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Jkulin

AZ-EQ6-GT Mount miles off prior to plate solve

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Hi All,

Ever since I got my AZ-E6 last year it is always miles off when I first start from my target position.

Typically I start with the Dec and RA setup for for doing my PA using my polemaster (this is my home position) and then I start with a trial focus on Polaris to get things roughly in the right position and then I slew using Cartes du Ciel to my target, the problem is that I am always 5-6 degrees out until I have plate solved either with AT or Platesolve2.

I use EQMod with a direct connection to my laptop, I've cleared my alignment data and used it a few times since but always the same until plate solved, is there something I am missing in the settings to get it more accurate and even to keep the slew data to make it more accurate in future?

Thanks for your thoughts

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With Polemaster the mount doesn't need to be switched on, or even have an OTA fitted....  You just manually rotate in RA.

When PA is done, I set the mount to 'my' home position, i.e. weights down, OTA pointing in direction of Polaris.  I then switch on the mount, & connect CDC\EQMod etc. making sure that location\date time and settings are all correct in all places.

As I'm starting from the same position (my home position) all I need to do then is to un-park, slew to target, plate solve, and clouds permitting, I can start imaging.

For home, I've also built an eqmod alignment map, which automatically gets loaded on start up, this also aids in pointing accuracy. 

 

 

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Not great with statistics, or EQMod, but have you set your location correctly as I recall EQMod defaults to somewhere in Europe.

Also I always do a one star alignment near to my target and use that to do my focus.  Saves having to use Polaris every time.

Carole 

 

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Had the same problem but partly it was due to not lining up on my home position on the settings circles(weights down etc) and to be fair you can never be that accurate when aligning the pointers up afer your PA - IMHO.  Plus maybe you have caught the mount when adding your scope or camera - i do now and then.

As you are using EQMOD - Do you remember to "go to home position - i.e. PARK" before you close down your mount - only a suggestion  - as I bet you mostly do anyway.

Is you "kit" Balance out when fully loaded?

Changed any settings like JNOW to J2000 so that some software that controls the mount(via ASCOM) does not match EQMOD settings.

Did you have the mount powered up when using the Polemaster - my AZEQ6 and others have the secondary encoder feature -might cause a problem.

My workflow is :-

1. Power on all objects excluding the mount - just in  case of a "spike" causing the mount board problems.

2. Power on Mount.

3.  I use APT so I user Pointcraft to "goto" Polaris and let it Platesolve and then Sync - if its "light years" out I close down (as I probably have caught the scope - so moved the DEC/RA) and start with static weights down,Balancing etc set up - a pain but I don't do it very often(I should be more careful). Do my PA again without power to the mount - I use Sharpcap not Polemaster. Start from step 2 again.

4. Watch the clouds roll in :-)

Hope you get sorted

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Thanks for your replies.

@Dr_Ju_ju I always park/unpark my mount from it's home position, when I use my SA I have to manually move the mount for PA, but can't see the benefit of doing it manually when on the AZ.

@carastro Yes Carole my location lats and longs are set correctly in the parameters of EQ Mod.

My home position is Polaris so like you Carole I use that for focusing without having to move, I then slew to the target, plate solve as the stars are nice and reasonably sharp and then focus again.

I've never used a 1/2/3 star alignment, so would need to read up on that or as we do nowadays...youtube it :-)

I use the Polemaster and fire up the mount as it makes it easier to rotate using the EQmod controls rather than loosening the RA/Dec and manually moving when return to the home after following the green circle.

@stash_old I believed I had set my setting circles when first setting it up last year, but as I don't use the polarscope I never faffed around with anything other than setting the balance and alignment, am I missing something here? I always return to my zero setting circle positions after finishing each night. I'm moving away from APT although it is an excellent product, however its lack of equipment profiles makes it very frustrating so now use SGP 3 with platesolve 2

I have a permanent pier in the garden and all of my kit apart from the scopes and camera are easily to hand in a lean too at the side of my home, this includes all the 12v PSU with water proof connections and cables, , my workflow is: -

Power everything up and then launch Cartes du Ciel, Polemaster, phd2 and Sequence Generator.

Connect mount via EQmod in Cartes du Ciel

Connect all of the equipment is PHD2 and SGP 3

Polar align using the Polemaster software.

Focus on Polaris with a Bahtinov Mask

Slew to target using Cartes du Ciel, this is where it is miles out

Plate solve either with AT/APT (I used this until my confidence grew with SGP)

Commence imaging sequence with frame & focusing etc.

When occasionally I get problems with the plate solving, typically with the USB port doing a wobbly, then it would be good to know that as long as my polar alignment is good and everything else is fine that I shoudl be able to slew fairly accurately to the target.

Does the above make any sense?

Thanks once again.

 

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32 minutes ago, stash_old said:

Changed any settings like JNOW to J2000

For some bizarre reason I have found that once in a blue moon (metaphorically, not actually) CdC (running on an Intel NUC under Windows 10) seems to set itself back to JNOW from J2000 and that immediately manifests itself as my initial target being out by 4-5 degrees. Why this happens I have no idea - it just seems to happen without any intervention from me.

It's just one of the many random events that plague my imagining sessions - like SGPro suddenly no longer recognising my Atik camera until I reload the Atik Capture software. :confused4:

 

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1 hour ago, Dr_Ju_ju said:

For home, I've also built an eqmod alignment map, which automatically gets loaded on start up, this also aids in pointing accuracy. 

That sounds interesting, can you enlighten me?

