Nik271

What's the focal length of you telescope? A finderscope has field of view between 7 and 5 degrees. This helps a lot with star hopping with stars which you may not see with naked eye. I would recommend getting a 9x50 finder, you will see a lot of stars in it. To match the view in this finder with 32 mm 1.25 inch eyepiece your telescope needs to be under 300mm focal length. Of course you can still get by with eyepiece only but the star hops need to be short, up to a degree or two at most.

Great animation! The corona is a sight to behold, I saw it once in 1999. The next 'accessible' total solar eclipse in on 8 April 2024, with totality crossing Mexico and the USA. I'm sure by then long haul travel will have resumed. Probably it will be more expensive and less frequent but people will travel again, especially to see a solar eclipse. There will be one closer in Europe in 2026 ( best seen in Spain I think).

Just had a look at the new sunspot region 2859. After some quiet period for white light this one looks promising, it has umbral regions, penumbra and some bright faculae next to it. The seeing was good at 8:30am, with green filter and skymax 127 at 120x I could see details in the umbra and hints of granulation mottling on the surface.

I use Delta Cyg as a test of seeing when observing in summer with my 120mm small Mak. It's my second test, after the Double Double (which is a much easier one), then I go for either Delta Cyg or Izar to see if there is any point trying to split close doubles. The nice thing about these is you can split them even in the summer twilight, as the stars can be seen in the finder and are close to naked eye Vega, Deneb and Arcturus which appear just an hour after sunset.

Its so simple to deal with light pollution, especially with modern street lights which can be remotely controlled. Lighting costs can be something like 10% of a town electricity bill and you'd imagine dimming the bloody things after midnight is a no-brainer, saves both energy and money. Hopefully with the projected energy price increases and the plan to charge cars and heat houses with heat pumps this should translate to a drive to save it at night for where its really needed.

Totally clouded here. It will be nice to have some increase in sunspots activity, has been a bit on the quiet side recently.

Looks a very nice set up! A big table is most convenient, it's begging for one of those small tabletop dobs for grab and go. By contrast I can read a large print book in the 'darkness' here in suburban Oxford. And just now they approved a plan to build 500 more houses and offices only a kilometer from us. There is a lot of local objections but of course money talks loudest and the plans were approved together with building roads in the green belt and what not. We humans will not be happy until we pave over everything and drive all else to extinction. Despite this there is a lot to see even with light pollution. I managed to view the nova RS Ophiuci yesterday, it has provided a lot of action recently.

I just managed a quick look in my finder. It's become much dimmer, I estimate it at mag 8. I only had seconds to view it between gaps in clouds, the only reason I spotted it quickly is because it is deep red. Amazing to see such a rapid change in colour!

Here is the direct quote from the article In defence of Lanigan the middle sentence is not a direct quote, so probably she was misreported. Most likely there were two statements, that oppositions last very short time and that the planet is visible with the naked eye. When they put them in one sentence it became garbage. Having dealt with journalists before I know it's very difficult to quality control what they actually publish. They always try to oversimplify and compress everything into soundbites. A friend of mine was attached one summer to a national newspaper in a science advisory role and despaired. All science stories had to be at most 50 words long to fit with the rest of the style of the paper. The BBC at least get good stuff now and then: https://www.bbc.co.uk/news/science-environment-57998940 Some reporters at least know their stuff and properly research a story.

I use a Sigma 70-200mm F2.8 for occasional astrophotography and I'm very happy with the results. I use mine wide open to save time unguided. I would say that if you stop down yes it will get sharer but then longer exposures need good guiding. Teleconverters usually ruin the sharpness and introduce aberrations, you may be better off with a camera with smaller pixels for the same result. Fogging up is not an issue for the coating, just leave it in a warm place for a few minutes to evaporate. Don't wipe it when its moist, because any bits of dust stuck on it will create mini scratches. Once dry you can clean it in the usual way blower, brush, lens cloth (if it looks very dirty). The main issue to watch out for with dew is not the coating but if you cap the lens with dew on it, the moisture will gradually work its way into the insides. Otherwise L-lenses are build to last so a bit of dew during the night should be OK. Just dry it thoroughly before storing. Refocusing is potentially needed with all fast lenses, because the tolerances are so fine. I check mine very hour or so - just look at the size of the stars. Most of the time it's fine unless there is a big temperature variation or I move to a different area of the sky. Anyway you should definitely give yours a go! Must be quite a beast at 300mm and F2.8

I think there is still demand for Maks and other compact scopes with folded light path and long focal distance. Main reason for disappearance of the Russian manufacturers I think is that a lot of that market has been cornered by the big Asian guys i.e. Synta and GSO which give reasonable to very good quality standard optics at lower price points.

