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.
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.
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