The Southernmost Messier Object

14 June 2020, 00:30 – 03:30

Conditions: Mild, still (no wind), hazy and humid – heavy condensation. Cloud increasing over the course of the session.

Seeing: Average / poor
Transparency: Poor

I don’t normally observe in the two weeks either side of the summer solstice because the sky doesn’t get reasonably dark until gone midnight – and it doesn’t stay dark for very long. However, if I’m to do justice to the Scorpius/Sagittarius region I figured I should at least try to observe some of the brighter objects this month rather than tackle them all in a mad scramble in July or August. (And of course there’s no guarantee the skies will be clear then anyway.)

Also, encouraged by my glimpse of M7 last time out, I had the TV60 set up on the Super Polaris mount. However I hadn’t taken into consideration just how much the trees and plants can grow in barely a month, so I was contending with foliage as well as the neighbour’s fence. Fortunately, the TV60 is easier to move from side to side than the XT10.

After warming up with a look at M13 in both scopes (it appeared hazy and a little washed-out tonight, despite being nearly overhead), I switched to the main target for the evening.

M7, open cluster, Scorpius, 40x (TV60 + 9mm Nagler)
The scope was almost horizontal, but I was able to get just enough clearance over the neighbour’s fence to centre M7 in the field of view. The object itself appeared faint and washed out, but enough stars were visible to at least give a sense of a very large, splashy open cluster. The brightest stars seemed to form a distorted x-shape with a double star at the centre (although the atmospheric distortion and low magnification made it hard to split). There was also a haze of unresolved stars, plus an incomplete ring of brighter stars surrounding the central cluster. Even if M7 were high enough to be visible in the XT10, the TV60 would still be a better choice of scope to view it simply because of the larger field of view (2 degrees in the 9mm Nagler). By comparison, M6 – which is itself a fairly large cluster – appeared more traditionally condensed at the same magnification.

I also had the XT10 set up in the garden, but another thing I hadn’t taken into consideration was how bad the condensation would be tonight. I had planned to use the 13mm Ethos, but unfortunately the eye-lens misted over while I was looking at M7, so I swapped it out for the 9mm Nagler. The sky was getting hazier too, so I stuck to only the brightest objects. (The fainter stuff could wait for a better night.)

M21, open cluster, Sagittarius
133x. Loose, bright cluster, a little north of M20. Star pattern at centre in the shape of a teacup, or a backwards “3”.

M23, open cluster, Sagittarius
133x. Rich, large cluster. Uniformly bright stars filling the fov. Bright star to north. Concentration of fainter stars at western end of cluster.

M25, open cluster, Sagittarius
133x. Bright, large cluster, with a distinctive “D” shaped pattern of stars at the centre. Unlike M23, the stars come in a mixture of brightnesses.

With the condensation worsening and the sky already starting to brighten, it was almost time to pack up. However while taking the TV60 indoors I noticed that Jupiter and Saturn were starting to emerge from behind the tree, so I (carefully) moved the XT10 and changed the 9mm Nagler for the 7mm DeLite.

Jupiter, 171x: the seeing was variable but in the fleeting moments that it steadied, the DeLite gave a very sharp, comfortable view. All four Galilean moons were on view and I could see the Great Red Spot moving onto the disc, showing its familiar brick-red colour when the seeing allowed.

Saturn, 171x: Titan and three faint moons were visible, despite the brightening sky. Saturn was its usual exquisite self with the Cassini Division showing well in moments of good seeing, as well as the shadow of the planet on the rings, and the dusky equatorial band.