💾 Archived View for koyu.space › mrael2_obsv › sessions › 2018 › 2018-03-23.gmi captured on 2023-03-20 at 18:55:11. Gemini links have been rewritten to link to archived content
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Date: 2018-03-23
Time: 7:42 PM - 8:15 PM
Seeing: II - IV
Transparency: 7
Object: Mercury
I spotted Mercury at 7:42 PM lower than before in much brighter twilight. I decided to use a lower power than before to compensate for poor seeing so close to the western horizon, and sure enough I had better views at 84x with a clear waning crescent on the planet's surface.
Online references say that the phase is less than 20% lit, but poor seeing suggested a phase of about 35-40%.
Seeing was much better than before in part due to my usage of the cooling fan on the Dobsonian's mirror. It's the first titme I ever used the fan -- nearly three years after buying the scope.
As Mercury got lower, the phase appeared to change. The thicker atmosphere took the appearance quickly from a crescent to about 50% lit. And even this began to shift into more of a gibbous appearance.
By 8:05 PM, all phase information was lost, but the atmospheric instability as viewed at 84x did not cause the same turbulent roiling that I saw on previous night at 139x. Instead, the lower magnification produced a slow-motion roiling that distorted the planet into oval shapes and other blob-like appearances. The planet exhibited amoeba-like morphing from one shape to another as it continued to drop, and it simultaneously morphed in color as the red and violet fringing mixed and spread from edge to edge. It did not appear to be a planet by the time it set behind clouds at the horizon at 8:15 PM. It was a brilliant orange color just before setting (in the finderscope). I hope to see Mercury and slimmer crescents in these last few next evenings.
Venus started out very well defined, but it also became roiling and blurred as it got closer to the horizon.
Time: 8:40 PM - 9:05 PM
Seeing: I
Transparency: 6
Object: NGC 2360
This small open cluster is dim and fuzzy at 42x, but at 84x is nicely defined with a central concentration of stars that resemble not quite a series of concentric circles but a pattern that reminds me of the heart of an artichoke somehow. At 84x, a nearby bright star appears in the field of view with the cluster's center at the other edge. The cluster's core has 50-100 stars, but more stars comprise the not-clearly-defined outer borders. Nice!
Time: 9:15 PM - 9:18 PM
Object: Basel 11A
This extremely small open cluster is defined by a bright central star and a small number of surrounding stars that are very dim at 84x. Averted vision gives an appearance of a cloud of stars surrounding the central star. Higher magnification may improve the view as would a darker sky. Tonight, the Moon is a waxing crescent that is very close to 50% lit, so this open cluster should be re-observed under Moonless skies.
Object: NGC 2423
NGC 2423 is a small open cluster that is dim and fuzzy at 42x. At 84x, several dim stars are spread widely and uniformly through the field of view. Right next to M4?
Object: M47
M47 is spectacular! At 42x, the open cluster reminds me of the Orion constellation. Three stars at the cluster's center form a "belt," and above the belt is a triangle of stars that suggest a head. Below the belt are two bright stars that can be thought of as the "feet." The 2 stars of the feet combine with 2 other bright stars below them to form something of a trapezoid. At 84x, all the stars become bright and sparkly! Wonderful!
Time: 9:50 PM
Object: M46 in Puppis
At 84x, this open cluster has a number of not-bright, uniformly distributed stars that form mostly a circular shape. The stars have similar magnitudes throughout, leading to a uniform appearance.
Towards an edge of the cluster, planetary nebula NGC 2438 is clearly visible. It is a small circular cloud that obscures perhaps 5% of the cluster. It is easily seen with direct vision, but averted vision enhances its cloud-like appearance. On a dark night with no moon (and greater magnification) it may be an interesting object to explore further. Very neat due to its presence within an open cluster!
Time: 10:09 PM
Object: M93 in Puppis
At 84x, this open cluster fills the eyepiece with a few dozen evenly distributed stars of similar, non-bright magnitude. The stars are scattered and form no discernible shapes or patterns. Pleasant but non-descript.
Time: 10:20 PM
Object: M42
Even with the Moon close to 50% lit, the nebulosity of M42 was still quite striking tonight.
Also, at 84x, there was clear nebulosity around the stars of the Pleiades (M45).
The Moon itself had the terminator along a ragged and crusty edge that consisted of numerous craters and mountains. The contrast between the dark shadows and bright plains was fascinating. After my interest in deep-sky objects diminishes (if ever), I will likely become obsessed with the details of the lunar surface. In the meantime, only 25 more Messier objects to go!