JamesF

9 minutes ago, Mark-V said:

Just set the sky box to record it !

Yup, set things up to record the series earlier today myself.

James

11 minutes ago, wimvb said:

Btw, does @Tomatobro have the original focuser on his MN190, or an upgrade?

On mine I have a motorised Moonlite, because that was what was fitted when I bought it.  Sadly rather like Göran, mine has been sitting on a shelf for some time, waiting for other work in the observatory to be completed.

James

1 minute ago, gorann said:

If it is not on the same mount, it does not count as a dual rig, does it?

A good point, well made.

James

4 minutes ago, wimvb said:

If I ever go for a dual rig, it may very well be with 2 * MN190. But not on the same mount.

  Two MN190's would squash many mounts.

James

26 minutes ago, Tiny Clanger said:

You never met my aunty Doris , obviously.

Not Doris "The Gripper" Brown, known throughout Warwickshire for her generous disposition and the warmth of her chinese burns?!

James

13 minutes ago, Stu said:

It’s like named storms, pure marketing hype to get attention and fill some column inches

The Met Office freely admit that they're naming storms so they get publicity with the intention that people will pay more attention and take whatever measures might be appropriate.

Then for some reason they go and give them names like "Storm Doris".  Who's going to be worried about Storm Doris?  You might as well call it Storm Chuckles.  Now, Storm Attila or Storm Genghis would have me panic-buying enough tinned food for a month!

James

1 hour ago, Alien 13 said:

I might even add a small rug...

That looks like something from a cartoon, where Roadrunner scoots straight across it when being chased by Wile E Coyote, who falls down the hole in the middle.

James

And then there's this piece of, errrm, well, I'm not sure how to describe it really.

https://astronomytechnologytoday.com/2018/06/28/miniwasp-parallel-imaging-array/

James

Someone pass the brain bleach!

James

18 minutes ago, woodblock said:

Another thing was at one point Sandra has to travel from the international space station to a Chinese spacecraft in an escape module by firing it's engines. "It's only a hundred miles" says George. " Just a sunday drive". So I thought that must be harder than it looked in the film and I ended looking up Hohmann Transfer orbits which are quite interesting.  I don't think you can just point and shoot even if the two craft are in the same orbit. I don't think it works like that.

I found something interesting about Hohmann transfer orbits. Suppose you want to go from a low orbit to a high orbit. The speed for the high orbit is lower than the speed for the low orbit but in order to go from low to high you have to increase your speed twice. 

I've just read "Carrying  the Fire" by Michael Collins (the one who got to stay behind when Armstrong and Aldrin went down to the Moon's surface).  He talks about this, because obviously they had to practice docking as part of the preparation for the trip.  For Gemini 10 they had to dock with an Agena booster that had already been put into orbit and use that to boost themselves up to higher orbit and "catch up with" a second Agena booster from Gemini 8(?) where he performed an EVA.

His description suggests that it is certainly not a simple process to meet up with another object in orbit and you certainly can't just "point and shoot".

James

39 minutes ago, Louis D said:

That still requires a dead lift of 46 pounds to a height of about 2 feet.  I can just manage that, but it leaves me with a backache.  I don't know about the OP's back situation.  Hopefully, he'll chime in with a more specific weight limit.

Yes, I agree that not everyone will be able to manage that.  He does offer an alternative solution though

James

Here's the video.  He's showing off, and using a C14.  Perhaps he thought a C9.25 would be too easy.

James

Just now, Pete Presland said:

I didnt see the back reference, both of them are quite heavy. I am ok with the C9.25 at the moment, but in 10 years time though who knows? It is something that i think about more and more even at 54 yrs.

There's a video on youtube of a method for working around this problem for large SCTs, though perhaps it still wouldn't suit everyone.  I believe it involves putting the OTA "corrector down" on a chair or stool and then moving the mount axes to meet it.  I'll see if I can find it.

James

The roof is about 2.5m wide and getting on for 4m long.  I needed two rails (or nearer one and three quarters) end-to-end for each side.  This photo taking during construction probably gives you a better idea:

My entire build thread is here, if it's helpful.  There are a fair few photos.

James

I have to admit that I'd not thought of my V rails as noisy, but I have nothing to compare them with and I'm in the middle of nowhere anyhow.  It doesn't squeal or anything like that, at least.  Quite possibly the roof moving is quieter than a NEQ6 slewing at full speed :)  I appreciate the need to keep noise to a minimum when you have near neighbours though.

James

1 hour ago, Louis D said:

Many folks, myself included, find seated observing much more relaxing and enjoyable.

