westmarch

4 hours ago, John said:

I've done a few outreach sessions with scouts, cubs, guides etc though Bristol AS.

My tips would be:

- plenty of parent helpers to supervise small groups (3-4 children per helper)

- each scope has a dedicated operator who knows the instrument

- assign each scope operator 2-3 easy targets that will be seen well with that instrument and that the operator is comfortable with finding quickly and easily.

- have a reserve list of targets in case of patchy cloud cover getting in the way of original targets !

- an event leader to give an initial briefing and intro to the main constellations

- be quite clear about the rules: no running about in the dark, no touching scopes etc etc. Dark and being somewhere different can lead to over-excited children !

- divide the children up and then let each small group go to a scope for about 10-15 minutes

- move the groups around the scopes, on a signal from the leader - a whistle maybe ?

- attention span on a cold night is quite short so let them all see something, then a quick chat, then move on to the next scope.

- do you have a loo nearby ?. Adding a portaloo to our site makes a lot of difference to the comfort of guests and supervisors !

- don't be too ambitious with the targets, length of briefings etc, etc. Keep it simple !

Have fun

 

Having done this with cubs, fully support all that John says.  I found that a crescent moon is an easy target and one that is appreciated by most, if the planets are visible then Jupiter and Saturn take some beating.

John

Many dob users have a red dot finder, mounted beside the RACI, to get in the approximate vicinity and then switch to the RACI finder. HTH

John

I almost always travel to a dark sky site 20mins away.  There is just too much light pollution, heat emitting roofs and other obstructions where I live to see any worthwhile DSOs.

I can check a weather forecast, pack my kit into my car and be set up within 15mins of arriving. 

John

Hi there,

Having used the websites you mentioned I have visited the more westerly of the N York Moors. The N York Moors dark sky site at Sutton Bank has been blighted by an adjoining horse racing stud farm that has horizontal halogen spotlights to deter horse thieves. 

There is a lay-by at the White Horse Glider Club that has an unobstructed vista and the spotlight from the club house to the North can be obscured by your parked car.

There is low altitude light pollution from York to the South and Thirsk to the West    .

It’s down as Bortle 4 but is my favourite nearby site that offers a decent view of the Milky Way.

NB Sutton Bank is a very steep hill - bear that in mind - a winter descent in the wee small hours,  before the gritters have been out,  is not for the faint hearted.

John

22 hours ago, NGC 1502 said:

 

Maybe I’m getting lazy but for me convenience trumps hassle. As is often said, your mileage may vary 😁

Ed.

I agree, In the end the best scope is the one you get out most. 😉

John

1 hour ago, Piero said:

To me a solid tube makes sense up to 8" - 10" with f.l. of 1200mm. These sizes fit the back seat of a car. With a focal length longer than 1200mm, I don't see any advantage in using solid tubes, whereas I do see many advantages in a truss design.

I am aware that this comment will be confronted, given the fact that here in the UK people seem to prefer solid tubes no matter what.

I wonder whether this preference is primarily due to the design of the UK Orion optics VX solid tube dobson, and people willing to stick to UK brand / choice.

I too am a truss dob fan,  mainly for the portability, rapid cool down and ease of getting it to a dark sky site.    I have to say that the loss of collimation issues do get a bit overblown with truss dobs. I’ve found that collimation holds well and is quick to adjust as part of any routine set up.

I can however see the advantages of the simpler, solid tube design such as cost and if you don’t plan to transport it.

John

On 11/08/2021 at 04:51, Atomic__Bear said:

John,

I got an Orion XT8i dob for my birthday a couple months ago (my first scope ever) and I'm super impressed.  The only thing it's lacking (for now) is an EQ Platform, so I started researching and found TONS of useful information in a LOT of different places!  I read through your guide (stellar DIY instructions, bro - good job!) and I'm leaning toward making a VNS platform like yours (or very similar).  I'm curious about the pivot "bearing" for the South side... All the other VNS style EQP's I've seen so far have a radiused / latitude-angled south bearing, except for Reiner Vogel's.  Do you still recommend using a pivot-type South Bearing, or looking back, would you change to a radiused / angled one?  I'm about to start gathering the parts and start fabrication, but I thought I'd ask first.  Again, awesome build, and I'm looking forward to this project more than I have on any other one in many years!  Cheers,  Chris in Vancouver Canada.  (49° N. Lat if that helps for your answer - I know from reading a bunch that the pivot mount likes to be used in further north latitudes, but I'm not sure if 49° is far enough)  Thanks and CLEAR SKIES!

