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iOptron polar alignment app vs PS Align

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#1 AlienRatDog

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Posted 02 May 2019 - 10:06 AM

Hello,

 

I have an iPhone and have an iOptron Skyguider Pro on its way.  For polar alignment, iOptron sells their app for $1.99 but I have downloaded a free app (there are some ads at the bottom) called the Polar Scope Align.  How do these compare?  I rather not have to pay for an app but if the iOptron app is more precise, $2 isn't going to kill me.  I like the Polar Scope Align app as it has other reticles if I ever get something else (unlikely).   Thoughts?



#2 Ishtim

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Posted 02 May 2019 - 10:39 AM

No matter what app you use, you need the "hour angle" of Polaris to determine the relative position (rotation) of Polaris to the north celestial pole (NCP). 

If you google "Polaris hour angle" you'll get a bunch of CloudyNights results discussing the method behind it.

 

There's a "schematic" showing this and the iOptron reticle out there somewhere (I can't find it back) that is really helpful...

 

I am hoping to set up mine for the Eta Aquarids this weekend if the weather permits.


Edited by Ishtim, 02 May 2019 - 10:39 AM.


#3 AstroBruce

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Posted 08 May 2019 - 05:10 PM

Get the Polar Scope Align App. It takes into account atmospheric refraction. Then upgrade to the Pro version. So many utilities you never knew you needed. You will be amazed.

 

Bruce



#4 ecuador

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Posted 31 May 2019 - 02:05 PM

Hello,

 

 How do these compare?  I rather not have to pay for an app but if the iOptron app is more precise, $2 isn't going to kill me.  I like the Polar Scope Align app as it has other reticles if I ever get something else (unlikely).   Thoughts?

It's the other way around. One of the reasons I made Polar Scope Align was because the iOptron app was way off back then - it took them a few years of mucking about to even match their hand controller, it was quite bizarre (maybe they had outsourced the app?). So perhaps now it is OK (haven't checked lately), but technically Polar Scope Align is always more precise, as it calculates things like stellar aberration, nutation etc which are often ignored as they don't make a practical difference to your polar alignment. They were mainly implemented because people would distrust the app since it gave different results than older apps, so I went "all the way" in order to exactly match US Naval Observatory published transit times, or software like Cartes du Ciel, so that it is easy to see Polar Scope Align is the correct one wink.gif

 

There's an entry in the app FAQ about accuracy that might be of interest.


Edited by ecuador, 31 May 2019 - 02:06 PM.


#5 AlienRatDog

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Posted 10 June 2019 - 03:25 PM

Thank you for your response!

#6 ecuador

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Posted 11 June 2019 - 06:31 PM

Thank you for your response!

No problem. In the meantime since more people asked I did check the current status of the iOptron app and it doesn't look good...



#7 Dave24137

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Posted 17 June 2019 - 11:19 AM

Don't use iOptron's app.

 

And a quick tip: To ensure your 12:00 position is spot-on, center Polaris on the center-line and then adjust your latitude up and down. When Polaris rides consistently along that line, you know the polar-scope is set for subsequent alignment.



#8 Tom3

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Posted 05 April 2021 - 05:40 PM

Can I use PS align pro to point at an object an ask the app to identify the object?

 

I have recently been reading and watching videos about the many things PS align Pro can do.  It is really a great app.

 

Tom



#9 ecuador

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Posted 06 April 2021 - 04:07 AM

Can I use PS align pro to point at an object an ask the app to identify the object?

 

I have recently been reading and watching videos about the many things PS align Pro can do.  It is really a great app.

 

Tom

Hi Tom. Happy you like the app. It doesn't have exactly that function. It does the opposite pretty well - if you strap your phone on the telescope, you select an object from the database and it takes you there (Push To button) - which can be accurate if you first calibrate it with a bright star that you can recognise and then "hop" to the object of interest.

 

The closest function to what you ask, is if in the DSO Database you go to Sorting->Configure and press "select by pointing" - then pointing the phone to the sky and clicking "Select Point" will list the objects from the catalogs you have selected that are closest to where you are pointing. It's the feature described on this video if you haven't seen it.


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#10 Tom3

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Posted 06 April 2021 - 04:05 PM

Hi Ecuador,

Thanks for the additional information. I have used the daytime alignment feature to align my mount.  The next time it is clear I will see how well it did. It will also be good to find stars that my mount suggest as alignment stars.

 

Tom


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