BIG dob ready for first light

[mdstuart]

Good evening

Here is my new dob ready for first light.

I understand it was made by Darkstar as a prototype. It has a 20 inch Jim Hyson mirror in it.

So a little star test tonight with a first object of M13 as the previous owner loves Globular clusters.

Mark the galaxy hunter..

 

[John]

Glad you got a 20 in the end Mark

I'm sure the views of M13 etc will be wonderful - it's pretty cool in my 12 !

 

[westmarch]

Looks great Mark.  What sort of component weight are we talking about?  

I would be interested in your view on the additional detail visible in M13 over your 16”.

John

[Paul73]

You’ll be hoovering them up with that baby! I’m starting to get aperture fever.

Looking forward to the reports.

Paul

[Stu]

Have fun with it Mark, sure your galaxy adventures will continue very nicely now! All these lovely big new scopes showing up! Must get my 12" sorted soon.

[antariksha]

Mark, best wishes. It is an exciting time for you. The DSOs will be outstanding.

[Paz]

That looks great, good luck with first light!

[FenlandPaul]

Superb, Mark - really looking forward to reading of your adventures. Apart from 20”, what do you know of the specs?

Paul

[mdstuart]

First light report

I had an enjoyable time getting used to the scope last night. Collimation was done by some unique poles that allowed collimation from above the mirror. An excellent feature!  I managed to get good collimation and then proceeded.

The scope balances well and moves well without any need for brakes. The focuser is a standard Meade single speed but works well.

I had some fine views of M13 the globular with stars to the core. M3 was also splendid. I also looked at the ring nebula, the dumbbell and of course a few galaxies including M51 and M81/2. At this time of year it was not astro dark and the skies were a bit milky but I was down to mag 13.5 fairly easily so it will be interesting to see how deep the scope will go when it is really dark.

I did a star test. One side of focus was lovely with even circular lines. On the other side it was a bit more fuzzy with some whiskers I think they are called. I think the fuzziness is normal as a big scope cools down and the whiskers may be due to tube currents. Time will tell. Close to focus a little bit of mild astigmatism was present but no worse than my current scope and this did not impact the views noted above so will not impact my enjoyment of this lovely scope. I will probably get the main mirror re-coated next summer and I may look at re-mounting the mirror then on some silicon like I did with my old 14 inch or get a new mirror cell. 

I was just able to take down the telescope unaided but I plan to get some wheels to move it in and out of the shed. I am creating an insulated box to house it in the shed to reduce the chance of condensation with temperature difference during the daily cycle.

Over time I hope to build a new top hat and base to replace the current heavy but useable ones.  

I am going to really enjoy this scope and my journey with it.

Mark

[mdstuart]

7 hours ago, FenlandPaul said:

Superb, Mark - really looking forward to reading of your adventures. Apart from 20”, what do you know of the specs?

Paul

F3.9 I think so I need a small stepladder to get to the eyepiece at the moment. If I can make a smaller base then maybe I might get to the eyepiece from the ground!

Mark

[estwing]

Super scope Mark looking forward to hunting along with you. Clear skies!

[jetstream]

18 minutes ago, mdstuart said:

I am going to really enjoy this scope and my journey with it.

Great first light Mark and I await your reports!

[mdstuart]

Out again tonight. Some amazing views including the wild duck cluster. Interestingly the views were perfect with no astigmatism at all below 45 Deg alt. So the mirror is excellent and the slight astigmatism must be collimation or mounting related.

I had a look at M51 and even though we are not in full astro darkness I can see the outline of the main spiral arms.

I am enjoying getting to know the scope. It's already like a new friend!

Mark

[barkis]

How I envy the Big Dob Squad, but in a nice way of course.
I had the pleasure of using a 20" Obsession a number of years ago at a Kelling
Star Party. The targets I managed to see before giving way to a queue of folks also waiting
were M13, M27 and the Veil Nebula. I was astounded by the unbelievable  views  in the eyepiece.
You're in for many many glorious sights in yours Mark.
Enjoy to the full.

Ron.

[Piero]

Nice one, Mark! Congratulations on your new dobson which I'm sure will provide you with a lot of new targets to observe.

Maybe the slightly astigmatism you spotted the first time was due to the telescope not fully cooled? It happened with my new dobson too, and once it was cooled down, astigmatism was gone completely.

[niallk]

Big congrats Mark!!  Will be looking forward to more galaxy hunting reports!  Sounds like an interesting scheme for collimating - is it a bit like what ES have done on their truss dobs?

Enjoy that massive 20" of aperture

-Niall

[John]

Great early big aperture reports Mark !

The sky last night was excellent even with my little 100mm refractor with the Veil and Owl nebulae being just 2 of my targets. Must have been fun with 5x the aperture to play with !

 

[mdstuart]

How do you get a big dob out in the evening on your own?

Four monster quick release castors!

[John]

Where do you keep it Mark ?

[mdstuart]

I am building an insulated box for the shed. This will minimise the chance of condensation each morning as the shed warms. To be fair the mirror seems to stay dry anyway within its box and with the box covered with a quilt😀 

[Trikeflyer]

Great to see you got what you wanted. Enjoy the views and the other projects when it’s cloudy!

cant wait to hear more!

steve 

[mapstar]

When I first saw the new scope Mark I instantly recognised the dark star colour.

Sounds like the views are living up to expectations. I have a 14" mirror made by the same guy waiting for me to build the shell for it.

Will keep an eye out for your reports 😉

[Mark at Beaufort]

Hello Mark sorry I have been away and only just picked your thread.

Really pleased you obtained the 20" Dob in the end. You certainly have moved on from your 10" to 16" and now the big 20".

As you say the darker nights are really going to show its worth. So many more DSOs - is there any particulars objects/groups that you plan to observe?

 

[mdstuart]

Thanks everyone for your interest in my new dob. I will certainly be posting reports on here but I have not selected any specific targets yet.

I am looking forward to many enjoyable sessions once the dark skies return. 

I plan to put the wheels on today, transfer my finderscope across from the 16 inch and tidy up the box elements with some wood filler etc.

I am also trying to source distilled water to give the mirror a light clean...

Mark

[mdstuart]

What is that! A spanner to secure a bolt 😀