GoTos


carlburton2001
 

I also had pointing issues last night after not imaging for a few weeks due to the weather.  I use a computer for observatory only and do not use my hand controller.  I thought I remembered a Win update recently and did a Restore on my computer to 9/30/2021 and pointing returned to normal. 

Worked for me but YMMV


weems@...
 

I haven’t weighed the whole setup. The C14 has a carbon tube, so it’s a tiny bit lighter than standard. The refractor is about 22lbs.  Counterweight is 2 30s, a 24, and an 18, tight against the top of the bar, plus a 10 that provides fine balance, and is 2” below the rest. So 112, but with a shorter moment arm than the OTAs. The bar also adds a few lbs.

Chip


Scott Cooke
 

Chip,
Thanks for responding. Impressive setup.  I love how you made it not much wider than the dovetail saddle.  How much weight do you think the mount is carrying?  90-100 lbs?  How much counterweight do you have?  I use 4 18lb weights with just my C14 setup for visual.  

On Sun, Oct 17, 2021 at 3:54 PM <weems@...> wrote:
Responding to Scott, here are some photos of the tandem setup on my 900. The main saddle is a DOVELM162. The tandem plate is an SBD18SS, the C14 is on another DOVELM162, with a Losmandy C14 dovetail and mounting blocks. The 6"f9 is on an ADM TGAD, with a custom riser block to match the hole patterns, and allow it to clear the raised, central section of the SBD. The scope is on a Losmandy plate that has AP mounting hole patterns, so the rings can attach to it.

To adjust out cone error for the C14, I made some brass plates to go between the plate and the blocks, which allows the safety knob to be replaced with a SS cap screw. Otherwise, the screw would go into a recess in the blocks. It's much easier to dial in the correction this way, rather than trial and error with shims, for such a heavy scope. Once the C14 is set, the TGAD allows the refractor to be made parallel. However, the TGAD does have some flexure, so the relative position of objects shifts a little in different orientations. If there's a better solution for two-axis alignment, I'd love to try it. 

With the dew shield the C14 extends nearly as far forward as the refractor, but being tail-heavy, it doesn't extend out as far in back. 

Chip




Robert Berta
 

Another thought....Do you have a location for your observing stored in the HC and are you sure you are using that one. I have a few different sites saved in my hand controller so if you have the wrong one in use it is going to throw everything off. This could also apply if you are using some software  such as The Sky or Sky Safari....make sure you have the correct observing site. If you are using Sky Safari there was a bug in a version about 2 back which had the wrong hour even when you set it correctly. I notified them and it was fixed.


Robert Berta
 

try removing both scopes and put a refractor on in standard position...centered instead of offset. See if that helps. With that much weight and I suspect not equally balanced side to side, that may be part of the issue. I have a AP 900 and AP 1100. At one time I did run a 14" SCT on the 900 by itself along with heavy full frame SBIG camera, auto guide  scope and camera, autofocuser, etc. That is a lot of possible flex culprits. I remember seeing an article about the effect of flexure....as I recall just a few thousands of an inch makes a big difference. 


weems@...
 

Responding to Scott, here are some photos of the tandem setup on my 900. The main saddle is a DOVELM162. The tandem plate is an SBD18SS, the C14 is on another DOVELM162, with a Losmandy C14 dovetail and mounting blocks. The 6"f9 is on an ADM TGAD, with a custom riser block to match the hole patterns, and allow it to clear the raised, central section of the SBD. The scope is on a Losmandy plate that has AP mounting hole patterns, so the rings can attach to it.

To adjust out cone error for the C14, I made some brass plates to go between the plate and the blocks, which allows the safety knob to be replaced with a SS cap screw. Otherwise, the screw would go into a recess in the blocks. It's much easier to dial in the correction this way, rather than trial and error with shims, for such a heavy scope. Once the C14 is set, the TGAD allows the refractor to be made parallel. However, the TGAD does have some flexure, so the relative position of objects shifts a little in different orientations. If there's a better solution for two-axis alignment, I'd love to try it. 

With the dew shield the C14 extends nearly as far forward as the refractor, but being tail-heavy, it doesn't extend out as far in back. 

Chip




weems@...
 

I agree, but the scope cradles don’t show up very often. The C14 is on an AP 16”saddle, which adds a lot of rigidity to the Losmandy bar. That’s on the AP tandem bar, which is in another 16” saddle that almost spans its length. The C14 substantially out weighs the 6”, so it’s only offset a few inches from the mount center. The 6” is on an ADM TGAD to allow collimating of the two scopes. That’s where I have the most flexing. The C14 doesn’t move to any noticeable degree. 

I’ll see if I can get a picture to post.


Chip


Jodi McCullough <jmccul@...>
 

When we had this problem, it was one of the handpaddle batteries.  Call George at AP and he can send you the right part.  If I remember correctly, it was the wired battery.
Jodi


On Oct 13, 2021, at 10:24 AM, Michael Hamburg via groups.io <michael_hamburg44@...> wrote:


I truly love my AP900 GTO3 which I bought from the original owner a couple of years ago. However, I cannot get accurate GoTos no matter what I try. I use solely the had controller with the upgraded chip. I have synched, recalibrated, loosened  the clutches, issued GoTo commands, and retightened the clutches. I currently carry a Celestron Edge 11 HD with an Orion 80mm ED refractor piggybacked. The mount easily carries this set-up. So - is it 1) user error? 2) cone error (orthogonality?) 3) software bug? or 4) a nasty gremlin? Please help!

