badhex

I'll be there today - wearing a bright green hoody and moon trainers, if anyone wants to say hello!

I'm going today for a bit. Any other London folks there? Matthew @DirkSteele are you going? What about @markse68? Shame we don't have any SGL merch to wear so we can identify fellow SGLers! I'll be wearing a bright green hoody and moon trainers, if anyone wants to say hello!

@Michael Kieth Adams @Bugdozer On the subject of orbits being cleared and other specific IAU criteria for definition of a planet, there was an excellent thread last year which might be of interest:

... but in all seriousness, a tough choice but I'm glad you're seeing the positives, as wiser folks than me have already said.

Wouldn't it be the Dave descriptions act?

Does the dog also wear pink crocs?

I literally just used the original paper for the oh-my-god particle as a source in the UCLan Cosmology assignment I submitted last week, so I was reading this very article (the phys.org one) as additional information. The thing I found particularly interesting which is not totally clear is that the GZK cutoff is actually more complicated. GZK also suggests a distance which is think is about 160 mil ly. As I understand it, when a UHECR proton detected on earth has energy above the GZK cutoff, it actually shouldn't be possible for it to have come from a source outside the GZK horizon. A proton with that much energy travelling through the interstellar medium will collide with a photon from the CMB and create a Delta+ particle, which is unstable and then quickly decays back into either a proton or neutron, plus pion radiation of the appropriate charge. This takes about 20% of the energy of the original proton, and will happen multiple time over the distances involved, slowing it down significantly, thus anything detected on earth with that much energy must have come from within the GZK horizon. The big problem is that nothing we know of exists within that horizon which can accelerate particles to those high energies. It's obviously more complicated than that and I don't pretend to understand all of the background, but I thought that bit was fascinating.

I'm visiting my future house location this weekend and the current skies here are dark, clear and still as anything. Orion looked stunning naked eye as did Jupiter and the moon just hanging out together.Obviously I don't have a scope with me! 😭

The EvoLux 62 does look interesting, I was watching keenly when it first came out for new owners' first impressions - I may have even encouraged some brave souls to get one for the good of SGL 😂 I would be interested to know opinions from owners who've now had them for a while. The only thing I wasn't sure about with the EvoLux 62 was the size; though it is still small, from pictures it looks almost like the tube is big enough to accommodate a 70mm objective (the bezel on that OL is huge!), so I wonder if you're saving that much space and weight vs what you're losing in aperture?

I have the solution to your woes - save money on counselling and buy a small APO 😂 Sadly no amount of counselling can save @JeremyS though 😜

I honestly don't understand what it's for. I dearly love the scope but why is it there? Also I'm pretty sure it's not even accurate.

I've heard that's what happens when you lick all the coatings off the objective 👀 @JeremyS

Clearly I'm not going to argue with this 🙃 The fit and finish is very good on the ZS73 and as mentioned the optics are great, but WO stuff is a bit more on the expensive side when compared with some more recent offerings from other vendors which are pretty identical in features, optics etc if not in specific components. You get a case and a few bits like the handle etc, which is worth a few bob. My biggest complaint is that the temperature gauge thing on the focuser is totally pointless 😂

I would say yes, for things like planetary, doubles, PNs etc with the obvious caveat that you can't beat the physics so image scale will always be small, but with better colour correction and sharpness, and overall better build quality, focuser etc. As mentioned I've had no issues with CA in the ZS73. At higher powers, you won't have to worry much about the sky contrast, and from my experience a small, well built APO or ED doublet can take the magnification well. I must also caveat that I do not have an ST80 with which to compare, though I do have a Celestron Travelscope 70, Synta made, which has surprisingly good optics - they are apparently very hit and miss but I seem to have been lucky. The ZS73 is objectively better by any criterion you wish to examine, except of course price.

This is a very good point - and will add my own experience as well. Under none-ideal skies there's no getting away from the grey sky at large exit pupils. My home locations have been Bortle 7 or 8 for the whole time I've had the scope and I definitely prefer to use it in darker skies. Having said that, many of my trips away have not been specifically for astronomy, so on average have had a lot of Bortle 4 and 5 skies, and still thoroughly enjoyed it. Of course, it's all personal preference, but as @josefk says its something you should definitely take into consideration.

