Goto Dob on angled surface?

[absolut (Rob)]

Hi,

Apologies if this has already been covered - my searches haven't met with an success...

I have an Orion Goto Dob and I'll be heading to a site (friend's backyard) that I know has a decent angle to it. What is the best thinking for levelling out the dob for viewing/goto operation, or isn't it necessary?

I'd estimate the yard is around 10-20deg incline, might be a little more (been a few months since I've seen it...

Thanks!
Rob

[asimov (John)]

I dare say it will move on you on 1 axis, on a slope like that. I'd just be finding some assorted blocks of wood or something similar to chock the base until it was level; by using a spirit level..

[Damienandwendy (Damien)]

I have been thinking about this lately as well since my new SW 10" Goto Dob arrived today

The concrete pad out the back I use to observe from has less than a 5 degree slope but will be enough to upset accurate goto's I guess. I was looking to manufacture a solution and found these:
http://www.opticsmart.com/accessorie...elescopes.html

At the best part of $100 delivered, I think I will still try to make something myself, but it is something to go off. Edit: Doesn't look like they deliver to Oz anyway but it still is a nice idea

cheers

[absolut (Rob)]

Yeah Damien,
I was thinking of getting some adjustable feet, but I don't think they will be enough on this slope, not sure about stability.

I'm not much of a hardware person or I'd try and make some kind of expandable wedge-thing the dob could sit on and be level...

The search continues...

[Allan]

G'day Rob,

Good to see you picked up a nice telescope. IIS AstroCamp will be even better for us both next year.

In my travels I read something about firmware V3.XX, which you will have in your SynScan controller, compensating for slope during the 2 star alignment. Having said that, I cut up some fibre cement sheets of various thickness and I use them to level my scope with a small spirit level when I set up. As mentioned, some timber or bricks would be the go for a serious slope.

[glend (Glen)]

I built a three point leveling base for my GSO 12" Dob and it works just fine in my sloped backyard (which is about 10 degrees). I use small squares of ply to prevent the screw down feet from sinking into the yard, and on the slopng concrete driveway its fine on it's own ( but it has rubber feet on the screw down legs). You can buy wooden door wedges at Bunnings and they look like they could do 20 degrees and have rubber on the bottom. You might need a ground board staked into the ground to keep it all from moving. You could also take a shovel and 'create' a level spot in the yard, I do this all the time with my campertrailer.

[Wavytone]

Whether its level only matters from a mechanical perspective, in order to have uniform loads on the motors and the ensuring the way the mount flexes is uniform in all azimuth directions.

With respect to the mathematics of what it is doing, it doesn't matter at all if your mount is tilted - remember the earth is round - so a tilt is merely equivalent to using the scope at some other latitude and longitude (the shift is equivalent to the tilt). The software will deal with this automatically.

[IanT]

Does that mean that if I align my dob to North South on a hill slope which is the same angle as my latitude - that I will have the earth itself as my equatorial mount?

[jjjnettie (Jeanette)]

Originally Posted by IanT

Does that mean that if I align my dob to North South on a hill slope which is the same angle as my latitude - that I will have the earth itself as my equatorial mount?

ha ha.

I suggest buying 4 pavers and digging them in to make a level surface.

[Barrykgerdes]

Technically you do not need the base leveled to do a two star alignment. However this may be impractical if the slope is too much as it will cause instability.

It is also highly improbable that the slope would be correct for a polar alignment even if the rocker base was suitably modified.

The best way to make a Go to Dob. perform satisfactorily is to get the base level and if there is any scale on the base set it so that 0 degrees points towards the north. In fact if you accurately level the base and enter the date/time and location accurately a one star alignment will be all you need to find most objects.

Barry

[absolut (Rob)]

Thanks for the feed back!!

Sounds like I'll make use of some camp stakes and some timber/bricks.

Yes Allan, looking forward to the next camp (Bretti) and IISAC2014!!

My gear is already a decent improvement - not the huge step up you've done though!! I'd like to have bought the 12" version, but the tube is too long for my car, the 10" will do the job well enough!!
I'm still upgrading/adding to my kit... going to be a bigger challenge getting all of this in my car though... lol... just bought an 80W folding solar panel for battery charging and what not...

Clear skies (and wallets!!)...
Rob

[Allan]

I remember how much trouble you had fitting your refractor in your car to go to IISAC. We will have to compare XTg upgrades at Bretti