Advice on polar aligning if SCP is obscured

[lineout]

Hi all,


Have a question I hope someone can help me with.


What method can I use to polar align an EQ mount if the SCP is obscured behind trees? I realise I can observe from a different location but this is for observing from my backyard. And yes one option is to chop down the trees but that's not possible as they aren't on my property.


Regards

[rustigsmed]

what type of mount are you using?

these will help
http://www.iceinspace.com.au/63-498-0-0-1-0.html

http://www.iceinspace.com.au/63-405-0-0-1-0.html

I've heard the 'solar noon method' is very accurate although I haven't tried it. will try and find a link

Russ

[lineout]

Two mounts:

SW Star Adventurer
SW AZ-EQ6 GT

[rustigsmed]

the AZEQ6 GT should be fairly easy.
after setting the mount up by using a compass and level, select two star alignment then polar alignment routines. repeat a few times as per the manual iterative adjustments will get you there.

the star adventurer I am not familiar with I would recommend the solar noon and using a level. then mark where the tripod legs are on the ground so you are close when you setup again.

[lineout]

Just on the AZ-EQ polar alignment. I've heard that there is a software polar alignment option. So does this mean I point the mount in the rough direction of the SCP and then do fine tuning with the software option?

[rustigsmed]

nearly correct, if you are just using the mount in AZ mode you can probably just do a 2 star align and it will be fine for visual work.
for photography, the two star alignment feature allows the mount to figure out how far off your alignment is. you then select polar alignment, and that will require you to centre the star by manually adjusting the mount to recenter the selected star.

[lineout]

And therin lies my probem. I can't see the SCP so won't be able to realign it.

[rustigsmed]

it uses two stars you select not the SCP.

that's why it takes a few iterations, I do it atleast one on each of the stars selected.

[redbeard]

[QUOTE=lineout;1183711]Hi all,


Have a question I hope someone can help me with.


What method can I use to polar align an EQ mount if the SCP is obscured behind trees? I realise I can observe from a different location but this is for observing from my backyard. And yes one option is to chop down the trees but that's not possible as they aren't on my property.


Regards[/QUOTE

The software Alignmaster is the go. It works well and a search on it here on IIS should show lots of info. The trick with this software is to align your mount using a compass to get close to polar and ensure your mount is level. For me in Adelaide I level then align to 172 deg and then use Alignmaster. With Alignmaster you pick 2 stars from its database that you can see in the sky.

Cheers

Damien

[jjz]

Interesting thread, I'm also a newbie and my alignment is still a bit hit and miss for photography purposes.





Hi Russell, when you say "repeat a few times" do you need to park/reset/restart the mount between alignment routines?

Do you use the same 2 stars when repeating the alignment the second/third times?

When selecting the 2 star alignment does the stars location make a difference? ie is lower on the horizon better, is S and W better than N and S?



Thanks
JJZ

[lineout]

I think he's saying you should do the 2 star alignment a few times over to get the alignment more precise.

One question for everyone. I've heard you can doa three star alignment as well which gives more precise alignment. Correct or not?

[rustigsmed]

Hi JJZ,

nope, no need to park.
Step 1: Two star alignment
Step 2: Polar alignment routine (in handset)
- with the routine it deals with one star. I usually use one of the ones just used in the two star alignment. the handset gives instructions on when to move the mount with the handset and when do use the bolts.

Step 3: Two star alignment
Step 4: Polar alignment routine (I usually go to the other star I used in the two star alignment).
Step 5: Two star alignment.
Step 6: back to step 2 and continue as many iterations as required till you are the error closer to 0 (handset will tell you).

It may take a few goes going back forth between the two stars during PA routine.

I always finish with a 2 star alignment after PA routine.



Yep :thumbsup:

Its not necessary to do a 3 star alignment - it can be used to help account for cone error. I would just try and select stars that aren't too close together with one of them in the area where you are wanting to image (if imaging).

Just make sure your firmware is 3.35 or above (if its in the 3 series - I think the newest is 3.37).

[doppler]

I only have a basic tracking mount (no computer or goto) but have found this photographic version of drift aligning very usefull.

Level the mount, set the latitude and do a rough compass alignment. Attach a camera and set it to bulb, with the motor drive turned off release the shutter and let it run for around 30sec then turn the drive motor on (run the motor fast to speed up the trails) and continue for another 30sec. You will get v shaped star trails. One line is where the stars are drifting naturally and the other is where the telescope drive is heading. Slowly adjust the mount left or right until the v dissapears and the line is straight. (if the v gets wider you are moving the mount in the wrong direction)

[Somnium]

Up until recently I have used drift alignment , Forrest Tanaka has a good YouTube tutorial for getting great polar alignment https://m.youtube.com/watch?v=zQB6UnrTEEM Towards the end of the video. But recently I have switched to using astrotortilla and its polar alignment method. It will take 2 shots and tell you exactly how Far East or west you are and then another 2 for Altitude. You can really dial it in with this tool, I love it.

[jjz]

Thanks Russell, I was skipping steps 3/5 makes sense now :)

JJZ

[lineout]

This is really good, thanks. Once the clouds clear from Sydney I'll break out the mount & give it a go.

[lineout]

So just confirming. If I use the steps outlined above I don't need to have the SCP in view? ie if it's obscured I'm still ok to use this method.

[rustigsmed]

Glad I could help out. Just make sure the firmware is a recent version I had trouble with the one that came out of the box and it needed updating.



no worries, fingers crossed the clouds head off soon!



that is correct, I can't see the SCP either :thumbsup:

[lineout]

:party2:

[skysurfer]

Well rather simple.
This can be achieved by doing a two 'star' alignment of which one 'star' is the zenith. The other star can be a real star of a planet not higher than 30 degrees and not more than 30 degrees from the equator.
And you need, of course an equatorial mount and a level to point the telescope at the zenith and an inclinometer or a wedge angled at your latitude to set the polar axis to the proper elevation.

http://skysurfer.eu/eqmount.php

or here a video I made in Feb 2014 (explained in daylight but, of course, this also works even better after dark):

http://skysurfer.eu/jwplayer/video.php?v=L1ZpZGVvcy9za3kvUG9sYXJ fYWxpZ25tZW50Lm1wNDo6OjYwMA==

I used this method in Bali where the pole star is too low (8 degrees) and made frames of 30 seconds with a FL of 500mm.