Definitely.  Nothing has made a bigger improvement to my enjoyment of visual astronomy than working from a comfortable seat.  I can't now imagine doing anything else.

James

I used FH Brundle for my roof rails, as already linked.  My roof is quite heavy -- I welded a steel frame and then fixed OSB to the frame before cladding the sides and covering the roof with EPDM (and it's about 2.5m wide by 4m long).  With a smaller, lighter roof I'd certainly be concerned about the wind lifting it off.  A shallow pitch roof acts like a wing in the wind and generates lift which can be sufficient to allow the entire weight of the roof to be overcome, at which point it flies off.  This has happened to SGL members in the past, even with a fairly substantial roof.

Using a C-section runner with the wheels inside, such as is often used for sliding doors, would keep the roof fixed down (one would hope), but may be a little more awkward to make, especially given the additional complexity of horizontal wheels as suggested by Peter (which I agree would be a good idea).  One of my greenhouses actually has a slightly more complex "C" section runner which has a "gulley" down the middle that the wheels sit in, effectively preventing them from wandering from side to side.  Something similar might remove the need for horizontal wheels.

Some of the benefits of using an open inverted V or semi-circular track such as quite a few of us have used are that there's no side-to-side movement to worry about, and the track is easy to fit and keep clear of debris (and potentially ice, which can build up if rain gets into exposed sections, or even form just as a result of condensation on cold metal subsequently freezing).  The negative side is that there's nothing to stop the roof lifting off other than its own weight.  Some people use turnbuckles or latches to hold the roof down when it isn't in use, and unlock them manually before opening up.  I used something similar to these: https://www.amazon.co.uk/Toggle-Action-Release-Holding-Capacity/dp/B075GZRK4K (the actual ones I bought don't appear to be listed any more).

Another option is to have some horizontal pins that slide into holes as the roof closes, thus preventing it lifting.  This allows remote opening of the roof, but ultimately you may still need something like the above catch to lock the roof firmly in place when bad weather is expected because you don't want it blowing open during a torrential rainstorm.  I don't know what other people have used, but I was toying with using some pins like the ones I have on my tractor implements to fit on a 3-point linkage when I get as far as automating my roof.  Quite possibly that's overkill

One thing to consider regarding freezing conditions: imagine water got into some part of the roller system on a winter day thanks to some blown-in sleet, and as darkness fell and the temperature dropped, producing a night of outstanding best-in-several-years clarity, you then found the roof wouldn't open because that water had frozen.  How easy would it be to clear the ice from your chosen design?

Ultimately I think I prefer the open rail approach because it's simpler to install and to use, but I see no reason the C-section runner couldn't be made to work if that's the way you prefer to go.

James

4 hours ago, Mark at Beaufort said:

we will meet again.

Some sunny day, perhaps?

James

Nice one.  Now you need a remote controlled finger to work the buttons on the remote

James

Somehow I have contrived to miss this one, but the images online appear to show a very pretty cluster so I shall certainly attempt to find it next time the opportunity presents itself.

Thanks to John for drawing it to my attention.

James

The retaining wall looks nicely finished.  Your own work?

James

Indeed.  Very nicely done.

James

Actually, on the topic of levelling, it has just occurred to me for the first time...

If my pier tops are absolutely level, and, say, Olly's pier tops are absolutely level (I bet if they are it's only by accident because I'm pretty sure he's not that fussed, but anyhow...), our pier tops will not be aligned with each other because I'm at 51°N and he's at 44°N (and in fact he's eight or nine degrees east of me, too).  However, once polar aligned, the RA axes of a mount at my home and a mount at his will be in alignment regardless of the difference in alignment of the tops of the piers.

James

52 minutes ago, Swoop1 said:

One question. I initially levelled the adapter plate but then had to make adjustments so that the HEQ5Pro integral spirit level was spot on. Are these levels accurate enough?

It really doesn't matter.  By polar aligning you'll take all of that out of the equation.  Having the pier adapter level may make it simpler to polar align, but once you're aligned, you're aligned, and whatever state anything below the RA axis is in really isn't important.

I actually considered deliberately making the tops of my piers at an angle of twenty-ish degrees to the horizontal so that the alt adjustment on the mounts could be nearer the middle of its range and less prone to bendy-bolt syndrome.

James

2 minutes ago, davew said:

Surely you mean Milk Chocolate Bounties are disgusting ?? Plain chocolate Bounties are sublime.

I'll take either.  I really don't have a sweet tooth and I'm not particularly into chocolate, but for some reason I do enjoy a Bounty.  Certainly the plain chocolate variety is better, I'll grant you that.

James