Michael HamburgEmoji


Scott Cooke
 

Would love to see a picture of the side by side setup.  I have thought of doing something similar with my 900.
Thanks,
Scott

On Thu, Oct 14, 2021 at 1:03 AM <weems@...> wrote:
My 900 carries a C14 and 6” f9 side by side and generally gets within 10’ of the target (closer to 7’ when not into refraction near the horizon).  And it can slew from one side of the meridian to the other then be told to return to the starting object, and will get it within 1’.  The planets are a bit off, probably because of clock drift, as I haven’t set it since the DST change.  But It wasn’t close to that until I did a draft alignment for 30 minutes in each axis, and adjusted cone error to less than 1’. It’s on a 12” concrete pier, with a very short rat cage. I replaced the flexible Celestron dovetail with a Losmandy. Every mechanical connection is also really tightened up.

Chip


Michael Hamburg
 

I wish it was that simple.
Michael

Best wishes, Michael


On Wednesday, October 13, 2021, 04:47:53 PM EDT, J. Belden via groups.io <jjb4469@...> wrote:


My main problems with bad gotos with any of my AP mounts has been wrong time, wrong date.
DST Non DST as well

Joe






Michael Hamburg
 

Fernando,
Not only did I loosen the clutches, but I then retightened them. This rig never moves out my observatory!
Michael

Best wishes, Michael


On Wednesday, October 13, 2021, 03:01:33 PM EDT, fernandorivera3 via groups.io <fernandorivera3@...> wrote:


You have loosened the clutches? Don't you mean "tightened down" the clutches?
Try checking your location data in the keypad. Is it accurate or way off like maybe you accidentally left it set on coordinates from a distant star party?
What about the clock time? Is it on standard time rather than daylight savings? Maybe it could be incorrect time zone setting. 

Fernando


fernandorivera3
 

Chip the ultimate method to get rid of flexure from your C14, beyond removing the cheap Celestron orange dovetail, is to mount the scope to a Andy Homeyer scope cradle- they are expensive but built like a tank. Absolutely rock solid.

Fernando


weems@...
 

My 900 carries a C14 and 6” f9 side by side and generally gets within 10’ of the target (closer to 7’ when not into refraction near the horizon).  And it can slew from one side of the meridian to the other then be told to return to the starting object, and will get it within 1’.  The planets are a bit off, probably because of clock drift, as I haven’t set it since the DST change.  But It wasn’t close to that until I did a draft alignment for 30 minutes in each axis, and adjusted cone error to less than 1’. It’s on a 12” concrete pier, with a very short rat cage. I replaced the flexible Celestron dovetail with a Losmandy. Every mechanical connection is also really tightened up.

Chip


Christopher Erickson
 

I configure ALL my mounts to use UT.

-Christopher Erickson
Observatory engineer
Waikoloa, HI 96738
www.summitkinetics.com
   

On Wed, Oct 13, 2021, 10:47 AM J. Belden via groups.io <jjb4469=yahoo.com@groups.io> wrote:
My main problems with bad gotos with any of my AP mounts has been wrong time, wrong date.
DST Non DST as well

Joe






J. Belden
 

My main problems with bad gotos with any of my AP mounts has been wrong time, wrong date.
DST Non DST as well

Joe


fernandorivera3
 

You have loosened the clutches? Don't you mean "tightened down" the clutches?
Try checking your location data in the keypad. Is it accurate or way off like maybe you accidentally left it set on coordinates from a distant star party?
What about the clock time? Is it on standard time rather than daylight savings? Maybe it could be incorrect time zone setting. 

Fernando


Howard Hedlund
 

Scroll down this page.    https://www.astro-physics.com/software-updates/


Mike Dodd
 

On 10/13/2021 12:27 PM, Christopher Erickson wrote:
Time to re-upload fresh code to the hand controller.
And to answer your "how hard" question, it's easy and straightforward. Download the database file from A-P, and follow the instructions in a document named dataload201.pdf. I don't know where to find it on the website, so maybe A-P can chime in.

--- mike


Michael Hamburg
 

Hi Christopher,
That's quite a list of culprits. Slight chance it could be #s 4 and 8. Definitely #11 is playing a big part. Pier goes down 9 feet and is filled with a lot of concrete.

Best wishes, Michael


On Wednesday, October 13, 2021, 12:22:57 PM EDT, Michael Hamburg via groups.io <michael_hamburg44@...> wrote:


PA is very good as evidenced by small corrections via PHD2.

Best wishes, Michael


On Wednesday, October 13, 2021, 12:11:20 PM EDT, Howard Hedlund <howard@...> wrote:


Keypad database corruption is generally catastrophic in terms of GoTos.  Database corruption sends you to the complete wrong place - not just *off-by-a-bit*.  And that's if you can slew to catalog objects at all.  

The number one reason by a HUGE margin for poor pointing is poor polar alignment.


Christopher Erickson
 

If the hand controller battery was replaced at some point then it is almost a certainty that the object database in the hand controller was corrupted by the bad battery, or got corrupted when the battery was replaced. Time to re-upload fresh code to the hand controller.

-Christopher Erickson
Observatory engineer
Waikoloa, HI 96738
www.summitkinetics.com
   

On Wed, Oct 13, 2021, 6:22 AM Michael Hamburg via groups.io <michael_hamburg44=yahoo.com@groups.io> wrote:
PA is very good as evidenced by small corrections via PHD2.

Best wishes, Michael


On Wednesday, October 13, 2021, 12:11:20 PM EDT, Howard Hedlund <howard@...> wrote:


Keypad database corruption is generally catastrophic in terms of GoTos.  Database corruption sends you to the complete wrong place - not just *off-by-a-bit*.  And that's if you can slew to catalog objects at all.  

The number one reason by a HUGE margin for poor pointing is poor polar alignment.