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Setting circles and equatorial platforms

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#1 IanT

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Posted 23 April 2008 - 12:52 AM

Hello to all
This question probably has a simple answer but it sure has done my head in. On my Dob base I have constructed a setting circle similar to those described in many posts to this forum. I use a digital inclinometer for the vertical axis. I take care to level the base before dialing in the co-ordinates of the objects I wish to view. The system works well. Now, if I were to place the base and 'scope on an equatorial platform (Roundtable type), how could I use my circle/inclinometer on what is now a base tilted to 37 degrees?
Cheers
Ian

#2 snogum

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Posted 23 April 2008 - 09:06 AM

You would then us Right Ascention & Declination co-ordinate system instead of Altitude and Azumith system.

Your Laptop or palm pilot should be able to output corodinates in RA and Dec just as easily as it did Alt & Az

#3 snogum

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Posted 23 April 2008 - 09:07 AM

Oh and G'Day mate

Welcome to CN

#4 IanT

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Posted 23 April 2008 - 07:26 PM

Thanks for that. It seemed so simple I assumed that there must be a catch!!
Cheers
ian

#5 CosmoJoe

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Posted 17 October 2012 - 06:29 PM

i don't understand. if RA cooridates constantly move. would the RA circle need to be reset everytime you reset the platform? maybe this is a little over my head. i need to see a platform with circles in action to understand i suppose.

#6 Phil Sherman

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Posted 18 October 2012 - 08:39 AM

To use your RA circle, you need to set it to the RA of your current target just before moving the scope. You can then use it to point the scope at a different RA. Pointing accuracy degrades at the rate of one degree every four minutes so you should be able to use the setting circle to find your new target.

On my GEM, the RA circle moves with the mount when tracking. When slewing, the circle remains fixed and the RA changes as the mount moves.

Phil

#7 CosmoJoe

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Posted 18 October 2012 - 01:04 PM

and that will work if the RA scale is on the dob base?

#8 cheapersleeper

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Posted 18 October 2012 - 01:42 PM

His setting circles are Alt/Az, he can't use them to track his position when the platform is running. One of the apps for the Palm Pilot used to be able to calculate Alt/Az for the objects on a platform so I assume there are other apps that can.

#9 SteveInNZ

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Posted 18 October 2012 - 01:56 PM

I think that this advise is wrong. With a platform your scope is still sitting with the base level and is still operated in Alt-Az mode to locate an object.

#10 CosmoJoe

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Posted 18 October 2012 - 06:52 PM

that's what i thought. so to use manual circles i would basically have to level the platform and only get half the tracking?

#11 CosmoJoe

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Posted 18 October 2012 - 07:36 PM





Thank you, from what I can tell manual setting circles + eq platform= useless. Fork mount conversion is the way to go

#12 cheapersleeper

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Posted 18 October 2012 - 08:51 PM

Astromist for the palm pilot had a function that corrected for a platform's movement while calculating Alt/Az. I assume some other app might do that as well. That would make the combination useable.






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