Exploring Ophiuchus

1-2 June 2021, 23:45 – 02:00 (BST)

Seeing: Poor – Very Poor

Transparency: Poor to average (varied from one part of the sky to another)

Conditions: Mild again, although it started cooling noticeably from 00:45. There was no wind to speak of for much of the session, but it picked up suddenly towards the end, becoming quite breezy. No condensation. Overall the transparency was still poor, but slightly improved compared to the previous two nights.

I had planned to revisit some planetary nebulae and globular clusters at high power, but the seeing was so bad (even after allowing plenty of time for the scope to cool down) I ended up leaving the 9mm Nagler (133x) in the focuser for the entire session. After warming up with a last look at M5 before it disappears into the summer murk, I moved east to Hercules and Lyra, where the sky seemed like it might be dark enough to track down some faint targets.

NGC 6703, galaxy, Lyra

Small, faint round haze in a rich star-field in northern Lyra. Brighter core with averted vision. Plotted in SA2000 but not the PSA.

NGC 6482, galaxy, Hercules

Condensed round haze (fairly small) with a bright, star-like nucleus. Forms an isosceles triangle with two 12th magnitude field stars. 

M4, globular cluster, Scorpius

At least I could see it tonight, but the view was far from impressive. Some stars resolved when the seeing allowed, including the distinctive central bar, but most of the time it looked mushy.

M107, globular cluster, Ophiuchus

Large and faint as globulars go. Brighter towards the core, but not particularly condensed. Grainy with averted vision, but no stars popping out (the seeing didn’t help in this regard). The cluster is surrounded by five field stars which make up a distinctive kite or cruciform shape.

M14, globular cluster, Ophiuchus

Quite large and bright, but again – not particularly condensed. Speckly with averted vision. A few stars resolved on the outskirts – most prominent of these were two on the WSW side of the cluster (part of a possible chain of four or more stars leading away from the core).

NGC 6284, globular cluster, Ophiuchus

Round fuzzball with a condensed core. No stars resolved, but quite prominent despite its low altitude (-25 degrees declination).

M19, globular cluster, Ophiuchus

Large and bright; grainy with averted vision, but poor seeing prohibited resolution of individual stars.

NGC 6287, globular cluster, Ophiuchus

Faint round blur; some brightening towards the centre. Hint of graininess with averted vision.

NGC 6369, planetary nebula, Ophiuchus

Faint round disc of light, modest in size (listed at 28 arcseconds). Seemed brighter on the western side, with a hint of annularity, but the detail was smeared out by the poor seeing. At -25 degrees this is one of the most southerly planetary nebulae I’ve looked for, so I was pleasantly surprised I was able to see it without a filter.

NGC 6517, globular cluster, Ophiuchus

Faint round haze. Bright core with averted vision; seemed slightly elongated on the north-south axis.

It was at this point that the breeze started picking up, shuffling the pages of my notebook and threatening to do the same to my sky atlas. There are two other globular clusters plotted near NGC 6517 (NGC 6539 and IC 1276), but I couldn’t see either of them – presumably because of low surface brightness. But I did have better luck with another globular cluster farther north.

NGC 6535, globular cluster, Serpens Cauda

Soft round glow residing in a rich star-field. Seemed slightly misshapen on closer inspection. Not very condensed, but about half a dozen stars popped out with averted vision, the brightest one on the southwest side. If I didn’t know better I would have thought this was a very rich open cluster rather than a globular (given that in most NGC globular clusters I’m lucky if I resolve one or two stars). I’d like to see this one again under a darker sky. A nice note on which to end the session.

3 Open Clusters and 3 Globulars

31 May 2021, 00:10 – 01:20 (BST)

Seeing: Poor

Transparency: Average – Poor

A mild night to begin with, but cooled gradually over the course of the hour. Also a little breezy. As the temperature dropped, the condensation grew, collecting on the telescope tube and softening the pages of the notebook. The absence of true astronomical darkness was also apparent, making me wonder how I managed to see so much last summer (perhaps the light pollution from the town centre is starting to return to pre-2020 levels).