I think that a 6 or 7mm EP is not an overkill for 8SE in situations where you want to zoom into some planetary nebula or the moon or some close double star. 2000/6=333, perfectly feasible magnification for a 200mm diameter telescope in excellent seeing. I use 6mm and 9mm Svbony red line EPs in my 180Skymax with focal length 2700mm. There is some kidney beaning on the moon, but hardly noticeable on dimmer objects.

The 130M has a spherical mirror so it's spherical aberration you should be worried about. I see that 130M has 900mm focal length, so its focal ratio is f/6.9. This is ok for low and moderate power views but you may find that when you use higher magnification the view will be somewhat soft. I think at 130mm diameter a spherical mirror should be at least f/8 to deliver comparable views to a parabolic one. I would recommend go for the 130P. More compact, lighter and the difference in focal length can be compensated with the use of a Barlow.

I find this interactive online atlas very useful to identify things that I see on the Moon: https://quickmap.lroc.asu.edu/ It uses the detailed maps from the cameras on the Lunar Reconnaissance Orbiter, plus all the other geological data it has collected.

They are named after Linne, the carter in the bright area in the lower left in your photo. Going from top to bottom they are Linne G,H,F, B,A and the last one in the line is unnamed. The crater on the lower right s Linne D. They are all 4-5 km in size and larger than Linne itself. Linne itself is named after the botanist Carl Linnaeus: https://en.wikipedia.org/wiki/Linné_(crater)

I was on the lookout for Perseids last night too (12 August) but did not manage to see a single one

Hi Sam, in good conditions I can use a 6mm EP on the Moon and double stars, which gives nominally x250. This happens rarely, most of the time I use 9mm or 10mm for high powers because the seeing does not allow more. Also the true magnification with the diagonal is higher than 1500/6=250 because I have measured that the Skymax has 1500mm focal distance at prime focus. When using the diagonal you should add a bit extra, perhaps another 120mm to the focal length. Nik

I had a quick look yesterday about 10:30pm with my 9x50 finder. It seemed to be 6.3 to 6.5, slightly more red than 2 days ago and almost a magnitude dimmer.

Very nice, John! I think a clean split will require more aperture, perhaps 6inch refractor or 7-8 inches for an obstructed scope because of the brighter diffraction rings. Dubhe gest behind a tree for me at this time of the year. I mean to look at it again in some autumn early morning, when it's well positioned. I was out last night but looking in the opposite direction to Ophiuci. Managed to split Tau Oph at 180x with the 180 Skymax. Separation is 1.4'' and the two components have almost equal brightness, so not really a tough double in good conditions but the seeing was so-so and made it challenging. I gave up on doubles for the rest of the evening and looked at some globulars instead. M13 was gorgeous, I could resolve stars down to the central core at x180.

The classical cassegrain is open tube so cooldown is not going to be an issue, especially for a 6 inch mirror. Dew should not be a problem either. I have used a 6 inch Newtonian in winter and had no problem at all. The CC is even better because the secondary mirror is facing directly back into the tube. S The refractors are slightly more versatile with shorter focal length and will not need collimation, so that's an advantage. If money is no object go for them, otherwise the stellalyra will give more value for money. Btw, why would you need an extra dovetail bar on the CC if you are doing visual?

There was a bit of haze last night but otherwise it was clear at 10:30pm and I managed to have a look with my Skymax 127. It was dimmer than Tau Oph but considerably brighter than the nearby Y Oph, so I will put it at mag 5.4 or thereabout. Hard to be more precise because the haze and low altitude was making everything dimmer than it should be. I took 20 photos with 85mm lens and stacked them. Here is the result. I have labelled the nearby bright stars from Ophiuci.

Thank you, Jeremy, I will check it out in the next clear evening (Tueday hopefully). It seems best viewed around 10:30pm from the UK, but only rises to about 30 degrees altitude. I was looking in this area just last week, trying to split Tau Oph and there was no sign of RS Oph in my 9x50 finder when star hopping. Looking forward to observing this fast brightening event.

I always thought that a travel scope is one that you are prepared to risk losing in transit without breaking the bank. If I had it I will need to keep this Borg in a safe in a bunker somewhere

This draft version looks very good to me already! I also observe double stars from urban skies and really appreciate this collection. Definitely going to order the printed version when available. One suggestion: the position angle and separation change over time and sometimes quite rapidly in just a few years. Perhaps you can mention this in the introduction for the novice who may not be aware of that, and give the epoch of the given data, I presume 2021. Nik

PS. Actually a pair of binoculars will be more useful to spot it first and once you know exactly where to look then use the Dob,