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  #1  
Old 18-06-2019, 04:50 AM
RobE
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Mount Alignment when celestial pole obscured

HI Folks,
I am entertaining moving my Meade LX200 from its ageing mount onto an EQ mount, so I can get some serious exposures done. Turns out the South Celestial is totally obscured from any point in my yard.

I was wondering how "do-able" alignment would be.
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  #2  
Old 18-06-2019, 05:50 AM
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xelasnave
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If you can see East and West should not be a problem but you will need to drift align as I dont think any programs works without a view of the CSP... however maybe that has changed or I am just not aware of such a program.
Alex
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  #3  
Old 18-06-2019, 07:25 AM
Startrek (Martin)
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You find the SCP using the Solar Noon Meridian Shadow method. Never fails I’ve used it at my 2 locations Sydney and South Coast and gets me really close to SCP to set up my tripod level and install mount ready to set home position, balancing, 2 star alignment and polar alignment using the “Synscan Polar Alignment Routine” with hand controller.About 2 or 3 iterations and I can get down to under 15 arc sec error in 15 minutes.
Finding Celestial True South using Solar noon meridian method

Items needed
1 metre length of 12mm timber dowel with a 2mm deep 90 deg cross cut into one end using a hacksaw
2 x 3 metre pieces of 1mm string cotton type
4 x weights like a brick or paver etc...
1 x straight edge, alum angle or ruler 500mm long would be good
1 x fine point black permanent marker
1 x 300mm long Stanley or quality boat type builders bubble level
1 x PC with a planetarium software program. Stellarium is a good choice as it’s free and easy to use
1 x Smartphone like an iPhone

Location
Your observing location ( solar noon meridian location too ) should be a reasonably flat and level concrete , paved or tiled ( hard surface ) area with a good view of the sun at around midday

Procedure
Erect timber dowel vertically below your preferred observing tripod position and use the 2 strings to anchors the dowel like tent guy ropes at NSEW using weights to hold it in position. Use your bubble level to ensure dowel is exactly vertical at 90 deg in all directions ( very important ) The hacksaw cuts at the top of the dowel make it easy to adjust NSEW
Pick a sunny day
Start your PC mid morning and open Stellarium. Rotate your cardinal point to the North position and raise view up until you see the Sun
Click on the Sun and then click on the clock , move the time forward or backward to the point where the Suns Alt/Az degrees goes from 359 deg to 0 deg or exactly bisecting the North South meridian line ( refer to top left hand data on screen for Az/ Alt deg )
Record this exact time which is Solar Noon ( eg 12.35pm )

Go to your observing location 10 minutes before Solar noon with your smartphone , ruler and permanent marker. The dowel should be casting a 12mm wide +500mm long shadow on the surface
At exactly Solar Noon time mark a thin line on the ground from the base of the dowel outwards along the exact centre of the shadow for at least 500mm ( be as precise as you can )

This line is the Celestial Meridian (True North South )

Use this line to align your tripod to True South
I found this method far more accurate than any app or compass with magnetic declination

Hope the above helps, there are numerous other ways to find true celestial south but this one works for me and has never failed at 2 different locations ( the sun never fails )
Cheers
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  #4  
Old 18-06-2019, 07:37 AM
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doppler (Rick)
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Drift align is the easiest method especially if you have a DSLR camera.
https://www.cloudynights.com/article...ert-vice-r2760
Rick
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  #5  
Old 18-06-2019, 08:59 AM
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xelasnave
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Quote:
Originally Posted by Startrek View Post
You find the SCP using the Solar Noon Meridian Shadow method. Never fails I’ve used it at my 2 locations Sydney and South Coast and gets me really close to SCP to set up my tripod level and install mount ready to set home position, balancing, 2 star alignment and polar alignment using the “Synscan Polar Alignment Routine” with hand controller.About 2 or 3 iterations and I can get down to under 15 arc sec error in 15 minutes.
Finding Celestial True South using Solar noon meridian method

Items needed
1 metre length of 12mm timber dowel with a 2mm deep 90 deg cross cut into one end using a hacksaw
2 x 3 metre pieces of 1mm string cotton type
4 x weights like a brick or paver etc...
1 x straight edge, alum angle or ruler 500mm long would be good
1 x fine point black permanent marker
1 x 300mm long Stanley or quality boat type builders bubble level
1 x PC with a planetarium software program. Stellarium is a good choice as it’s free and easy to use
1 x Smartphone like an iPhone

Location
Your observing location ( solar noon meridian location too ) should be a reasonably flat and level concrete , paved or tiled ( hard surface ) area with a good view of the sun at around midday

Procedure
Erect timber dowel vertically below your preferred observing tripod position and use the 2 strings to anchors the dowel like tent guy ropes at NSEW using weights to hold it in position. Use your bubble level to ensure dowel is exactly vertical at 90 deg in all directions ( very important ) The hacksaw cuts at the top of the dowel make it easy to adjust NSEW
Pick a sunny day
Start your PC mid morning and open Stellarium. Rotate your cardinal point to the North position and raise view up until you see the Sun
Click on the Sun and then click on the clock , move the time forward or backward to the point where the Suns Alt/Az degrees goes from 359 deg to 0 deg or exactly bisecting the North South meridian line ( refer to top left hand data on screen for Az/ Alt deg )
Record this exact time which is Solar Noon ( eg 12.35pm )

Go to your observing location 10 minutes before Solar noon with your smartphone , ruler and permanent marker. The dowel should be casting a 12mm wide +500mm long shadow on the surface
At exactly Solar Noon time mark a thin line on the ground from the base of the dowel outwards along the exact centre of the shadow for at least 500mm ( be as precise as you can )

This line is the Celestial Meridian (True North South )

