Strange Goto's

[malc-c]

Having spent an hour leveling the pier adapter, the polar aligning using EQMOD's utility, and then setting the home position up with levels, I cleared all points in EQMOD and started again.

1st point - Vega. Alignment was slightly off so I tried the suggestion of undoing clutches and manually locking on the star using an 8mm eyepiece (125x in the 200P) - sync added

2nd point - Altair. Alignment was close, used gamepad to align and sync

3rd point - Mizar. Again alignment was off slightly in the eyepiece FOV. Gampad used to center star and sync point added.

Selected M31 as a test target, used a low power 32mm eyepiece, slewed and bingo the galaxy was bang in the centre of the FOV.

I then selected M45, and then slewed back to Vega so I could attach the dslr camera and use the mask to focus. Vega was way off (approx half the radius of the finder's FOV.) - Clutches were locked solid so I don't think that was the issue

With the camera attached I tried some drift alignment using the DARV method and the traces were spot on with no adjustment of the AZ / alt bolts required.

Comments please - as this is doing my head in !!

[izakimak]

What's mount you using?

I have a skywatcher eq6 with synscan.

Had loads of goto aiming problems last night.

After 2 alignment calibrations it still missed m31, m45 and m42.

Gave up not long after that (ill at the present time).

[steelfixer]

Hi Malcolm

What are you using for the goto commands.

Eqmod via a planitarium programe or the handset.

If you set up the polar alignment with Eqmod and are using Eqmod for the goto then I think you messed up the polar alignment when you undid the clutches on the first star.

Try aligning all the stars with the gamepad and syncing

Mind I could be wrong but I would give it ago.

I have also found that backlash in the mount will give you the same problem.

[Zakalwe]

Why open the clutches? Won't that cause EQMod to lose the alignment?

Also, there's no need to spend ages levelling the pier head....the act of polar aligning is all that is needed.

[malc-c]

Thanks for the replies guys.

To answer some of the questions:

1) - The mount is an HEQ5 pro, permanently mounted on a pier adapter in an observatory. The adapter is as level as can be made using a bubble spirit level in all directions.

2) - Polar alignment was undertaken as per the EQMOD alignment video on YouTube. IE centre Polaris on the cross-hair in the polarscope, then used the alt bolts to move it left to the 9 O'clock position (as this was closest to where Polaris HA was on the utility). Select 9 O'clock in the EQMOD utility and it the button to move the scope. Then used the Alt/Az bolts to place Polaris centrally in the circle on the ring. Released the clutches and rotated the mount slowly whilst viewing through the polar scope to ensure that Polaris tracked round the ring (which it did). With the clutches released I used EQMOD to park the scope in the home position, then places the scope in the home position (I have marked the mount to aid this) and then locked the clutches.

3) - I use CdC and EQMOD to navigate to targets. I selected Vega, right click, slew. I have in the past used the gamepad to correct the position, but following a suggestion from a person on this forum, released the clutches and manually placed the target in the FOV. I often find that when using the gamepad, the scope position displayed in CdC is off the target by the amount the scope has been moved. Either way I then add a sync point.

4) - I use a GPS dongle to set EQMOD to the correct latitude, time etc. I also use a tool to sync the PC to the same time via the same GPS dongle. CdC has been set up using the long/lat/height etc from the GPS dongle, so all apps are set as close as possible to the same settings, and as accurately as possible within the tolerances if the GPS dongle

5) - I use an EQDIRECT cable to connect the PC to the mount. I do have a handset and I'm going to try using that next session, and repeat the three star alignment using the same targets, and the slew back to Vega to see if it re=centres Vega back in the FOV of the eyepiece. If it does and I get near perfect goto's with the handset then that would rule out backlash as suggested. Whilst I know backlash can be a problem, it would have to be excessive to cause the slewing to be this far out IMO. I'm hoping that it's not a clutch problem that's the cause. The scope has been balanced in all directions following Astronomyshed's excellent video. Again the handset would settle any clutch-slip etc as the casue, which would leave CdC or EQMOD as the possible cause for the missed go-to's ??

[Zakalwe]

Thanks for the replies guys.

To answer some of the questions:

1) - The mount is an HEQ5 pro, permanently mounted on a pier adapter in an observatory. The adapter is as level as can be made using a bubble spirit level in all directions.

2) - Polar alignment was undertaken as per the EQMOD alignment video on YouTube. IE centre Polaris on the cross-hair in the polarscope, then used the alt bolts to move it left to the 9 O'clock position (as this was closest to where Polaris HA was on the utility). Select 9 O'clock in the EQMOD utility and it the button to move the scope. Then used the Alt/Az bolts to place Polaris centrally in the circle on the ring. Released the clutches and rotated the mount slowly whilst viewing through the polar scope to ensure that Polaris tracked round the ring (which it did). With the clutches released I used EQMOD to park the scope in the home position, then places the scope in the home position (I have marked the mount to aid this) and then locked the clutches.

3) - I use CdC and EQMOD to navigate to targets. I selected Vega, right click, slew. I have in the past used the gamepad to correct the position, but following a suggestion from a person on this forum, released the clutches and manually placed the target in the FOV. I often find that when using the gamepad, the scope position displayed in CdC is off the target by the amount the scope has been moved. Either way I then add a sync point.?

OK, levelling the pier head is not important.

polar align using EQmod or Alignmaster (if you have it). Go into CdC and connect to the mount (go to the menu bar > Telescope>Control panel and select Configure. It should pick up EQMod. Then click on connect at the bottom. This connects CdC via Ascom to the mount.

