you contemplate its astrophysical significance. I may not be able to see the black hole, but more I stared at that little patch of sky, the more I felt like it was staring into me.

Also, I wasn’t aware of this at the time, but Cygnus X-1 is right next to the much-photographed Tulip Nebula (Sh2-101).

Hello Nova Herculis 2021

12-13 June 2021, 23:50 – 01:50 (BST)

Seeing: Poor

Transparency: Average / poor

Conditions: A breezy night with the occasional small patchy cloud passing by. Noticeably chillier than Thursday night. Also, some light condensation.

Nova Herculis 2021 (aka V1674 Her)

You wait ages for a nova to come along … and now another one appears, perfectly placed for summer viewing on the Hercules / Aquila border. I had the MSA (Millennium Star Atlas) bookmarked ready for this one (Volume III, chart 1222), but it turned out I didn’t need a detailed chart; the nova jumped straight out in the finder, blazing away at somewhere between magnitude 6.0 and 6.5. Through the eyepiece at 133x it appeared as an intense little point of light, dominating the surrounding star-field. Although there wasn’t much more to see, I spent a long time in the nova’s company. It’s fascinating (and a rare treat) to look at such an object and imagine the thermonuclear processes involved as a white dwarf leaches material from a companion star, culminating in an explosive eruption.

While in the area I also noticed an interesting grouping of four stars to the west: two 8th magnitude stars flanked by two fainter stars, all in a roughly east-west straight line.

NGC 6709, open cluster, Aquila

133x. Pretty cluster of moderately bright stars arranged in a rough zig-zag pattern. Fairly large and loose; as noted last year, the centre appeared somewhat empty of stars. Visible in the finder as a misty patch of light.

At around 1:10 I noticed a really bright flare from a satellite passing overhead (travelling south to north).

NGC 6755, open cluster, Aquila

133x and 171x. Faint spray of stars in a rough crescent shape, with a stream of fainter stars tailing off to the east. Brightest member on the western end of the cluster.

NGC 6756, open cluster, Aquila

Located about half a degree NNE of 6755 (plotted in the PSA but not SA 2000). 133x: An even fainter fuzzy patch, and also somewhat smaller than its neighbouring cluster. Faint stars popping out with averted vision. At 171x I could see a tight, elongated core of faint stars, surrounded by a broken almond-shape of brighter stars, like an eye. I imagine this cluster would look quite good under a properly dark sky.

Beta Lyrae, Lyra

133x. Bright white star with three companions forming a triangle around the primary.

Delta Cygni, double star, Cygnus

171x. Brilliant icy blue-white primary with a very close companion 2.4” to the south. (I’m glad I used the DeLite for this one.) Beautiful split between the two stars when the seeing allowed.

61 Cygni, double star, Cygnus

171x. Lovely pair of bright yellow-orange stars in a rich star-field (must revisit this one with the Ethos). The separation appears similar to Albireo, and (like Albireo) the split was just about visible in the 9x50 finder. Like Barnard’s Star, this pair is a relatively close neighbour to the sun at 11.4 light years.

As I’d started the session with a nova, it seemed appropriate to finish with one: a return visit to Nova Cassiopeia 2021, which appears to be holding steady at somewhere between 7th and 8th magnitude.

Galaxies in Serpens Caput (and a Nova in Cassiopeia)

13-14 May 2021, 23:30 – 00:30 (BST)

Seeing: Average / Good

Transparency: Average

An unexpectedly clear night (for an hour at least), defying every forecast I’d looked at. Cool air, no wind (at ground level), light condensation on the telescope tube after a few minutes, but fortunately the lenses and mirrors stayed clear. Clouds low in the south, moving slowly north.

Anticipating that my observing time would be limited I stuck with just one eyepiece for the session: the 13mm Ethos at 92x.

M5, globular cluster, Serpens Caput

A beautiful sight with 5 Serpentis in the same field. Once again, V84 was at least as bright if not brighter than V42. Otherwise the cluster appeared much as it did on Tuesday night.

5 Serpentis was comfortably split at 92x. The companion star seemed a little brighter tonight; perhaps the transparency was better.

NGC 5921, galaxy, Serpens Caput

Small, faint fuzzy oval next to a y-shaped (or h-shaped, depending on your field orientation) pattern of field stars. Brighter towards the centre with averted vision.

NGC 5970, galaxy, Serpens Caput

Ghostly oval glow just south of a bright field star. Gradually brighter towards the centre with averted vision. Nice yellow-blue double star to the east (identified in NSOG as Otto Struve 300).

NGC 5962, galaxy, Serpens Caput

Round hazy glow with a bright core. Star-like nucleus with averted vision – seemed slightly offset to the east.

M13, globular cluster, Hercules

The 13mm Ethos doesn’t necessarily give the “best” view of globular clusters (in terms of resolving fine detail and pulling out the fainter stars), but it often gives the most beautiful, the Great Globular in Hercules being a prime example. When you see it in such a wide field that the field stop effectively disappears from view, it’s like being out there in space with it. And there’s always something new to see if you look carefully enough. For example, tonight I noticed two lines of stars running through M13 (parallel to the two 7th magnitude stars flanking the cluster). One running straight through the centre, and the other slightly offset to the southeast, adjacent to one of the arms of the propeller feature (adding to the contrast effect). 

By now the patchy clouds advancing from the south had covered nearly half the sky, pushing me farther north.

NGC 6015, galaxy, Draco

One of the galaxies I missed the other night. Appeared as an extended lenticular haze east of a field star. Brighter towards the centre with averted vision.

With the clouds pushing me still farther north, there was just time for a quick look at Nova Cassiopeiae 2021 (aka V1405 Cas), which has brightened dramatically in recent days. (See: https://skyandtelescope.org/astronomy-news/observing-news/nova-in-cassiopeia-brightens-suddenly/ )

I didn’t have a finder chart to hand so I had to identify it by comparing the field stars on my atlas to the ones visible in the finderscope. Fortunately it stood out really well at around magnitude 5.5. The Ethos showed it in the same field as rich open cluster M52. A very nice appetiser as I wait for my elusive first supernova.

At this point it seemed like the patchy clouds might leave some clear sky behind them, but then the wind abruptly reversed direction and an even thicker bank of cloud rolled across from the north, putting an end to the session.