Hi Chris,

Reiner has put up VNS segments for 48 and 50 degree platforms without specifying an alternative arrangement for the South bearing. I would go with the master’s judgement. 😀

Good luck with the build.

John

7 minutes ago, Alan White said:

The joy of the look out from Earth upon the Cosmos in the company of the Badgers, Foxes, Norah the Bat and others,
and the simplicity of it without too much hassle is the tonic I need.

you forgot Mossie and Midge but by one of life’s amazing coincidences they are only around when true darkness isn’t .😀

John

I am purely visual, I love the experience of being alone at a dark site with the universe spread out above me.

As hobbies go, photography has always been one of the most popular ones - explaining why everyone has a high tech camera in their pocket.  Photographers are seeking new and more complex challenges like AP.  I suspect that as tech simplifies the AP process, something else will turn up - 3D photography perhaps? 

John

Hi there,

enjoyed your report and early morning enthusiasm.  Welcome to the forum.

John

Hi there,

welcome to the forum from God’s own county.

John

3 hours ago, paulastro said:

Where are you John, I'm in W Yorks and we have some sun at the moment - S and E Yorks have better conditions forecast.  

Hi Paul,

got a break in the clouds just after 11:00. Hope it clears up for you. 😎

John

75% Cloud cover in Yorkshire with prediction of 100%!!

John

There is a Meade ETX 90 on ebay at present with an Autostar controller at £41.

https://www.ebay.co.uk/itm/203447649649?hash=item2f5e6cc571:g:c1cAAOSwZ~pgmTrV

Worth a look.

John

After a day of torrential rain and hail the forecast was for clear skies. I sceptically took the grab and go ETX 90 out to a low NW horizon and it was a completely clear sky......... except for the NW horizon line of cloud.   I could see Venus but then even that was occluded by this line of cloud. I despaired of these moving but at 21:50, they shifted and there it was!! I managed to to see the half illuminated phase by using a 15mm BST Starguider  at x85 mag.

Thanks to all on this thread, for your posts and encouragement.  That is only the second time I have managed to see Mercury

John

Hi Adam,

as someone looking up in Yorkshire, I would give you this advice, more as a reference than a guide for tonight:

Tonight is good - look up and identify the different constellations by getting a good and free star guide: Stellarium for PCs, Sky Safari for mobiles or download a free sky chart e.g. :       http://skymaps.com/downloads.html.  Aside from the Moon and planets, I find that Caldwell objects are hard to beat - the  Northern Hemisphere objects tend to be the easiest and most rewarding things to see from UK: https://in-the-sky.org/data/catalogue.php?cat=Caldwell&const=1

Second: Check out the weather forecast - lack of cloud is key here - no sense in getting your gear out and its cloudy.  Plug your postcode into this:  http://clearoutside.com/forecast/50.7/-3.52

Third: try to look up - as far up from the horizon as possible - less light pollution and it means you are looking through less turbulent and hazy air.

Fourth: Ideally get away from surrounding lights - turn off nearby lights, get behind shade or, ideally, go to somewhere dark - seeing most astronomical things is about contrast between dark sky and lighter object. The darker the sky the better and this is worth more than many expensive filters and will often double the number of faint objects you can see.  Light pollution means you end up trying to distinguish  between  different shades of grey. This map shows you nearby darker areas https://www.lightpollutionmap.info/#zoom=8.27&lat=53.7236&lon=-1.1296&layers=B0FFFFFFTFFFFFFFFFF

This map shows you nearby public dark sky sites:  https://gostargazing.co.uk/location-map/

Last: enjoy yourself - exploration is the heart of the hobby.  Finding new things is what makes it enjoyable.

John

2 hours ago, Jiggy 67 said:

I also use SkySafari

It may only be available on the plus and pro versions, I’m not sure, but it may not be available on the basic version.

The log utility is perfect when used with observing lists. I plan for the evening by creating an observers list and make notes/ sketches in a handwritten log book. The following day I update my SkySafari log which has all my equipment preloaded. All objects observed have all their details/info attached. All past observations can be highlighted or not as required and all obs of any particular object are in one place. All this works across the cloud to different devices.

