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.