I had a fantastic visual session last night!
Time: 22:50 local time (EDT); 02:50 UTC (08-03)
Cloud Cover: None
Wind: Very Light
SQM Measurement: 20.93
Transparency: Average (3/5)
Seeing: Good (4/5)
Length of Observing Session: 2h 15m
Instrument: Orion XT10 Plus (fl 1200mm, f/4.7); Paracorr Type 2 (effective fl 1380)
Eyepieces: Explore Scientific, Meade PWA and UWA, and Vixen SLV
Summary: The sky forecast was actually accurate for a change—no clouds, very light wind, and good conditions. I wanted to hit a couple targets in Scorpius and Sagittarius, then get a good visual look at Saturn and Jupiter if time permitted.
M7 (Scorpius): At 40mm (34x), Ptolemy’s Cluster was readily spotted. Approximately 40 stars were visible; the Cluster appeared loosely arranged. I noted three lines or gentle curves of stars running roughly east-west in the cluster, all composed of some of the Cluster’s brightest members. The northernmost arc consisted of five stars, and was very obvious in the view. The target filled about 40% of the field of view (at 68 degree AFOV). At 28mm (49x), the quality of the view improved. I counted about 50 stars, most of which were strong and steady—a testament to the Good Seeing. Most the brightest member stars seemed to shine with a very subtle blue tint, save one that shone distinctly reddish at the cluster’s northwestern edge. At 20mm (69x), the extra magnification definitely enhanced the view. Still approximately 50 stars visible, but the Cluster filled about 50% of the field of view (at 82 degree AFOV). The stars in the Cluster still shone with a rock-steady light. At 14mm (98x), the Cluster was framed very nicely in the field of view. I spent some time here just simply admiring the view. The red-tinted star in the Cluster’s northwest was quite prominent. I decided against pursuing greater magnification, since this would likely provide a less-pleasing view without the space around the target to provide context for the Cluster.
M6 (Scorpius): At 40mm (34x), the Butterfly Cluster was easily acquired. The target appeared to be composed of mostly dimmer stars, but had one brighter red star on its eastern edge. The curving arcs of the member stars were arranged in a manner that suggested its namesake. However, my immediate impression was not of a flying insect, but rather a fireworks burst. At 28mm (49x), the target’s member stars remained rock-steady. The extra magnification, though, diminished the butterfly-like outline the Cluster suggested earlier. However, more stars could now be seen, making for a beautiful view. At 20mm (69x), the Cluster was nicely framed in the view. The red star on the target’s eastern edge seemed to shine like a bright beacon—the brightest star visible in the Cluster. Very cool. At 14mm (98x), the Cluster was beautiful. Approximately 80 stars were counted, with the target filling about 65% of the field of view (at 82 degree AFOV). Spectacular. Again, I decided against pursuing higher magnification for this open cluster.
M22 (Sagittarius): This large globular cluster was easily spotted at 40mm (34x). Even at this low magnification, the cluster was breathtaking, appearing as a milky ball of stars. Many member stars were already resolved, especially the dimmer members along its extremities. The target displayed a large core area. At 28mm (49x), the greatly increased number of visible stars literally caused me to gasp. The core remained large in appearance. Averted vision showed countless stars—incredible view! At 20mm (69x), the target provided an amazing view. Brighter member stars appeared to overlay a dimmer bed when using averted vision. These brighter stars resembled spilled diamonds. At 14mm (98x), the “spilled diamonds” effect was now directly visible. Averted vision further enhanced this impression. The core still appeared large and bright. At 8.8mm (156x), some darkening was noticed in the view, but the target remained a splendid sight. The sheer number of stars visible in the field was staggering! At 5.5mm (250x), the additional darkening of the view removed some of the dimmest members from sight, but the view remained impressive nonetheless.
M28 (Sagittarius): At 40mm (34x), the target was spotted. The globular cluster appeared quite small and fuzzy—the polar opposite of the prior target. No stars were resolved; the cluster almost looked more like an elliptical galaxy than a globular cluster at this magnification. At 28mm (49x), the target’s small, compact nature remained unchanged in the view. Averted vision was only just *barely* beginning to show resolved stars in the cluster’s periphery. At 20mm (69x), the cluster still appeared small and compact. Only a few member stars could be directly resolved, while averted vision revealed many tiny points of dim light scattered amidst the cluster’s periphery. The core remained fuzzy and unresolved. At 14mm (98x), additional stars were resolved in the target’s periphery, while the core remained an unresolved fuzz. All resolved stars appeared dim. At 8.8mm (156x), the target finally took on the more characteristic attributes of a globular cluster. The angular size of the cluster remained small, but a few stars in the core area could now be resolved. Additional stars in the periphery became visible, but never strayed far from the core. At 5.5mm (250x), the image darkened considerably and caused significant loss of detail.
Saturn: I debated with myself whether or not to remain to view the planets, but I could not pass up the opportunity for viewing them in such good conditions. I switched to the Vixen SLV oculars to coax as much detail from the targets as possible. At 25mm (55x), the ringed planet was already a beautiful sight. The rings were obvious, and several moons were already apparent. These included: Rhea close to the planet to the north, Dione to the west, Tethys to the southwest, and Titan a little farther out to the north-northwest. Some dark cloud banding could already be seen in the planet’s northern hemisphere. At 10mm (138x), the moons were confirmed. Several dark cloud bands could now be seen on the planet, and the Cassini Division was easily seen. Beautiful! At 9mm (153x), the cloud bands on the planet’s disc were more pronounced. The Cassini Division in the rings appeared darker, and was even easier to see. At 6mm (230x), the first signs of atmospheric distortion became apparent in the view, but was not bad. Aside from the increase in magnification, the view remained largely unchanged—still incredible! At 5mm (276x), the focus began shifting in the view, but occasionally still afforded a fantastic view. I caught glimpses of what appeared to be additional grooves in the planet’s rings, inferior to the Cassini Division. These must have been coloration differences between different bands of the rings. Outstanding!
Jupiter: At 25mm (55x), the North Equatorial Belt was already clearly visible. The Southern Equatorial Belt was sometimes visible through the planet’s glare. (I considered getting out filters to draw this out, but it was getting late and I needed to bring the session to an end soon.) Three of the Galilean moons were visible to the planet’s west. Moving outward from the planet, these were: Io nearly hugging the planet’s western limb, Ganymede some distance outward, and Callisto farther out still. At 10mm (138x), the NEB appeared incredibly detailed, showing various shades of brown throughout, and even appearing red in places. The North Temperate Belt was also now visible, and the South Temperate Belt was revealed in occasional glimpses. At 9mm (153x), a distinct dark spot was seen just north of the NEB, along its western region, separated from the Belt by the thinnest gap—very cool. The detail apparent in the different cloud bands was nothing short of amazing. The Zones between the belts showed up very well, especially between the NEB and SEB, where it took on a tan color, with striations and variations throughout. At 6mm (230x), the view showed the first signs of softening, but the view remained impressive. No new details could be drawn out.
Conclusion: This session ran longer than wisdom dictated it should (especially with work looming the next day). However, it was still time well spent. The Good Seeing is something I don’t encounter very often, and I am glad to have taken advantage of it. My only regret is the necessary premature end to the session; if I had not had to work the next day, I would have stayed out all night!
Until next time!