Then, using a game-pad (or EQmods direction keys) slew the telescope to a suitable star (use the finderscope). Once the star is centred in the telescope FOV (either in the CCD or EP) go to CdC and select the same star. Right click on the star and select Telescope in the pop-up menu, which will then pop up another menu. Select "Sync". CdC will then ask you to make sure that the star is centred, click on OK and this aligns CdC and EQMod to the star. You can then select other stars to improve on the accuracy.

To be honest, I only select a star near the area that I am interested in. If you want to go somewhere else, then select that object in Cdc, right click on it and select Telescope and Slew. CdC will the issue commands to slew to that object. If the alignment is a bit off, then move the scope using the EQMod direction keys or gamepad, then right click on the object in CdC, selct Telescope and Sync again.

Once you have done the first Sync command if you open the clutches and move the scope manually you will have lost the alignment in EQMod and in CdC!!!!!

[malc-c]

OK, levelling the pier head is not important.

polar align using EQmod or Alignmaster (if you have it). Go into CdC and connect to the mount (go to the menu bar > Telescope>Control panel and select Configure. It should pick up EQMod. Then click on connect at the bottom. This connects CdC via Ascom to the mount.

Is this any different to launching EQMOD first and then CdC, selecting Telescope and then clicking on the connect button ?

Then, using a game-pad (or EQmods direction keys) slew the telescope to a suitable star (use the finderscope). Once the star is centred in the telescope FOV (either in the CCD or EP) go to CdC and select the same star. Right click on the star and select Telescope in the pop-up menu, which will then pop up another menu. Select "Sync". CdC will then ask you to make sure that the star is centred, click on OK and this aligns CdC and EQMod to the star. You can then select other stars to improve on the accuracy.

Again, what's the difference between selecting the star in CdC, slewing, centreing and then syncing.

To be honest, I only select a star near the area that I am interested in. If you want to go somewhere else, then select that object in Cdc, right click on it and select Telescope and Slew. CdC will the issue commands to slew to that object. If the alignment is a bit off, then move the scope using the EQMod direction keys or gamepad, then right click on the object in CdC, selct Telescope and Sync again.

Agreed, the last sentence outlines exactly the procedure I follow

Once you have done the first Sync command if you open the clutches and move the scope manually you will have lost the alignment in EQMod and in CdC!!!!!

Which is possible where I went wrong

[Merlin66]

I start from a EQMOD "park" position then straight into CdC for slew and sync....

I find the more (distributed) sync's I do with CdC to easier it becomes......

[malc-c]

Ok I know the HEQ5 doesn't have optical encoders so has no real idea where it's pointing, but does CdC take it's positioning from EQMOD, or is it the other way around ?

[Merlin66]

Assume for the puposes of the exercise that CdC gets the same info as the EQMOD....

Any "sync" clicked in CdC is recorded by the EQMOD model.....

[Zakalwe]

Is this any different to launching EQMOD first and then CdC, selecting Telescope and then clicking on the connect button ?

That's what I do. More specifically, I launch EQASCOM, make sure the correct COM port is selected in Driver Setup, hit Test Connect which then launches EQMod. Once EQMod is controlling the scope i then launch CdC and connect to the mount (technically speaking, CdC is connecting to ASCOM which then passes the information to EQMod and the mount).

Is this any different to launching EQMOD first and then CdC, selecting Telescope and then clicking on the connect button ?

Again, what's the difference between selecting the star in CdC, slewing, centreing and then syncing.

Agreed, the last sentence outlines exactly the procedure I follow

Whats the difference? My method works and yours doesn't.

Why do it that way? Until you align the mount position with CdC the program has no understanding of where the mount is pointing (I am assuming that you are starting from an unknown first position. If you are using the pier correctly you should "park" the mount at the end of your session. Then the mount is in a "known" position the next time you connect to it). Slew the scope manually (using the gamepad or direction keys) ans centre the scope on a known star. Then tell CdC to select the same star (by clicking on it- do not issue any commands). Now you have the mount and CdC all pointing at the same object. Issuing a sync command tells CdC (via ASCOM) to read out the position on the mount encoders and to use that as the location of the know star.

Which is possible where I went wrong

Once you open the clutches and manually move the scope you lose the synchronisation between mount and EQMod/CdC, as the encoder do not move with the scope (they only move when the clutches are engaged. If you move the scope in this way you will have to re-synchronise the mount and CdC again.

[malc-c]

Whats the difference? My method works and yours doesn't.

Why do it that way? Until you align the mount position with CdC the program has no understanding of where the mount is pointing (I am assuming that you are starting from an unknown first position.

I have a custom park position which is used to store the scope, and also have a "corrected home" position where the scope is in the standard home position where everything is squared off.

If you are using the pier correctly you should "park" the mount at the end of your session. Then the mount is in a "known" position the next time you connect to it). Slew the scope manually (using the gamepad or direction keys) ans centre the scope on a known star. Then tell CdC to select the same star (by clicking on it- do not issue any commands). Now you have the mount and CdC all pointing at the same object. Issuing a sync command tells CdC (via ASCOM) to read out the position on the mount encoders and to use that as the location of the know star.

Once you open the clutches and manually move the scope you lose the synchronisation between mount and EQMod/CdC, as the encoder do not move with the scope (they only move when the clutches are engaged. If you move the scope in this way you will have to re-synchronise the mount and CdC again.

I think what's happened is somewhere alone the line is this synchronization has slipped, in that whilst the scope is set in the home position, EQMOD is thinking that the mount is slightly off. It will be the weekend before I get chance to look at the settings again and run through the procedure to re-sync the mount and try your suggestion