mikeDnight

Also made on the 2 & 4th April are these two quick sketches of the lunar crater Bettinus south of Tycho. This first quick sketch was made with an increasingly aggressive jetstream hindering finer detail and making higher magnification all but impossible. Again a sketch of Bettinus from the following night with a more stable atmosphere, but still not truly steady. The same magnification of 128X was used and again the sketch was made in a relatively short time. The crater floor on this occasion appeared to be relatively featureless except for a couple of brighter areas and a fine rille or fracture extending from the northern rim to the central mountain peak. This was a very subtle feature on this occasion. Perhaps a steadier atmosphere and higher magnification will show it better on future occasions?

Here are some observations for 2 & 3 April 2023. It seems to have been cloudy forever and so to get two clear nights was quite a thrill. The view of Venus on 2/4/23 was made under less than ideal conditions, as the jetstream played havoc with the image, causing the planet to dance violently at times. However, in moments of reasonable steadiness detail did come into view, though fleetingly. The use of the Wrattan 80A blue filter helped settle the agitation and also helped highlight the bright areas. The following night (3/4/23) was much more settled, and so I made several sketches of Venus using both integrated light an with various colour filters. It was interesting in the final two sketches that the dark red #25 filter and the higher power unfiltered view revealed a bright spot set against the already bright northern limb. Perhaps as both filter and higher magnification effectively dimmed, and in the latter case enlarged the image, it made seeing this high cloud feature stand out more easily?

Thanks Kon, I'm loving your superb images! They are showing a completely different level of detail than that seen visibly through the eyepiece, yet still relatable, which is encouraging to me. The detail through the eyepiece is very subtle and so to show it in a sketch, the sketch is naturally needs to be an exaggeration with regard to intensity. However they do show what I believe is in the eyepiece image. Last night I decided to spend some time using colour filters and comparing the views with that of the unfiltered view. Colour filters really do help at times, but as you can see in the sketches below, different colours reveal slightly different levels of detail. I also noted that increasing the magnification in the final unfiltered sketch helped reveal some of the detail more easily. There is also a bright spot on the limb that was seen using the red filter, which is quite dark for my small aperture scope, and which was also visible at higher magnification. Possibly a high cloud on the limb that's catching the Sun? Anyhow, it may be the dimming of the image in both cases, one through a dark filter and the other through a higher magnification that allowed the bright spot to stand out against the already brilliant limb? Sounds plausible to me!

I've often seen colour on the Moon, particularly orange around some craters, due to tiny glass beads, and also subtle blues. looking at the Moon when near full will show it certainly isn't monotone.

Although it was a clear sky, the jetstream ruined the view. To help settle the turbulence in the eyepiece I used #80A blue filters (which help to bring out the visually brighter regions) on Venus, and I could only manage low powers on the Moon.

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I'd sell my wife and kids to get one. That should pay for the dovetail, so at least I'm part way there!

My FS128 tube assembly with tube clamp, Mewlon dovetail, and 50mm finder & bracket cost me £3,850 from TruTek in early 2003. The FS152 at that time was around £10,200.00, and the FS102 was around £1,750 I think. Here are a few mouthwatering catalogue images from the past, just to get your hearts pounding. And then there was this- Nick Hudson at TruTek was a truly great man who'd go to great lengths to deliver a great price. My FC100DC & FC100DZ invoices are proof of that.

You have a cruel sense of humour Dave - possibly worse than mine! I miss my FS128!!

False colour when observing Venus can also be due to atmospheric dispersion even in colour free systems. So an ED may show more colour than a fluorite or triplet apo, merely because the image can lose critical focus momentarily because of the turbulent atmosphere. Complex wide angle eyepieces can often show lateral colour more readily than narrower field eyepieces. Its often better to observe Venus while its still quite high and set against a blue sky.

Just thought I'd post it with it being April 1st. The jokes on me though as I should have done it this morning. Never mind, at least it got your heart racing, and you know deep inside that Takahashi will eventually hit us with a 5" fluorite just when we're at our weakest. Sorry Gerry, I feel mean now! What a rat-bag!!

Get your piggy banks ready!

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SGL imager Kon posted these wonderful images a few days ago. When I study any of the albedo features I almost always start by noting the brighter regions, then gradually add the duskier detail. Kon's images show bright areas corresponding to those of the sketch, which to my mind is proof of their reality. I didn't use any colour filters.

Very often the detail on planets such as Mercury and Venus are so very subtle that its easy to doubt. However if you can see hints of detail on Mars while its currently under 7" arc, you should be able to see dusky or brightish regions on Mercury. The trouble really is that the atmosphere often causes the image to dance. Sketching can help as its a bit like stacking images. As a suspected patch appears momentarily jot it down, then add to it as more detail flashes into view. It always amazes me that the end result, more often than not, relates quite well to the real surface detail. I've never seen any hint of detail on Neptune, but back in the mid 2000's, I made an observation of Uranus that revealed an unusually bright polar region. The pole at the time was tilted slightly toward us. The sketch was published in the SPA journal along with an image made by a fellow SPA member at the time that confirmed beyond doubt the pole was unusually bright. The point is that I drew what I saw not knowing if what I was seeing was factual or not, but it turned out to be real. More recently, while sketching the lunar crater Werner, I noticed the finest rille extending from one of the central mountain peaks, across the floor and up the terracing then out across the rough terrain. I was told by observers more expert than myself that no such rille existed. Further observation revealed two more rilles inside Werner, and I can see all three virtually every time I study it. It was a BAA member who sent me an image showing my initial rille. And more recently after buying the Duplex Moon Atlas, to my great relief I can just see all three of my Werner rilles as what I now believe to be the finest collapsed lava tubes. It's incredible that a 100mm refractor revealed what, to my knowledge, hasn't been seen in larger telescopes. It's easy to doubt, but we shouldn't!

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Below is a map of Mercury that may be helpful for observers. It was made by an accomplished observer using an 8" SCT, but smaller apertures are also very capable when observing the planet's albedo features, and can often appear to be less troubled by the increased turbulence due to the planet's low angle. The use of coloured filters such as #80A blue & #21 orange work well in enhancing lights and darks respectively. And binoviewers will also aid in simmering down any turbulence and enhancing any detail. What to expect through the eyepiece -

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Sky & Telescope produce a laminated map of the Moon. You can choose from with south top as seen through a reflector, or a north top image reversed option. I use the latter Every time I observe the Moon and its excellent. However, if you want a truly excellent atlas that shows a refractor view, then the Duplex Moon Atlas is very impressive. The images below don't do justice to either the map or Atlas! S&T laminated (north top, E/W reversed for diagonal users) Duplex refractor/Mak, SCT, & Cassegrain maps, and Newtonian reflector maps. One of the best, highly detailed atlases I've seen.

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Sky & Telescope produce a laminated map of the Moon. You can choose from with south top as seen through a reflector, or a north top image reversed option. I use the latter Every time I observe the Moon and its excellent. However, if you want a truly excellent atlas that shows a refractor view, then the Duplex Moon Atlas is very impressive.

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