Polar alignment "drift" on permanent mounts

[rally]

Fred,

Its Catch 22 !

If you act and remove it then the roots will rot over time and the soil will move !
If dont act it will keep growing and the soil will move !

On the otherhand - it may not be the tree roots themselves but the moisture in the reactive soil of which the tree will have an effect in Summer when it saps the soil of all residual moisture.

In any case I would still install some ag drainage pipe in a large perimeter around the Obs.
Water the ground in Summer.
. . . and dig a 2m deep pier footing - I'm busy that weekend too !

Good luck with it - at least Tpoint makes life easy, just that your 400 point model will have to be redone very frequently.

Cheers

Rally

[Barrykgerdes]

Originally Posted by strongmanmike

Anywhere you can get an up to date SCP map..?

Mike

only if I invent it myself.
I will have a look at Stellarium it should calculate RA/Dec of the date.

I have made a screen dump from Stellarium.The darker/bluer grid is todays. The lighter/greyer grid is the J2000.

Like you said the SCP has moved 3' 32.35" in the direction of 12hr RA in ten years

Baz

[tlgerdes (Trevor)]

Originally Posted by Bassnut

Barry. Well there you go, a slab. 2.4m square?, thats just 1.2 * 1.2m,.

How do you do so well at Astronomy when you obviously failed 6th grade maths.

1.2m*1.2m = 1.44sqm

[Bassnut (Fred)]

yeah yeah it just poped out, a brain snap, sheesh

[Geoff45 (Geoff)]

Originally Posted by strongmanmike

If that is the location for the SCP in year 2000, won't it have precessed about 3.3' since then? If so in which direction would this be in this photo? ie where on that DSS photo is the SCP now in 2010?

Mike

The scope is aligned parallel to the earth's axis and is fixed to the solid ground, so precession does not affect your alignment--the scope moves with the earth as it precesses and always points to the changing scp.
Geoff

[Barrykgerdes]

Originally Posted by tlgerdes

How do you do so well at Astronomy when you obviously failed 6th grade maths.

1.2m*1.2m = 1.44sqm

Gee Trev that's the same answer my calculator gave.

Barry

[multiweb (Marc)]

Originally Posted by Bassnut

Its on top of a cliff, next to a huge excavated hole (the whole street), that was a quarry, but some 35yrs ago, perhaps the ground hasnt settled yet from that activity.

When you leave the obs do you have the door to the right with a big sticker 'DO NOT OPEN - TAKE OTHER EXIT' And I thought Richard Crisp was living dangerously next to his pool. If the coppers see you laying down on the street below with broken bottles of southo around they might get the wrong idea and put you in the paddy wagon

[Bassnut (Fred)]

Originally Posted by multiweb

When you leave the obs do you have the door to the right with a big sticker 'DO NOT OPEN - TAKE OTHER EXIT' And I thought Richard Crisp was living dangerously next to his pool. If the coppers see you laying down on the street below with broken bottles of southo around they might get the wrong idea and put you in the paddy wagon

Well, scambling up and down the cliff in the pitch dark in various wobbly states when Ive forgotten where the torch is gets interesting at times . But if I plan it right, if I trip, Ill end up diving into the pool with no damage, so I dont worry about it .

Ohh, and I quit the Southo a couple of years ago. Beer is much more brain friendly, and a blood test lately showed my liver was back to normal, after being off the scale during the southo years (was fun tho), its scary when you get * as a test result (unreadable) .

[strongmanmike (Michael)]

Originally Posted by Barrykgerdes

only if I invent it myself.
I will have a look at Stellarium it should calculate RA/Dec of the date.

I have made a screen dump from Stellarium.The darker/bluer grid is todays. The lighter/greyer grid is the J2000.

Like you said the SCP has moved 3' 32.35" in the direction of 12hr RA in ten years

Baz

Thanks Barry

A little over 5 years ago I did an accurate drift align with my AP on the Tak NJP and noted the location of the cross hair in my Tak polar finder, I did a drawing of the Polar finder field noting the location of the SCP (polar finder cross hairs) in relation to Hip 71348 and Hip 58752 and it was a nice almost equilateral triangle but as your Stellarium map shows this triangle has now flattened somewhat and this fact will help me better locate the true SCP now, thanks! Interestingly, it appears that by 2035 the SCP will be located nicely in the middle of these two stars which will make polar aligning with a polar scope very easy!

Mike

[strongmanmike (Michael)]

Originally Posted by ghsmith45

The scope is aligned parallel to the earth's axis and is fixed to the solid ground, so precession does not affect your alignment--the scope moves with the earth as it precesses and always points to the changing scp.
Geoff

Yeh I was aware of this Geoff, I was just fishing for a Gerdes SCP location map to help me polar align my NJP mount using its Polar finder scope and as usual Barry delivered! Thanks Barry

Mike

[Barrykgerdes]

Originally Posted by strongmanmike

Thanks Barry

A little over 5 years ago I did an accurate drift align with my AP on the Tak NJP and noted the location of the cross hair in my Tak polar finder, I did a drawing of the Polar finder field noting the location of the SCP (polar finder cross hairs) in relation to Hip 71348 and Hip 58752 and it was a nice almost equilateral triangle but as your Stellarium map shows this triangle has now flattened somewhat and this fact will help me better locate the true SCP now, thanks! Interestingly, it appears that by 2035 the SCP will be located nicely in the middle of these two stars which will make polar aligning with a polar scope very easy!

Mike

Hi Mike
Yes I did that with Stellarium and watched the SCP move till it was almost in the centre of those two stars around 2035 ( I'll miss that, i'd be 101)

Barry