 I even go further and create a spreadsheet from observations lists which SkySafari does automatically and fill them in as I go along.....so my obs are stored in three places.....handwritten log, SkySafari and on my computer.

 

I didn’t realise that the basic version lacked the log, so sorry if I misled.   I upgraded during one of the many half price sales for Sky Safari. Having said that, I have spent a lot more on other astronomy kit that rarely sees the outside of the box.  I use the app and the log every session.

John

I could only aspire to be as methodical as you Rob!  About 5 years ago, I started to use the log on Sky Safari and have found it invaluable since.  I can toggle on and off my sightings on the star chart, its available on my phone and it encourages me to record my observations more consistently.

Its not for everyone but it works for me.

John

Hi Frank,

You are certainly boldly going where nobody, except @Moonshane has gone before.  The short answer to all your questions is that you are going way beyond anything that I would have attempted. Reiner effectively did the work for conventional 8” and 10” dobs.  Given that most of the weight of a dob is the mirror, yours is really heavy.  My advice would be try to PM  @Moonshane for advice. He has been checking in recently so may be able to help.

In answer (guesses really) to your questions:

1. The important point is to have the feet of the dob as close as possible to the outermost edge of your platform and that should be as close as possible to the perimeter of the circular dob base. You are trying here to create as wide a base as possible since when it tilts you do not want the centre of gravity of the dob to go outside the base or it will topple over. That is a very real risk with your setup. You could end up injured and under this is if it falls and at best it could be a very expensive exercise.

2. You are altering the effective length of the VNS ellipse so you will get some target drift.  For visual observing, it probably doesn’t make a lot of difference, particularly if you are using your dob as a light bucket for DSOs with a wide angle, low powered EP.

3.You need to up the size of the bearings and also the thickness of the aluminium arcs to provide better mechanical strength.  Hard to say if the motor can cope - common sense would say it will struggle.  The weight of your rig will certainly give rise to more inertia and friction .

4. Reset - you turn the drive off and slide the arcs back to the start point - it takes some physical effort with a 10” which is why designs for larger dobs have a clutch built in to release the motor and let the arcs run back on the bearings.  When the rig reaches the end of its travel, it hits the bolt stops on the aluminium arcs and starts sliding on the bearing.  You hear the judder but the weight of your rig may mean instead of sliding, it simply burns out the motor.

Sorry Frank if I sound like a wet blanket here but I really think you need better advice than I can give.

John

45 minutes ago, John said:

The base of my 12 inch dob is modeled approximately on the OO base design but carefully made from quality plywood. I suspect it's footprint is a little larger than the OO version would be but not by much. Each time I use the scope I offer a little vote of thanks to @Moonshane who made it for me

While being very smooth in both axis, it also does that other vital thing which is to hold the scope really steady on the chosen target, even at very high magnifications.

I did own an equatorial platform (made professionally in Cornwall) for a while and that worked well with the scope. Eventually I decided that I could manage well without though and loosing those couple of extra inches of eyepiece height was actually an advantage

 

Moonshane inspired so many people who watched his trial and error blog and the huge amount of invaluable links he posted .  THE god of equatorial platforms has to be Reiner Vogel though. Nobody has explained it in so much detail and for free.

http://www.reinervogel.net/index_e.html

John

On 18/04/2021 at 11:38, Jim-Lad said:

Hi John,

Oops - I forgot to hit the submit reply button! 

Many thanks, I'll make sure my template matches your measurements. 

BTW, for the South pivot point I'm going to try substituting an inverted mini-ball head from a camera tripod (£5 approx. on Ebay)  - once it's all up and running I'll post my efforts...

Best regards, Jim 😎

 

Go Jim!  We all learn from each other.

John

What is the transit time on your platform? I used to worry when I had to reset mine thinking it would topple over but it has proven remarkably stable with recesses for the feet of the scope to sit in.  You look as though you have belt and braces with bungees and weights! 👍

John

Where there’s a will there’s a way.  Well done 😀

John

Those who get their mirror out most see more..... regardless of muck. 😉  Enjoy these cloudless nights and (relatively) low jet trail pollution.

John

Hi Jim,

hope the attached  gives you confidence. 

B W

John