Problem finding target - I'm baffled! EQ8 mount perhaps?

[Gina]

I've got a lovely clear sky and two imaging systems working trying to set up on the Pacman for some more Ha and OIII data.  BUT I seem to be having a problem with the EQ8 mount.  I set CdC and EQMOD ASCOM to park to the Home position and roughly aligned the scope to point to the pole.  Then I slewed to the moon but it was several degrees off.  So I did what I always do - realign the mount onto the moon using my finder scope with the clutches slightly released.  And yes, moon nicely centred in both imaging frames.  BUT (again) CdC now shows the imaging frame several frame widths away from the moon yet I havent touched CdC and the tracking is set to Lunar.

I have tried to get AstroTortilla to plate solve and slew to the Pacman using an image from the other night.  That image solved fine and the scope ended up pointing in approximately the right direction.  But when I tried to plate solve an image from the Esprit (the scope I use for setting up) AT wouldn't solve - not even with the coverage set to 180 degrees and using 15s binned 8x8 (I usually plate solve with 10s and 8x8 which has worked fine).  I'm getting over 200 stars to plate solve on which should be more than enough.  But it just won't.

I'm baffled - anyone any ideas please?

[iksose7]

Once you had the Moon centered, hit the sync button in CdC and your target frame in the planetarium will be where is should be.

You say your search radius in AT is 180º?! That is way too high and maybe why its not solving. I have mine set to 15. If that doesnt work you could also try de-focusing a little as i have found AT struggles sometimes with accurate focus.

All i usually do nowadays is power the mount up, polar align, de-lock clutches, point the scope roughly at the right patch of sky, lock clutches, run AT, done. Takes 10 minutes max if everything goes right!

Hope this helps

Callum

[kirkster501]

My workflow is slightly different Gina.

1. Start from home position.  Does not actually matter being spot on just point the scope on the mount roughly north  Now resync EQmod motors and tell it that is the home position.

2. Slew to first bright star.  You will probably be a few degrees off because your home position in step 1 was not precise.  However, there will almost certainly be some stars to get a rough focus in step 3.  I have never known there not to be

3. Get rough focus "manually" by looping one sec exposures from where the mount ended up in step 2 on whatever stars you find.  When focused "roughly" plate solve.

4. Mount now moves to exact position that CdC thinks it should be in, i.e on the bright star you asked the mount to slew to in step 2.

5.  Now loop your exposure and with whatever method you use to achieve fine focus - Bahtinov mask in my case.

[Phillyo]

Gina,

If I'm reading you right you're saying you slew to your target and it's not centered...so you release clutches and centre it yes? I'm only very new to astro stuff but surely by releasing the clutches you're defeating the object? Without the clutches engaged you could move the scope upside down and the mount would still think it's pointing where it was before you released the clutches? I could be wrong though!!!

What I normally do is polar align using EQMod, focus on polaris so it's pretty close (doesn't need to be perfect) then I slew to my target. I use pinpoint for plate solving but AT would work the same, I then plate solve and the mount auto syncs and moves to where it should be. This will update the pointing model in EQmod telling it how far out it was.

If you want to be very accurate you should really point to a number of stars in different areas of the sky, plate solve, reslew and sync so that it builds up a better model.

If you're solving with a different scope and it's not working, have you entered all the details into AT correctly for the new scope? FoV? Correct catalogues downloaded etc?

Phil

[Tinker1947]

Could be a complete reboot might sort it out.......

[Tim]

No idea about your particular problem Gina, but don't waste a clear night, can't you just get the RA and DEC and manually slew there ?

[Thalestris24]

I think the max search radius for AT is 45 deg. - I'm sure I read that on their forum or somewhere. If you get a very large number of stars you can try increasing the --sigma value. I think AT can get overwhelmed. I've also had problems with it not solving sometimes when it's already spot on. 

Hth

Louise

[Gina]

Thanks for all your replies   I'll reply shortly.

I found my target by roaming round the sky in the vicinity, adjusted it to the centre of the frame and set up PHD guiding.  Then started capturing data in Ha and OIII with the ST80 and Esprit respectively.  5m subs binned 2x2.  The seeing doesn't seem quite as good tonight as the other night though.

CdC was showing the imaging frame way off the mark.

After capturing data for an hour or so a meridian flip was due so I used AT on an earlier sub to do that and it solved fine.  But again it wouldn't solve on the shorter exposures with 8x8 binning.  Anyway, I slewed to M31 and that came in the frame to one side so I centred it and noted the offset in CdC.  Slewed back to the Pacman and applied the offset.  The Pacman then appeared in the frame and I could centre it. Set up guiding and continued capturing data.  The view in CdC now shows the object in the imaging frame

[Zakalwe]

Don't forget that the EQ8 has encoders!