I started with a look at three open clusters in western Cygnus, two of which I’ve seen before (but only in passing, judging by the brevity of my notes).

NGC 6811, open cluster, Cygnus

133x. Large mass of similarly bright stars near Delta Cygni (and within the Kepler space telescope field of view); shaped vaguely like a fat spinning top, or an arrowhead. Hard to separate from the rich Milky Way background at this magnification; would probably look better in the Ethos.

NGC 6866, open cluster, Cygnus

133x. Compact group of about two dozen bright stars arranged in winding chains, with an underlying haze of fainter members. Quite pretty.

NGC 6819, open cluster, Cygnus

133x. Another compact cluster, shaped a bit like a wishbone or a pair of pliers. Comes alive with averted vision; revealed as a rich spray of faint stars with what looks like a dark lane cutting through the centre of the cluster. The wishbone suddenly becomes a flying squirrel(!), gliding through the Milky Way. Very pretty cluster; worth revisiting at a higher magnification on a better night.

M80, globular cluster, Scorpius

133x. Grainy round glow with a bright core; averted vision appears to expand the size of the cluster. 8th or 9th magnitude field star to the north-east. At 171x the impression remains much the same: a very condensed core and a few “speckles” with averted vision. The most prominent of these speckles (and the only one I was able to hold in view for a significant amount of time) was roughly halfway between the core of M80 and the aforementioned field star.

M12 and M10, globular clusters, Ophiuchus

133x. Both clusters looked a little washed-out tonight, and even increasing the magnification to 171x didn’t make much, if any, improvement to the contrast. (I think to see them at their best you really have to stay up very late on an April night.) Of the two, M10 looked better from an aesthetic point of view, appearing rounder and more condensed. M12 appeared unruly (almost “messy”) by comparison, with 2 particularly bright stars south of the core. As noted last year, the southernmost of the two is so prominent I wonder if it might be a foreground star.

With a waning gibbous moon starting to rise in the southeast, this was always going to be a truncated session, so I rounded off with a quick look at M11, which still looked superb despite the brightening sky. See my article on Love the Night Sky for more on this magnificent cluster.

With a similar forecast for the following night I took the scope out again (31 May, 23:45 to 1 June, 01:00), but, despite the moon rising half an hour later, the sky transparency was even worse. M4 (which looked so good last year) wasn’t even visible above the background glow.

Given the unfavourable conditions, I didn’t bother taking detailed notes, but I did look at M56 in Lyra, plus M80, M12 and M10 again (at 133x). I also looked at M57 and M13 at 333x (9mm Nagler + 2.5x Powermate), but the seeing wasn’t really good enough for such a high magnification.

As usual for this time of year, the sky was alive with satellites, including two bright ones which raced through the field of view while I was looking at M10 and M57.

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.

Globular Clusters in Hercules and Galaxies in Draco

11-12 May 2021, 22:45 – 01:15 (BST)

Seeing: Average

Transparency: Average

A breezy night with occasional gusts. Some high cirrus cloud early on; this blew away and the sky remained clear until about 1 AM. It had been a warm day, so the temperature was relatively mild at the start of the session, but it soon fell away and became quite chilly by the end. No condensation though.

Satellites and space junk everywhere I looked (including through the eyepiece). More planes than last year too.

At this time of year I always find myself drawn irresistibly towards globular clusters (no matter how many times I’ve seen them before) so I began the session with a tour of some of the season’s best.

M5, globular cluster, Serpens Caput

133x and 171x. As per previous observations: lovely, well resolved cluster with a bright, condensed core. Its stars seemed to have a considerable spread of magnitudes, with the most prominent member lying just southeast of the core. Another slightly less bright star is offset to the SW, forming a tight triangle with two other fainter stars. Reading up on M5 the next day I learned that both of these bright stars are variables: V84 (an RV Tauri star) and V42 (a Cepheid) respectively.

