Ganymede Jun 2, 2017

[pgc hunter]

With a massive strong high directly over SE Aus and a very cold frosty night, I headed out as I thought seeing might be on the good side. What I got was conditions at times where stars at 600x showed near-perfect airy disk and diffraction pattern that barely wobbled. The Galilean moons all appeared as satisfying disks at high power, without much in the way of "seeing hairs" that flare around the moons in unsteady conditions. However, Ganymede at high power appeared somewhat "gibbous", so I spent a good hour examining it at up to 600x. I could see what appeared to be a dusky feature just north of the equator, while the northern limb and the south-preceding region of the disk seemed to be higher albedo, certainly moreso than the following limb.

[Tropo-Bob]

Nice evening Sab, I am so envious. If there has ever been a night like that in Cairns, I missed it!

I am amazed that your 8 inch scope was able to show detail on Ganymede. Is it a stock-standard scope of something more fancy?

[Tinderboxsky]

A stunning result Sab. Very envious too.

I am also interested to hear a little about your scope. I recall you referring to it in a post a year or two ago but cannot recall the detail other than it was a longer focal length than today's trends.

Edit: f6 obviously as per your signature

[bigjoe]

Great work..you've got an exceptional scope or eyes or both..I now am inspired to try in my 10" SCT!

bigjoe

[pgc hunter]

This scope was actually made by Cris at Astronomy Alive in Melbourne and I bought it second hand. From what I understand, the optics in this scope are made by the same folks that make the optics for Takahashi and the tube is fully flocked. It's focal length is the standard 1200mm F/6. The tube is slightly longer than normal to avoid dew on the mirrors. The secondary is a tad large at 2.14" so I plan on putting in a 1.83" sometime down the track. It also needs a primary fan.



I think it was the seeing more than anything else. With a tiny 1.5" disk, it doesn't take much to blur Ganymede.