Opening the clutches and manually moving it does nothing, as it just reads the new position from the encoder.  Delete all your alignment points in EQMOD, slew to a known star, centre it and then hit Synch in Cdc. Job jobbed.

Or get SGPro and let it plate-solve, centre and synch automatically.

[Gina]

Once you had the Moon centered, hit the sync button in CdC and your target frame in the planetarium will be where is should be.

You say your search radius in AT is 180º?! That is way too high and maybe why its not solving. I have mine set to 15. If that doesnt work you could also try de-focusing a little as i have found AT struggles sometimes with accurate focus.

All i usually do nowadays is power the mount up, polar align, de-lock clutches, point the scope roughly at the right patch of sky, lock clutches, run AT, done. Takes 10 minutes max if everything goes right!

Hope this helps

Callum

Thank you Callum - yes I think it does    Re. Sync button - I still have lots to learn

As for the search radious, I generally use 45º but if I think I may be a long way out I set it to 180º and that sometimes works   Didn't know about de-focussing for AT

Your procedure is very interesting - much quicker than mine - I'll try that - thank you

[Gina]

Once you had the Moon centered, hit the sync button in CdC and your target frame in the planetarium will be where is should be.

You say your search radius in AT is 180º?! That is way too high and maybe why its not solving. I have mine set to 15. If that doesnt work you could also try de-focusing a little as i have found AT struggles sometimes with accurate focus.

All i usually do nowadays is power the mount up, polar align, de-lock clutches, point the

[Gina]

My workflow is slightly different Gina.

1. Start from home position.  Does not actually matter being spot on just point the scope on the mount roughly north  Now resync EQmod motors and tell it that is the home position.

2. Slew to first bright star.  You will probably be a few degrees off because your home position in step 1 was not precise.  However, there will almost certainly be some stars to get a rough focus in step 3.  I have never known there not to be

3. Get rough focus "manually" by looping one sec exposures from where the mount ended up in step 2 on whatever stars you find.  When focused "roughly" plate solve.

4. Mount now moves to exact position that CdC thinks it should be in, i.e on the bright star you asked the mount to slew to in step 2.

5.  Now loop your exposure and with whatever method you use to achieve fine focus - Bahtinov mask in my case.

Thank you Steve   I use FWHM in Artemis Capture to refine my focus.

[Ant]

I thought that the EQ8 had decoders on both axis? If thats the case moving the mount manually will move the scope in CdC.

I'd get the moon in the FOV and then Sync on it in CdC, should be straight forward after that?

I know this post is a little late as its now daylight, but did you get there in the end?

Ant

[Zakalwe]

I thought that the EQ8 had decoders on both axis? If thats the case moving the mount manually will move the scope in CdC.

I'd get the moon in the FOV and then Sync on it in CdC, should be straight forward after that?

It's best to delete all alignment points in EQMOD first, otherwise it might build a wonky alignment map. But, yes, opening the clutches and moving it won't fix the problem as the encoders will just update EQMOD & CdC.

"Freedom-Find™ Technology

A great feature of the EQ8 is the patented dual-encoder technology. Auxiliary encoders are located on both the R.A. and DEC. axes. This allows the telescope to be moved manually, by releasing the clutches, or electronically in either axis without the mount losing its alignment or positional information. After moving to a new object, the mount will continue to track it accurately. This gives the user enormous freedom, convenience and flexibility during observational sessions."

[StuartJPP]

That is why I like the AstroTrac...point and shoot

Hope you get it sorted for the next outing.

[Thalestris24]

Hi Gina

Just a thought, I've had problems in the past using AT with eqmod syncs - they seemed to clash, I think. It may have just been me or a Stellarium bug - it was earlier on in the year. Anyway, a way round it was to set eqmod to 'dialog based' rather than 'sync based'. Dunno if that has any bearings on your recent problems but thought I'd mention it.

Louise

[Gina]

Thank you Louise

[lensman57]

Wouldn't the encoders report the position of the mount to CDC through EQMOD? Can the encoders be disabled until you are centred and then reengaged?

Regards,

A.G

[Gina]

I should think so but I don't know.  Anyway, I have everything working again now so I don't know what the trouble was.  I expect I got something wrong just don't know what.

[NickK]

Atmospheric refraction? If you sync to a star low down and the system isn't taking into account the change in refraction it could explain why..

[Gina]

Not in this case - DSO was almost overhead.  Thanks for the suggestion though