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First attempt at polar alignment
Aug 17, 2017 11:15:53   #
big-guy Loc: Peterborough Ontario Canada
 
With the eclipse coming up on Monday and clear skies last night, first in quite a while, I figured I better at least try and do a polar alignment. I am using the Skywatcher Star Adventurer with advanced firmware. For the life of me I could not locate Ursa Major unless I stood out in the middle of the street, but on my back deck it just wasn't happening. OK, I got my app for sky viewing and set the longitude for my area, then tried to align the unit with what the app shows. Hmm, there is a bright star at the 8:30 mark in the polar scope so following the polar alignment for that time I moved the star to the appropriate spot on the grid. Is that Polaris? I just don't know for sure but it's a starting point. Set the camera up and tried a 180 second shot to see if there was any trailing going on. In the camera it was dark but looked pretty pinpoint to these old eyes. Changed the ISO to 400 and ended up with cream skies but still looked pinpoint to me. Let's try a 300 sec at 100 ISO. Sky was still creamy but somewhat darker and the stars still showed as pinpoint. Get outa Dodge! Did I actually nail Polaris on the first try? Here are the 3 test shots taken in town so yes you will see LP. These are all taken with a Canon 50D with 24-105 L set at 105 mm (168 mm equivalent) and f4. Comments more than welcome, especially from the pixel peepers. PP in LR and included lowering blacks and shadows, lightening whites and highlights, adding contrast, minimal noise reduction, white balance to more blue and I think that did it. Oh yes, I am aimed approx 15° right of Polaris, no reason, just saw some brighter stars there and had the tree tops for comparison. You can really see the trees trailing in the 5 minute exposure.

180 sec (3 minutes) f4 ISO 100 at 105 mm
180 sec (3 minutes) f4 ISO 100 at 105 mm...
(Download)

180 sec (3 minutes) f4 ISO 400 at 105 mm
180 sec (3 minutes) f4 ISO 400 at 105 mm...
(Download)

300 sec (5 minutes) f4 ISO 100 at 105 mm
300 sec (5 minutes) f4 ISO 100 at 105 mm...
(Download)

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Aug 17, 2017 12:24:13   #
SonnyE Loc: Communist California, USA
 
I'm not sure Peter.
But something I've always used when the sky is confused, is the big dipper.
Right off the front lipper...

Goes like this:
http://en.es-static.us/upl/2011/09/09sep14_430.jpg

http://en.es-static.us/upl/2011/09/09sep14_430.jpg

What messes me up is when I go to darker skies than home. Too many stars!
There are various apps that can help, several are free.

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Aug 17, 2017 12:38:46   #
big-guy Loc: Peterborough Ontario Canada
 
Myself included, but as I said, from the deck it wasn't happening as the BD was below and behind the big bushy trees at the back of the yard. So unless I got a big ladder....

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Aug 17, 2017 16:31:40   #
SonnyE Loc: Communist California, USA
 
big-guy wrote:
Myself included, but as I said, from the deck it wasn't happening as the BD was below and behind the big bushy trees at the back of the yard. So unless I got a big ladder....


Humm... Maybe the roof?

Or a chainsaw?

Darn, like they say in Real Estate. It's location, location, location...
And if your deck is other than concrete on the ground, you may not be happy with the vibrations it could induce into your telescope. (You'd be surprised. I found that just sitting waiting for an image to expose, if I moved my feet at all, it shown in the result. Absolutely maddening.)

Maybe somebody is trying to push you to try a different location?

Also, the Big Dipper, like the rest of the stars, rotates around the North Star (Polaris) so maybe you could get a 'shotgun' estimate of where Polaris is at a different hour?
Ever play around with Stellarium? You can run it forwards, or backwards, to different times to get an estimate. http://www.stellarium.org/
I've grown to really like it, and rely on it for my Object acquisition, and even mount control.
But Matthew clued me in to the time travel in it.

Here is a bunch of could be's, or might helps, that I found with Google.
Personally, I seem to get more from various You Tube tutorials than anywhere else.

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Aug 18, 2017 03:15:24   #
Europa Loc: West Hills, CA
 
It looks like you were very close, see some minor tailing, also may be a touch out of focus. You are very lucky to get that close just working from an app.

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Aug 18, 2017 12:23:50   #
Marc G Loc: East Grinstead, West Sussex, England
 
