John

15 hours ago, neil phillips said:

Another interesting experiment might be to image the moons, with different size scopes, and see the effect resolving them.  I could do it. i have a 102. 120. 127mm refractors here to attempt it. Not sure if i will try. but a interesting idea. They say the camera never lies ? 

That's a good idea.

I have a similar range of refractors so could do a similar comparison sometime.

When I was trying out the Vixen SLV's for the forum (I tried the 20mm, 12mm and 6mm) I really liked them.

The 6mm in particular was a very good high power eyepiece. I compared it to the Baader Genuine Ortho of that focal length a number of times on Saturn and Jupiter and could see no performance difference between the two. The SLV was a more comfortable eyepiece to use though with it's long eye relief and large eye lens.

I seem to be able to happily adapt to having slow motions (ie: my Skytee II and T-Rex) or not (ie: my 12 inch dob and Giro Ercole). I sometimes find them very useful but if they are not there, I'll do the job myself

If slow motions are fitted then they must not judder, create additional vibrations or have more than a very small amount of backlash. Achieving the latter can be a challenge on the Skytee II but I've managed it after quite a bit of tweaking.

The T-Rex slow motions are superb

25 minutes ago, Pixies said:

My first telescope was very similar to this: 

I spent more time spying on the neighbours (innocently I might add) than astronomical observing with it!

I've been tempted to get one of those (or something like it) to try and replicate (to some extent) the views that Galileo might have had from his scopes.

I can't see his neighbours house from here though, so perhaps it would be a waste of time

As I said in my post much earlier in this thread, it was Neil Armstrong and Buzz Aldrin walking down those steps to the lunar surface in 1969 that got me hooked on all things space related (I was 9 years old) and that led on to joining the school astronomy club a couple of years later. I didn't have a scope of my own for a few years after that but managed to borrow a couple from friends from time to time - 60mm Tasco refractors of course, which were about all that ordinary folks could afford back then 

I'm still not entirely sure if this hobby is really for me though - I'll give it another couple of decades and see if I really get hooked

When I've owned SCT's and mak-cassegrains in the past I've just used a dew shield rather than a heated dew band. My usual observing site is not that affected by dew usually though so the requirement might be "location dependant"

When I used to take scopes to the SGL star parties which are on a riverside site, dew was much more of an issue and I seemed to need all the dew busting apparatus that I could get !

Great report Magnus

At the risk of leading you and your 12 inch further astray, NGC 404, the "Mirach's Ghost" is a small galaxy close to it's namesake star and well worth a look when in that part of the sky and also you should look out for NGC  604, a small patch of light near a star right next door to Messier 33 - it's significance is that it is an HII star forming nebula within the Triangulum Galaxy, probably the easiest DSO "in another galaxy" to see

What a great mount / tripod !!!

I had a demo of one at the International Astronomy Show a couple of years ago and it was very, very impressive

Do stars in the centre of the view look like this or is it just those towards the edges ?

3 hours ago, JeremyS said:

 

....Good there was no sign of The Hound 🤣

Well, we did take this rather old and corny DVD with us and watched it on one of the cloudy nights

Quite fun with a bottle of decent red to calm the nerves !

2 hours ago, Stu1smartcookie said:

Hi John .. a revelation 12” which is basically a GSO …I’ve uploaded a picture of the layout .. a fairly standard one .. I changed the screws back to the original but will be changing them back to bobs knobs shortly . I am certainly going to follow Ed’s suggestion about the clip screws . I like the idea of not “sticking “ the  cork pads to the mirror although if it helps keep the mirror from movement then I will fix it . 

It looks the same as my old Meade Lightbridge 12 inch.

The stock primary collimation springs needed upgrading on that and I found that the thin metal used for the cell construction flexed when the locking screws were tightened so I didn't use those.

I replaced the collimation and locking screws on mine which also helped in adjustment accuracy although the latter still caused cell flex if used.

I have to say that my simple Orion Optics cell (pictured in my last post) has proved a better one than the GSO type.

Before clouds spoiled things I was observing Jupiter last night with my 4 inch Vixen ED refractor.

At 166x magnification Jupiter showed a nice large, if slightly flattened, disk. It's apparent diameter last night was a generous 48.2 arc seconds. 

The four Galilean moons (Io, Ganymede, Europa and Callisto) were strung out nicely in a line to one side of the planet. Observing them carefully at the same magnification showed each as a tiny but clear apparent disk.

Each time I observe these moons at a reasonable level of magnification I can see a noticeable difference in the size of their disks. Last night, as on other occasions, I tried to work out which moon was which simply by noting the relative apparent diameters of their disks, sketching their positions and my "predictions" of which moon is which and then checking using Stellarium or Cartes du Ciel software to see the actual respective positions of the moons.

Last night I got 2 out of 4 right, confusing Callisto and Io but finding Ganymede (the largest) and Europa (the smallest) clearly to show their identities through their apparent size in the eyepiece.

What interested me last night was why and how we, as observers with modest telescopes, can actually do this

I don't claim to be an exceptional observer and I have read reports from others quite often who spot these apparent size differences between Jupiter's major moons.

Last night the actual angular sizes and brightness of the Galilean moons, according to Stellarium, were as follows:

Ganymede = 01.78 arc seconds / magnitude 4.6

Callisto = 01.62 arc seconds / magnitude 5.8

Io = 01.23 arc seconds / magnitude 5.4

Europa = 01.05 arc seconds / magnitude 5.3

To put these in perspective, the maximum resolution of a 4 inch aperture scope is around 1.14 arc seconds I believe so all of these moons are far too small to really be resolved in such a scope. 