See: https://skyandtelescope.org/observing/hunting-bright-variables/

Another distinctive feature was a chain of stars curling around the NE side of the cluster, like a spiral arm. Not a great deal of difference between the two magnifications, but the stars did seem to “pop out” more at 171x. No colour to the cluster (or its individual stars) that I could perceive on this occasion.

While at 171x I also had a look at the nearby double star 5 Serpentis, comprised of a bright white primary and a dim secondary roughly NE. The secondary seemed to have a pale violet/indigo(?) hue, but it was very subtle and mostly likely caused by a contrast effect with the primary.

M13, globular cluster, Hercules

171x. Tonight M13 looked like a sprawling sea monster compared to M5. No individual stars stood out from the crowd, but there was good resolution across the face of the cluster. It took me a few minutes to “get my eye in” before I could spot the Y-shaped propeller feature, but once I did it was quite obvious. Nearby galaxy NGC 6207 (with its false nucleus) also showed well at 171x.

NGC 6229, globular cluster, Hercules

171x. Small and ghostly compared to M13. With averted vision the cluster swelled in size, and the core glowed with a soft intensity. After a few minutes of observing the cluster started to look a little mottled around the centre and grainy on its outskirts, but no stars were resolved other than a very faint star trailing to the east, of which I had only fleeting glimpses. (Most likely a foreground Milky Way star.)

M92, globular cluster, Hercules

171x. A bright, underrated globular with a very condensed core. Lots of stars resolved at 171x, but the oval shape noted previously starts to break up, although the area around the core still appears somewhat elongated. Other distinctive features include two straggly arms of stars roughly trailing to the north and south, and another tighter one folding back on itself east of the core.

NGC 6543, Cat’s Eye Nebula, Draco

171x and 133x. Another late spring/summer favourite. Impression much the same as last year: vivid, pale green ellipse – slightly misshapen. The central 11th magnitude star wavered in and out of view using direct vision, sometimes holding steady for several seconds at a time depending on the seeing. The view at 133x was similar, but the green colour was more intense.

NGC 6503, galaxy, Draco

133x. (The one that Herschel missed.) As per previous observations. Extended ellipse; not much brightening towards the centre, other than a vague impression of mottling/clumpiness.

NGC 6340, galaxy, Draco

133x. Round fuzz (fainter than 6503), roughly east of a double star. Star-like nucleus with averted vision.

NGC 6643, galaxy, Draco

133x. Faint streak of light east of and parallel to two field stars. A little brighter towards the centre with averted vision. This one looked like a ghost of NGC 6503.

While in the area I noticed a very distinctive W-shaped asterism in the finder, near 44 Draconis and later identified as Kemble 2. The eyepiece view revealed a few more stars in addition to the core five, but the best view was through the 9x50 finder.

Psi Draconis, double star, Draco

133x. One I’ve been meaning to revisit for a while (I always get distracted by the Cat’s Eye Nebula). A really lovely, bright double – at 30 arcseconds, wide enough to split (barely) in the 9x50 finder. In the main scope it appeared as a pale yellow-white primary with a pale blue-white secondary.

I couldn’t find galaxies NGC 6412 or NGC 6140 for some reason, though I suspect some high hazy cloud was starting to interfere with the transparency. With more clouds gathering low in the southwest (and a fox barking very loudly from the same direction), I decided to round off the session with another old favourite at a very high magnification.

M57, Ring Nebula, Lyra

428x (7mm DeLite + 2.5x Powermate). At this magnification the target crosses the field of view so quickly you need to get the scope ahead of it to give yourself time to have a decent look. The inner part of the ring looked a little ragged at this power, but unsurprisingly there was no sign of the central star, not even a hint of a glint. I think I’d need an equatorial platform (and near-perfect conditions) to stand even a chance of picking it out from the gauzy central region.

As the bright clouds pushed across the sky there was just time for a quick return visit to M13 at the same power. The sheer volume of stars was a little too much to take in during the short time available; at this magnification it looked less like a sea monster and more like a hanging basket brimming over with bright and unruly flowers; the entire field of view clotted with ancient starlight.