big-guy wrote:
With the eclipse coming up on Monday and clear skies last night, first in quite a while, I figured I better at least try and do a polar alignment. I am using the Skywatcher Star Adventurer with advanced firmware. For the life of me I could not locate Ursa Major unless I stood out in the middle of the street, but on my back deck it just wasn't happening. OK, I got my app for sky viewing and set the longitude for my area, then tried to align the unit with what the app shows. Hmm, there is a bright star at the 8:30 mark in the polar scope so following the polar alignment for that time I moved the star to the appropriate spot on the grid. Is that Polaris? I just don't know for sure but it's a starting point. Set the camera up and tried a 180 second shot to see if there was any trailing going on. In the camera it was dark but looked pretty pinpoint to these old eyes. Changed the ISO to 400 and ended up with cream skies but still looked pinpoint to me. Let's try a 300 sec at 100 ISO. Sky was still creamy but somewhat darker and the stars still showed as pinpoint. Get outa Dodge! Did I actually nail Polaris on the first try? Here are the 3 test shots taken in town so yes you will see LP. These are all taken with a Canon 50D with 24-105 L set at 105 mm (168 mm equivalent) and f4. Comments more than welcome, especially from the pixel peepers. PP in LR and included lowering blacks and shadows, lightening whites and highlights, adding contrast, minimal noise reduction, white balance to more blue and I think that did it. Oh yes, I am aimed approx 15° right of Polaris, no reason, just saw some brighter stars there and had the tree tops for comparison. You can really see the trees trailing in the 5 minute exposure.
With the eclipse coming up on Monday and clear ski... (show quote)


Hi Peter

I hope you don't mind but I had a little play with your second image,
very close to alignment hence the drift I adjusted in PS,
stretched the image slightly more in curves as I thought I could see Andromeda.

Ran the edited version through Astrometry to show the constellations & the galaxy of Andromeda.

Great start & welcome to the dark side. Marc


(Download)

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Aug 18, 2017 15:45:51   #
big-guy Loc: Peterborough Ontario Canada
 
Lucky? I am Irish you know.

Europa wrote:
It looks like you were very close, see some minor tailing, also may be a touch out of focus. You are very lucky to get that close just working from an app.

Reply
 
 
Aug 18, 2017 15:53:00   #
big-guy Loc: Peterborough Ontario Canada
 
No problems. Thanks for the welcome and tip on Astrometry.

Marc G wrote:
Hi Peter

I hope you don't mind but I had a little play with your second image,
very close to alignment hence the drift I adjusted in PS,
stretched the image slightly more in curves as I thought I could see Andromeda.

Ran the edited version through Astrometry to show the constellations & the galaxy of Andromeda.

Great start & welcome to the dark side. Marc

Reply
Nov 3, 2017 05:36:22   #
W7MEV
 
I have never had good luck aligning to Polaris since Earth's actual axis of rotation is NEAR but not ON Polaris. My best polar alignment is done using the "Drift Alignment" method (which is explained elsewhere on the web. Two good sources are:
http://astropixels.com/main/polaralignment.html
and
http://www.skyandtelescope.com/astronomy-resources/accurate-polar-alignment/
a good drift alignment will allow you to make VERY long exposures with minimum amount of autoguiding. Guiding still needed for "round" stars, but the better the polar alignment the better your mount will track on its own.

I have my scope mounted on a concrete pillar set into the ground with a couple cubic foot concrete foot so my mount is very stable, but even then an periodic "touch up" polar alignment is needed. I did try the various "polar alignment" routines in some of my software - Celestron's StarSense, for example, and found these aids to be very good, but still can't beat a good drift alignment.

With my drift alignment completed, whenever I open my scope in its home position, I am presented with Polaris just right there! Recently I took a quick shot showing Polaris and Polaris Ab. Not a great shot and no post processing, but attached just for giggles!



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Nov 4, 2017 17:59:45   #
CraigFair Loc: Santa Maria, CA.
 
big-guy wrote:
With the eclipse coming up on Monday and clear skies last night, first in quite a while, I figured I better at least try and do a polar alignment. I am using the Skywatcher Star Adventurer with advanced firmware. For the life of me I could not locate Ursa Major unless I stood out in the middle of the street, but on my back deck it just wasn't happening. OK, I got my app for sky viewing and set the longitude for my area, then tried to align the unit with what the app shows. Hmm, there is a bright star at the 8:30 mark in the polar scope so following the polar alignment for that time I moved the star to the appropriate spot on the grid. Is that Polaris? I just don't know for sure but it's a starting point. Set the camera up and tried a 180 second shot to see if there was any trailing going on. In the camera it was dark but looked pretty pinpoint to these old eyes. Changed the ISO to 400 and ended up with cream skies but still looked pinpoint to me. Let's try a 300 sec at 100 ISO. Sky was still creamy but somewhat darker and the stars still showed as pinpoint. Get outa Dodge! Did I actually nail Polaris on the first try? Here are the 3 test shots taken in town so yes you will see LP. These are all taken with a Canon 50D with 24-105 L set at 105 mm (168 mm equivalent) and f4. Comments more than welcome, especially from the pixel peepers. PP in LR and included lowering blacks and shadows, lightening whites and highlights, adding contrast, minimal noise reduction, white balance to more blue and I think that did it. Oh yes, I am aimed approx 15° right of Polaris, no reason, just saw some brighter stars there and had the tree tops for comparison. You can really see the trees trailing in the 5 minute exposure.
With the eclipse coming up on Monday and clear ski... (show quote)

Great job Guy. A really good start with the gear you are using. I'm happy with what I see.
Craig

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