Cg5 goto accuracy question

[ykket]

Hey folks,

I bought a used Celestron CG5 GT and unfortunately haven't been able to use it due to the snowy and cold winter here. I have a Celestron 127slt attached to this mount. I went out tonight to take a quick look at the moon. I did a very rough polar alignment and then just did a solar system align on the moon. I had all the information entered correctly and when it slewed, it was WAY off. Even once I had it on the moon, changing targets (Jupiter for instance), it was still off. Could it be due to the polar alignment not being exact?  Being that I bought it used, does it make sense to do a factory reset on the hand controller to remove any settings the previous owner had? Mainly, just looking for advice

Thanks

[sheldondave]

Hi'

A factory reset may help, but you will get much better results if you were to do a 2 star alignment at the very least, as in my experience a Solar System alignment is not that accurate.

Good luck,

Dave.

[ykket]

Thanks, I will try that. Last time I looked at the stars to align I had no idea what they were haha. Different stars than my original mount.

[ronin]

Use stars for alignment.

They are "fixed" whereas planets, moon are not and the position has to be calculated.

Then throw in that planets will appear to move "backwards" and the positional accuracy is a little suspect at the end. I suspect you end up with an approximate position more then anything.

The electronics and computing available is very limited.

[msh1]

is your lat/long set right is the date set as the american std month/day/year this catches a lot of people out 

do a 3 star align not solar system align choose a star in handset goto it align in finder then eyepiece goto your next star it should be fairly close then 3rd star the gotos are pretty bang on with that mount

mark

[RobertI]

Not sure specifically where the problem lies with approach you are using but I can reassure you that the CG5 GT has very good goto accuracy with the right appraoch. Do you have a polarscope for doing your rough alignment and is it centrally aligned in the RA axis?

When set up using the approach below I can get the object within with field of view using the goto even at 200x magnification with my C8.

My approach is a follows:

• Ensure that the polar scope is central to the RA axis - takes around 5 mins and can be done during the day. Plenty of videos on web.

On the night:

• Balance everything in RA and Dec.
• Do a rough align to celestial north using the polarscope
• Do an accurate align of using the polarscope with the RA set to the Position Angle of Polaris. I use a iPad app to get the position angle. Takes about 3 minutes when you get adept at it. Again there are videos on the web.
• Do a three star align.

HTH

Rob

[ykket]

Thanks everyone. I still have a lot to learn when it comes to this mount. I've only taken it out a couple times. I am sure once I get the steps down I'll have no issues going forward.

[ykket]

Couldn't figure out how to edit my last post :|

Rob, what iPad app do you use? I do have the polar scope, learning to use it properly.

Thanks

[RobertI]

The app is called Polar Align by George Varros and it costs a couple of dollars.

It does take a bit of time to get acquainted with the process of centring the polar scope in the RA axis and then polar aligning the mount on the night, but it is really quick when you get the hang of it. I actually really enjoy the process now!

I also find a polar scope illuminator to be very useful if you don't have one, such as this:

http://www.firstlightoptics.com/skywatcher-mounts/polar-illuminator-for-eq3-2eq5-mounts.html

Rob

[orley]

The goto accuracy of this mount is excellent as long as the time, date, daylight saving time and lat/long data are all entered correctly and that it has a fairly accurate polar alignment. With mine I extended the legs to full height, drilled small holes in the patio to put the feet in so that the mount was in the same place/height each time, then performed a polar alignment. All I had to do after that was plonk the mount into that same spot and solar system alignment was pretty accurate. Would always do a 2 + 4 for photography though.