Another vote here for 72mm-ish. I have a William Optics Zenithstar 73 (ED doublet, FPL-53) and it's an incredible little scope. I take it abroad with me regularly and everything fits easily into one cabin sized backpack with the tripod on the side - one year we even went island hopping in Greece and stayed on a volcano in the sea with Bortle 2 skies. This is an older photo with an AZ-GTi but I normally take my Scopetech Mount Zero. There is also room for a 2" diagonal and EPs - 6° TFOV is easy in a scope like this. I also managed to squeeze a 2" Herschel wedge in there on one holiday. This photo is from last summer in Italy, searching for Enceladus - which was probably a tall order for a scope this small but not by much! Tethys was no problem which gives you an idea of performance, though for planetary the image scale will always be small (even if it is super sharp). I've also seen the entire veil with an Oiii filter (under good conditions) and many other faint targets which you might not expect for scope so small. It is not quite the all rounder you'd get with a 4" but I've had zero issues with CA even when pushing above sensible magnifications, and in my experience the portability definitely makes up for the loss of aperture. I wouldn't feel comfortable taking my 4" away, but this is pretty easy. It's a heavy backpack once full, of course - about 10kg - but I'm not shy with the hefty EPs, 2" diagonal etc, so you could easily shave weight off.

Seems like you've got a handle on AI art @JeremyS

Silly question maybe, but building on that would using an eyepiece puffer (which has been out in the cold) also work? It would be pulling in, and puffing out, cold air which should help clear the condensation similar to your method? I have in more recent times tried to stick to John's method, and I also cobbled together a makeshift heated EP case using a heater band for during observing as I don't like keeping them in my pocket. I've barely observed since this first few nights I used it so haven't had chance to perfect it:

Same! At this rate I don't think I'll get any observing in before we move house again!

@F15Rules Did you ever get to the bottom of what this was, or try it in your long FL scopes Dave? Also @Louis D in case it wasn't obvious, that genuinely is a copper Yorkshire / solder ring fitting I used to contain the body of a modified webcam. This photo is from over ten years ago - I wonder if the tarnish has got worse since then? 😅

Hi mate, I'm really sad to hear you have been struggling and in discomfort when doing something you love, it must have been a really hard decision to make. That said, I think you're making the right decision on two fronts; firstly I think it makes sense, at least in the short term, to keep your gear for at least a while to see how things pan out. Secondly, welcome back to the light side of the Force! (fun fact: the light side is never mentioned by name until the most recent trilogy, only as "the good side" or just the Force). As you know I've always been a visual astronomer and I look forward to many more discussions with you in the visual forums! 🙂

Also yes - this! On more than one occasion I've found something interesting in the FOV whilst star hopping which I wasn't aiming for but was interesting enough to look up. This is one big benefit of using the whole scope as the 'finder'; the extra light grasp does mean you see more stuff than you would in a finder alone.

I use similar methods to quite a few other on this thread. I don't currently use any motorised mounts, though I have done before. For quite a lot of the time I've actually relied mostly on a very low power EP essentially acting as a finder (Lacerta 40mm ED) when used with my two most used scopes, an F5.9 ZS73, and an F7 Starfield (well, the TS-Optics equivalent). This provides a pretty large TFOV in either scope, around 6° and 3.6° respectively. I have also set up Stellarium with the correct FOV overlays for the EP/scope combos above. I did purchase a RACI not so long ago but it's a bit of a faff to set up every time and too bulky to take away on holiday so I haven't fully got into the swing of it. After checking out the location on Stellarium (with Twilight app running to provide a red screen overlay), I'll find a sensibly close by bright star from a known constellation or asterism. In some cases this might be a star that forms part of a line between other stars and the target, for example. With the 40mm in, I eyeball my bright star and point the scope roughly in the right direction, and most of the time I'm close enough that the star is in the FOV. A red dot finder does help with this and I've started using one more, but sometimes the low angle isn't ideal, plus it's simply not always possible in skies with strong LP. Once I've found it, I'll check Stellarium again to see which direction I need to move in, and what I should be seeing in the EP - for example if my starting star is at one edge of the FOV, what should I see at the other edge, in the direction of the target? I'm quite good at discerning patterns and reversing them in my head e.g. "at the edge of the FOV there are three stars in an elongated triangle shape" so I'll move to those and place them at the edge of the FOV, and again repeat. I usually don't have to do this more than three or four times before arriving at my target and often fewer than that, and then it's just a case of switching up EPs to my desired FL.

A few bits and bobs from family along with this which had been on my list for a while: