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Author Topic: Comp article-Rough daytime polar alignment.  (Read 7874 times)

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Offline davemahoney

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Comp article-Rough daytime polar alignment.
« on: 12:30:33, 26 March, 2007 »
These tips are aimed at people without GOTO scopes.

As the days are now getting longer, any time setting up is more time imaging. :D
A few simple tools are required to obtain daylight rough polar alignment.
A magnetic compass.
A spirit level, (2 way, caravan type)
A home made theodolite.
Oh, and knowing your latitude, (can be found from many websites)

First set up your tripod, level the tripod by placing the spirit level on the tripod spreader and adjust tripod until both bubbles are within the lines.
Assemble the mount and OTA onto the tipod, then recheck the tripod level and adjust if necessary.
Using the compass align the OTA to North, (be carefull not to hold the compass to close to any steel fittings). Then using the spirit level, adjust the OTA until it is level.
Recheck levels and North alignment.
Ok, now for the theodolite. I made one from a protractor with a hole drilled at the point where the 0oand 90o lines cross, (see photo)
Tie a piece of cotton through the hole and a weight to the other end of the string, (make the string longer than the radius of the protractor).
Altitude setting. Hold the protractor under the OTA and adjust the altitude setting of the mount until the string on the protractor bisects the angle on the scale to match as close as possible your Latitude.
You should now have achived a rough polar alignment, leave the scope in this position until it is dark enough to see Polaris, then finalise your alignment.

Dave. :)
p.s. I think newcomers is the place for this?
Another tip. Whilst venus is visible at twighlight it is a great target for setting up the finder scope.



[attachment deleted by admin]
Skywatcher ED80 pro
Celestron 114mm short newt.
ASTSC1C Webcam.
Fuji finepix s3500.
Bresser 10x50 bins.
Switched Systems electronic focuser.
And a couple of eyepieces and filters.

Offline the fordster

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Re: Comp article-Rough daytime polar alignment.
« Reply #1 on: 13:24:23, 26 March, 2007 »
Nice article, Dave! :cool:

Offline NickH

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Re: Comp article-Rough daytime polar alignment.
« Reply #2 on: 14:23:13, 28 March, 2007 »
Yup good stuff, should be a sticky

Celestron C11: DSI-C/Toucam Pro 2 ICX mod and SC1.5 mod/ Meade LPI/EOS300D/ED80/WO80ZS/Shoestring guider. PST/PST CaK/ART285

No time....always bloomin cloudy...need to build the Obsy..

Offline dciobota

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Re: Comp article-Rough daytime polar alignment.
« Reply #3 on: 14:40:29, 30 March, 2007 »
  Excellent Dave!  Yup, I'd make it a sticky and post it in the telescope section too.
PLEASE REMOVE ME

Offline disraeli

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Re: Comp article-Rough daytime polar alignment.
« Reply #4 on: 12:06:26, 31 May, 2007 »
Dave, Sounds easy, but still haven't got it right.  I am at exactly 53.0 north but at a height above sea leval of 790 feet or 240 meters.  What should you allow for the height, and finally a stupid question I have an old Meade LXD 55 10 inch Newtonian, when I look through the polar alignment scope with the led light turned on, I see  a cross with a vertical line down and the a figure 40' the a circle and then 60' what's this circle for? looks like it could be of help but have no idea.  Fred.
Fred.----------------------------------------------------------------------------
HEQ5 pro, TMB 92 Triplet with Televue   TRF-2008 x0.8 flattener, ATIK 4000LE OSC. 300mm telephoto lens with Meade DSI IIIC as Guide Camera,  Guiding with PHD, Phillips SPC900NC webcam. Various camera lenses all wit

Offline davemahoney

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Re: Comp article-Rough daytime polar alignment.
« Reply #5 on: 18:01:30, 31 May, 2007 »
Hi Fred.
Adjustments for altitude will make a negligable difference for most users, as the angular distance from your height to sea level measured from the celestial pole would be miniscule.
As far as the polar scope is concerned, i confess to never using one :roll:
But the circles you can see are measures of arc seconds, so these circles are a guide to assist in a more accurate alignment, as you know polaris is not exactly at the celestial pole, but orbits it by about 1 third of a degree or 20 arc minutes, so if you know at which point in it's orbit polaris is located you can use these scales to offset the scope accordingly. I Know of some free software on the web to help with polaris's position at any given time, i'll hunt it down and post the link, The link is not working at the moment, but here is a link to free stuff which has the web site included.
http://www.noao.edu/outreach/kpvc/imaging-workshop/essential-software.html

Dave.
Skywatcher ED80 pro
Celestron 114mm short newt.
ASTSC1C Webcam.
Fuji finepix s3500.
Bresser 10x50 bins.
Switched Systems electronic focuser.
And a couple of eyepieces and filters.

Offline disraeli

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Re: Comp article-Rough daytime polar alignment.
« Reply #6 on: 09:07:14, 02 June, 2007 »
Dave,  Thanks for that. Have done another alignment with mount horizontal, have fixed a very long piece of wood to the OTA ring clamps so that the compass is about 3 feet from the mount and this makes it very easy to get an accurate reading. Thanks again.  Fred.
Fred.----------------------------------------------------------------------------
HEQ5 pro, TMB 92 Triplet with Televue   TRF-2008 x0.8 flattener, ATIK 4000LE OSC. 300mm telephoto lens with Meade DSI IIIC as Guide Camera,  Guiding with PHD, Phillips SPC900NC webcam. Various camera lenses all wit

Offline Scotty

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Re: Comp article-Rough daytime polar alignment.
« Reply #7 on: 12:36:16, 20 February, 2008 »
The circle is where polaris should be - you need to rotate the polar scope depending upon the time of day and day of year.
Celestron C6S-GT (XLT)
http://scott.donnel.ly

Offline disraeli

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Re: Comp article-Rough daytime polar alignment.
« Reply #8 on: 16:04:43, 20 February, 2008 »
Scotty,  Thanks for that.   I hadn't realised till now that the image in the Meade Polar Scope is inverted. I guess if I rotate the axis to match the position of Polaris, which I can get from Jason Dales program, I ought to get it fairly close.  The weather has changed here in North wales so no scope out for the next few night.  Fred
Fred.----------------------------------------------------------------------------
HEQ5 pro, TMB 92 Triplet with Televue   TRF-2008 x0.8 flattener, ATIK 4000LE OSC. 300mm telephoto lens with Meade DSI IIIC as Guide Camera,  Guiding with PHD, Phillips SPC900NC webcam. Various camera lenses all wit

Offline tony.673

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Re: Comp article-Rough daytime polar alignment.
« Reply #9 on: 15:45:25, 05 April, 2008 »
Great set of instructions Dave. If anybody is interested there is a great site where you can get a printout of a protractor that I used. I printed and laminated mine for regular use.

http://www.ossmann.com/protractor/

Tony
102mm f6 refractor, HEQ5, AA Gpcam130c, Neximage, SPC900, Celestron 15x70 binos, Canon 550D 70-300mm, 18-250mm, 400mm f6.3 & nifty fifty.

Offline davemahoney

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Re: Comp article-Rough daytime polar alignment.
« Reply #10 on: 16:28:10, 05 April, 2008 »
Thank for the link, Tony.
Since i did the article, many diy shops are now selling digital protractors quite cheap, and these will obviously be more accurate.

Dave.
Skywatcher ED80 pro
Celestron 114mm short newt.
ASTSC1C Webcam.
Fuji finepix s3500.
Bresser 10x50 bins.
Switched Systems electronic focuser.
And a couple of eyepieces and filters.

Offline Tim036

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Re: Comp article-Rough daytime polar alignment.
« Reply #11 on: 20:40:49, 21 December, 2008 »
These tips are aimed at people without GOTO scopes.

As the days are now getting longer, any time setting up is more time imaging. :D
A few simple tools are required to obtain daylight rough polar alignment.
A magnetic compass.
A spirit level, (2 way, caravan type)
A home made theodolite.
Oh, and knowing your latitude, (can be found from many websites)

First set up your tripod, level the tripod by placing the spirit level on the tripod spreader and adjust tripod until both bubbles are within the lines.
Assemble the mount and OTA onto the tipod, then recheck the tripod level and adjust if necessary.
Using the compass align the OTA to North, (be carefull not to hold the compass to close to any steel fittings). Then using the spirit level, adjust the OTA until it is level.
Recheck levels and North alignment.
Ok, now for the theodolite. I made one from a protractor with a hole drilled at the point where the 0oand 90o lines cross, (see photo)
Tie a piece of cotton through the hole and a weight to the other end of the string, (make the string longer than the radius of the protractor).
Altitude setting. Hold the protractor under the OTA and adjust the altitude setting of the mount until the string on the protractor bisects the angle on the scale to match as close as possible your Latitude.
You should now have achived a rough polar alignment, leave the scope in this position until it is dark enough to see Polaris, then finalise your alignment.

Dave. :)
p.s. I think newcomers is the place for this?
Another tip. Whilst venus is visible at twighlight it is a great target for setting up the finder scope.



[attachment deleted by admin]


OTA ?   Ah !

My Theory might be Ok (ish) but not so the Jargon of the day !

So if any one else is puzzled:-

http://www.popastro.com/phpBB2/viewtopic.php?t=1202

:)

Tim

Offline Timothy Brown

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Re: Comp article-Rough daytime polar alignment.
« Reply #12 on: 13:36:27, 09 January, 2015 »
Hello,

One newby question, if I'm using a magnetic compass to find north do I need to factor in the offset between true north and magnetic north? or is the resulting error sufficiently small that it can be ignored?

Regards

Timothy

Offline Nomis Elfactem

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Re: Comp article-Rough daytime polar alignment.
« Reply #13 on: 16:23:19, 09 January, 2015 »
The latter rather than the former, depending upon what mount/scope you're using and what level of imaging you're doing.  If you're using a "basic" mount that doesn't have a polar scope and a scope with a short focal length then magnet north will be adequate and then if needed you can use other techniques (e.g. drift alignment) to get it more accurate.

HTH's
S.
Simon

Scopes: Astro-Tech AT-111EDT Triplet, TS65ED Quad, Orion ST80, Modded PST-90 Solar Scope, PST Cak (on loan)
Cameras: SXVF H694, Atik 16ic, Canon EOS 600d, DMK41, DMK21, QHY 5L-II (mono & colour)
Accessories: SX USB Filter Wheel, SX OAG, Baader LRGB Ha SI OII Filters, SharpSky Focuser
Mount: EQ6 (EQMOD), SW Star Adventurer, plus a lot (and I mean a lot) of other bits and pieces

Offline mechanoid

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Re: Comp article-Rough daytime polar alignment.
« Reply #14 on: 17:30:35, 22 January, 2015 »
There's a much faster way to do accurate  polar alignment. It used to take me about 30 seconds to get out the mount and set it up, aligned within about 15 arc secs or less. But you'll have to invest a bit of time and effort (there's always a catch).

Before I got an observatory, I fixed a permanent pillar into concrete, surrounded by a circular wooden decking. The pillar was faced with wood strips, and topped with a fancy sundial, so it was a garden feature rather than an eyesore !  However, the sundial was easily removable, underneath being a kinematic mounting plate.  Think of the brass plates with three radial grooves you see on the old concrete trig points. Same principle.

I made a three armed spider, permanently attached to the bottom of the mount.  This had three adjustable leveling screws with conical ends that located into the grooves in the pillar. The 3 grooves were actually made of pairs of short lengths of 10 mm dia circular rod.  That way the conical screws form a true kinematic contact (a V groove won't).  There were an additional three screws close to the adjusters, in loose fitting holes, that screwed into the base to clamp everything firmly together.  Once the mount was leveled (the three screws) and polar aligned, it could then be removed and replaced simply by undoing the three clamping bolts.  I found that it would go back accurately enough for my GoTo mount to put a reference star in the field of view without any further adjustment. (Mark the start positions of the axes with some white tape).

As far as I'm aware, no one makes anything like this.  A pity, as I found it really useful and it shouldn't be expensive to make.  Maybe someone will. There's no accurate machining, I made mine from 1" square steel bar, a hacksaw and a bit of welding.  The decking took longer !

Another tip is to buy a weatherproof telescope cover.  I used to set my equipment up in the daylight, then cover it up. That way it had time to cool down, and was protected if the weather changed in the meantime.  I sometimes used it at the end of a long night, so I could finish quickly and tidy up in the morning. Saved a lot of time and hassle.

Skywatcher Quattro 200mm C/F, Vixen GPDX, QHY10
Skywatcher ST80, QHY5II, PHD2
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