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Alignment star choice

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6 replies to this topic

#1 mintaka77

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Posted 30 May 2020 - 04:27 AM

My Celestron AVX, recently fixed with new motor, chooses Arcturus as its first alignment star.  The next ones that come up include Vindemiatrix and Zosma but these are very close in the sky.  Surely it should choose a second alignment star far away?  But I scroll through all the stars, and for example, Vega does not come up!  Yet it is the obvious other star to choose at this time of year.  Also stars in Ursa Major do not come up on the list of allowed second stars.  It is only when I add a calibration star that I can add any star that I like.  With this trouble, I cannot get the alignment to work -  if I use Arcturus and Vindemiatrix, and then ask it to go back to Arcturus again, it doesn't get it quite right.  My polar align and balancing are reasonably OK.  

Any thought??!!



#2 wrnchhead

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Posted 30 May 2020 - 05:37 AM

My AVX would definitely not perform if I were only doing a two star alignment. How does it do with the full set of 4 calibration stars?

#3 ButterFly

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Posted 30 May 2020 - 06:10 AM

The alignment stars must be on the same side of the meridian (press 7 to switch sides).  The calibration stars must be on the other side of the meridian.  Aim for at least 30 degrees in each axis between the stars.

 

It very much depends on what time you tried this alignment whether Vega was on the same side of the meridian as Arcturus.  If it was, check your filter limits.  The lower limit could have been too high for Vega to be displayed based on its altitude at that time.  If the lower limit is fine after checking, make sure your latitude and longitude are set correctly so that it filters the alignment star list properly.

 

Goto alignment is only counting encoder ticks.  Polar alignment and balancing have nothing to do with accurate goto.  Both can be way off and the gotos will still be fine if alignment is done well. 



#4 spereira

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Posted 30 May 2020 - 06:51 AM

Moving to Celestron Computerized Telescopes for a better fit.

 

smp



#5 whizbang

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Posted 30 May 2020 - 08:24 AM

It sounds like you are using "Auto 2 Star" alignment.  You don't have to accept the suggested star.  Scroll up or down to select a star that is further away your first star.



#6 mclewis1

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Posted 30 May 2020 - 09:38 AM

Use the E/W filtering (press the Menu key) when you are presented with alignment stars that don't work for you. The NexStar firmware will select alignment stars only from one side of the meridian, and pressing Menu will select stars from the other side (giving you more appropriate options for your skies). 



#7 mintaka77

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Posted 30 May 2020 - 12:08 PM

That is most interesting - thanks to this, perhaps I'll have better luck tonight ....




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