Use this line to align your tripod to True South
I found this method far more accurate than any app or compass with magnetic declination

Hope the above helps, there are numerous other ways to find true celestial south but this one works for me and has never failed at 2 different locations ( the sun never fails )
Cheers
High Martin
How do you work out solar noon?
I used what is essentially your method only a couple of days ago starting the process to establish a true North South line...I worked out that at 152.5 longitude I should mark the line at 6 minutes before noon on the clock..I cant recall the way I arrived at this time however☺.
Alex
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  #6  
Old 18-06-2019, 09:39 AM
Startrek (Martin)
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Alex
Follow my procedure
You will need Stellarium on your laptop ( it’s a free download ) Set Stellarium to the correct time and date as your laptop ( laptop time should be correct if updated on line )
Open Stellarium, drag the screen across to the North meridian line , on the Stellarium time clock manually forward time to 11.55am , click on the Sun , a window appears in the top left corner ( see photo ) look at Az Alt data counting down towards 0 deg , once it hits 0 deg, mark your time on your smartphone , look at Stellarium , the sun should be crossing in the centre of the north south meridian line or North South Celestial Pole line ( see photo )
As it’s winter the sun is quite low , so your shadow on the dowel will be very short , this method still works in winter but obviously more accurate in Summer
Hope the above makes sense ( photos help )
Cheers
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  #7  
Old 18-06-2019, 09:48 AM
Startrek (Martin)
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Obviously this method works best on a sunny day
Also the dowel has to be perfectly straight , I bought a 1.2m length of dowel from Bunnings and realised later than it was like a banana which caused my SCP line to be a few degrees out
Maybe a aluminium rod or steel rod 12mm in dia might be more accurate
Ground must fairly flat and level also , no ruts , dips etc
I found this method on a survival website if you get lost in the bush , I just added Stellarium in it to get an accurate solar noon time
Cheers
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  #8  
Old 18-06-2019, 10:16 AM
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The_bluester (Paul)
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The other methor as mentioned would be a drift alignment, if you are using a guide camera there are easy tools for it in PDH2. You need to calibrate PHD2 (Which will probably throw a warning about poor calculated angles) and then if you work it out you can use the drift alignment routing that is built in to it to work out which direction to move the mount.

If you drift align, do the azimuth first (Pointed on the equator nearest the zenith) as any azimuth error will show up mixed in with altitude error if you try to do the altitude first where if you are on the equator and with the mount almost wanting to do a meridian flip (For a GEM) there will be almost no altitude error mixed in with the azimuth.

To go back to the earlier point, if PDH2 is calibrated then you can see if the scope is moving north or south of the selected star and work out which way to move the mount from there. Just remember always to be pointed either east of or west of the zenith or the direction you need to move will be reversed.
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  #9  
Old 18-06-2019, 10:49 AM
Startrek (Martin)
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I could be totally mis understanding Robs enquiry but but I think maybe he just wants to know how to set up the new EQ tripod to face true south and line up with the SCP as he’s been using an Az Alt mount which does not require this ??
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  #10  
Old 18-06-2019, 02:07 PM
Astronovice (Calvin)
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Solar Noon

Quote:
Originally Posted by Startrek View Post
Alex
Follow my procedure
You will need Stellarium on your laptop ( it’s a free download ) Set Stellarium to the correct time and date as your laptop ( laptop time should be correct if updated on line )
Open Stellarium, drag the screen across to the North meridian line , on the Stellarium time clock manually forward time to 11.55am , click on the Sun , a window appears in the top left corner ( see photo ) look at Az Alt data counting down towards 0 deg , once it hits 0 deg, mark your time on your smartphone , look at Stellarium , the sun should be crossing in the centre of the north south meridian line or North South Celestial Pole line ( see photo )
As it’s winter the sun is quite low , so your shadow on the dowel will be very short , this method still works in winter but obviously more accurate in Summer
Hope the above makes sense ( photos help )
Cheers
Another option to get solar noon for any location is www.sunrisesunset.com/Australia
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  #11  
Old 19-06-2019, 08:23 AM
Hemi
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Hi, I was/am in the same position.

This is what I did....

It’s quite easy to get roughly polar aligned.
1. Firstly: get your mount setup to home position: the following link is brilliant.

https://m.youtube.com/watch?v=

Next

You need a compass, inclinometer and a roughly leveled mount.

2. Point your telescope and mount to face true south. (Magnetic south plus offset for your location, can be found online). Can be approximate.

3. Raise the altitude adjustment of the eq mount to your latitude. (Found online), then fine tune using an inclinometer (iPhone worked for me). Again it is approximate.

4. Fire up the mount and add you location details. And align the GoTo.

5. Use the polar align routine (I’ve done this with celestron and SW) flavors. Follow the instructions. (You don’t use the controller, just the mechanical azimuth and altitude bolts)

6. Switch off. Loosen the clutches. Get the scope back to home. Redo GoTo, redo polar alignment.

7. You can re iterate as many times as you like. 3 worked for me, more yielded no improvement.

8. If you have ascom and a camera all working , then you can Switch over to that and use a windows program called PEM PRO. This has a polar alignment wizard. That will fine tune further if required.

I struggled for quite a while, but this worked very well for me. I have been getting 5m unguided at 700mm focal length.

The thing to remember is the initial polar alignment, where you plonk down your scope, doesn’t have to be super accurate. I only used a iPhone compass and inclinometer despite the caveats of magnetic interference etc so YMMV.

Good luck, and don’t forget to enjoy the process of getting there....all to easily done.

Cheers
Hemi
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  #12  
Old 19-06-2019, 10:52 AM
Martin_S
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Here is another site that may be useful for finding solar noon

https://www.esrl.noaa.gov/gmd/grad/solcalc/
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