So why do we see differences in the apparent size of the moons with comparatively modest aperture scopes ?. Why is it quite obvious, with a little observation, which moon is Ganymede ?. Why does the somewhat smaller Europa appear just as that through the eyepiece ?

My guess is that we are seeing a form of optical effect rather like the airy disk produced by a star but produced by a combination of the moons brightness, it's comparative apparent diameter at the time of observing and the aperture of the scope rather than the "true" disk of the moons.

I'm not 100% sure of this at all though so would be very interested to hear other views   

20 minutes ago, Captain Magenta said:

… though that must come at a cost? How were the sleep/tiredness levels John?

Not really a problem. I did not actually stay out too late each night - maybe until midnight ?

Being on holiday we were not getting up too early each morning either.

18 minutes ago, Stu said:

I had a look for the first time I. Ages tonight with my 10x50 Greenkat binos. It looked the same as HD220057 to me, so I would say mag 6.9 tonight. It was nice to be able to clear see M52 in the binoculars, it was barely visible in a scope from my old house!

@John am I missing something? M57 cluster? That’s a new one on me, so I’m a bit confused?

I thought Messier 57 had more of a "ring" to it !!!! 🤣

More likely lingering effects of the excellent Dartmoor Brewery products though

Have we really been observing this nova for nearly 6 months ?!!! 

Nice view tonight with my ED102SS refractor at 28x. Nova looks to be  magnitude 7.0 I reckon. Excellent view of the Messier 57 cluster AKA "Salt and Pepper", apparently, although Messier 37 also seems to have been dubbed that. M57 shows as a delicate fan shaped spray of resolved stars. Very nice.

Edit: Messier 57 ???? - nope, it's Messier 52 of course !!!. Doh !!!

My little Vixen ED102SS F/6.5 is trying to see Saturn through some cloud cover tonight - ever the optimist !

I've forgotten what scope you have Stu ?

My 12 inch Orion Optics has the older 3-point primary cell with fairly simple mirror clips and lateral nylon screws to hold the mirror central. I keep the clips slightly off the mirror surface and the 3 nylon screws gently touching the mirror to keep it's optical axis central. The mirror is resting on nylon pads but is not stuck to the cell.

I don't use the locking screws unless taking the scope for a journey because they do impact the collimation.

Other than that, mine holds collimation pretty well.

Collimation is key to resolving things, globular clusters included.

6 minutes ago, jetstream said:

👍

Yes! wherever Dartmoor is lol!

 

Our most southerly National Park:

In the county of Devonshire (where I was born as it happens).

950 square km of granite uplands with deep wooded valleys.

These are really great scopes

According to Markus Ludes at APM, demand and sales of the 130mm F/6 LZOS are around 4x-5x higher than for the F/9.2. That's unsurprising really given that the F/6 is so much more suitable for imaging as well as more of an "all rounder" for observing.

As of this time last year, Markus said that the total production of F/9.2's would be likely to top out at around 130 units. The highest serial number that I've seen for sale to date is #123.

9 hours ago, ONIKKINEN said:

.... the dim light from my digital watch was a serious source of light...

 

When I see discussion of using tablets / mobile phones while observing in the field I think of this. I've had just the same experience with a digital watch illuminator under a really dark sky - and that was on the other side of the field that I was observing in !

Until you have observed under really dark conditions and managed to get fully dark adapted, it is difficult to conceive how even dim lights can negatively impact the experience. But they really can.

4 hours ago, Roy Challen said:

Although I love my solar and planetary, this is still my Number One astro experience. Ever.

It was one of my very best as well, in 40+ years in the hobby

Next time we go there though, I will be very tempted to take a small wide angle scope as well

How heavy are the 130 F/6's ?

My F/9.2 weighs 9.4kg including tube rings / finder / diagonal and Losmandy DT bar.

I think the optical reports with the LZOS refractors are to demonstrate that the objective meets or exceeds APM's lens spec. Or at least that's what Markus at APM told me. In practice they tend to independantly test a little better I think. It's not just the raw strehl, RMS and PV figures. The lens surfaces are hand finished and matched to each other on an objective by objective basis and then fitted into a precision cell where the contact points and spacing are precisely aligned, again by hand. So each objective is an individual work, as it were.

It's what you would expect for their cost of course. The LZOS objectives on their own in LZOS cells are fearsomely expensive:

https://www.teleskop-express.de/shop/product_info.php/language/en/info/p11283_APM---LZOS-130-mm-f-6-Triplet-Apo-Objektiv-in-Zelle.html

Here is the APM minimum spec for the objectives:

APMApo-Linsen-Spezifikationen.pdf

That is a superb pair of scopes @Stu. Unless aperture fever strikes, they should set you up for a lifetime's observing

And I'm sure you have a couple of other quality "lightweights" for travel / grab and go observing as well

Keeping away from the NV debate .......

14 minutes ago, Deadlake said:

How does altitude (above sea level) affect seeing, imagine it helps????

I think it helps but we were not that high up - maybe 350 metres ?

I think what made the skies dark were very few man-made light sources in the a sparsely inhabited valley and the surrounding hills shielding any light domes from nearby towns (the nearest was 8 miles away).

I've taken a 6 inch scope to a dark sky and had similar deep sky performance to a 10 inch at home. My back yard is not too bad as long as you avoid the horizons to the SW and NE where large cities lurk. I've seen the Horsehead Nebula with my 12 inch dob a couple of times which I feel is a reasonable achievement from a garden in the edge of a large town.

It was lovely to get under a really dark sky for a while though