5 minutes ago, Adreneline said:

For some bizarre reason I have found that once in a blue moon (metaphorically, not actually) CdC (running on an Intel NUC under Windows 10) seems to set itself back to JNOW from J2000 and that immediately manifests itself as my initial target being out by 4-5 degrees.

Thanks, I wonder, where can I check this setting?

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When you have everything connected, and can see stars, from within CDC\Stellarium, slew to a dozen known stars, in various parts of the sky, and when centred , press the Sync button. What this does is send a variance number to EQMod which it can use to build a pointing model giving better accuracy.

You find it in Alignment / Sync in EQMod

image.png.1ae75a4fdcfdf0a357816b6c2ace3660.png

 image.png.cbfe364dd1918f81d548d67c225997ea.png

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41 minutes ago, Jkulin said:

Thanks, I wonder, where can I check this setting?

5aa804d8212ec_Screenshot2018-03-1317_04_09.png.8d3563e251a9dccb646a6db852cea4d8.png

I find that it resets itself to 'Azimuthal' and 'Apparant' - not JNOW - sorry - and despite the fact the programme is set to 'save settings on exit'.

HTH

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@Adreneline Thanks, mine was set to the below as a default, what do these changes mean and what is the difference between J2000 and JNOW?

CdC_130318.PNG.3cfd45f2b040cd569d8b1e82eade53fd.PNG

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4 minutes ago, Jkulin said:

what do these changes mean and what is the difference between J2000 and JNOW?

Well I am sure I should know the answer to your question. All I know is that I select J2000 in EQMOD and in order to be consistent with CdC I need to select Equatorial Coordinates; once I've selected Equatorial I can choose J2000. I am sure I should understand exactly why it works but I'm afraid I don't! I presume CdC does not send the correct positional information to EQMOD unless it is set to Equatorial and J2000.

I'm sure someone will pop up and the answer your question and enlighten me at the same time!

Adrian

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Note that the EQMOD EPOCH setting doesn't affect/change EQMOD operation at all. In an ideal ASCOM world client applicaitons, like cdc, would connect to EQMOD, read the epoch, and then automatically adjust themselves accordingly.  In this way the user would only have to set the EPOCH in one place (the driver) and eveything else would follow suit. But in reality most clients don't do this and folks end up having to set them up manually in each and every client app.

Chris.

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3 hours ago, Jkulin said:

Polar align using the Polemaster software.

Are you sure that Polemaster software needs the mount to be switched on - moving the scope when its powered on will set the secondary encoders on certain mount

which will mean that your mount will be out but if you haven't got secondary encoders (allows manual movement in ra/dec) it may cause a problem- although it

should be ok for platesolving and goto's as I think the secondary encoders(if you have them) update EQMOD/CDC else there is a possible error.

When you say "miles out" - where do you get the info from and how many pixels does Platesolve say you are out

 after the first Platesolve match?

3 hours ago, Adreneline said:

For some bizarre reason I have found that once in a blue moon (metaphorically, not actually) CdC (running on an Intel NUC under Windows 10) seems to set itself back to JNOW from J2000

Yep I have found that - thought i was cracking up.

40 minutes ago, chrisshillito said:

most clients don't do this and folks end up having to set them up manually in each and every client app.

 

Its a pain to say the least - they dont even describe the settings in a manner for newbies to be able to know there are setting the same thing - e.g. CDC there is no JNOW tick box just a full blown techie description of JNOW

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Thanks Stash, to answer your questions: -

1. Its a while since I started using the polemaster and IIRC there was no mention of whether the mount should be switched on or not, however if you check any of the YouTube Videos they all have the mount switched on.

2. I'm normally swearing or was when it was miles out and never noticed what that recorded, but in CdC it looked approx. 5 -6 degrees out

If it goes clear tonight then will make a point of check it out to determine what it has reported.

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Posted (edited)
33 minutes ago, Jkulin said:

CdC it looked approx. 5 -6 degrees out

OK I think it sounds like the issue is the settings JNOW/J2000 etc issue - when I had a mix (APT ,CDC,EQMOD(even if it doesn't effect it)) then CDC would show me the scope position is being out even after a Platesolve that had worked and I had SYNC'd the object.

Check APT as he JNOW button is not very clear ,IMHO,  if its set or not so I have o click it just to make sure which way round it is - Please change this Yodha(APT Guru).

Chris Shillto is 100% correct all software should get the setting from one source - Mount driver IMO unless you are not using one.

It seems Polemaster does need the mount online "Don't manually perform the rotation by loosening the RA clutch as it will cause the rotational center to shift and result in large apparent error."

Good luck.

Edited by stash_old

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Thanks Stash, yep I was chatting to my mate this evening and he mentioned that he thought it might be that, by default it is set to EPOCH Unknown, would you suggest JNOW or J2000 and if so what is the difference.

Much appreciate everyone's help, thanks.

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7 hours ago, Jkulin said:

Thanks Stash, yep I was chatting to my mate this evening and he mentioned that he thought it might be that, by default it is set to EPOCH Unknown, would you suggest JNOW or J2000 and if so what is the difference.

Much appreciate everyone's help, thanks.

In my limited knowledge - basically its reference data and J2000 refers to "real" star atlases for where Celestrial Objects where in 2000(hence j2000)  - read this it sums the situation very well IMO http://www.astronomyforum.net/astro-imaging-forum/194029-confused-about-what-expects-j2000-coordinates-what-wants-jnow.html. I still find CDC description of what options you have confusing (mean or Astrometric j2000 ? - ok mean is average etc :dontknow:) and as far as I understand Jnow vs j2000 give 1 arc min(?) difference(and changes over time) but obviously "fast" objects will be more and they are talking about creating J2050(Madness but I wont be here then).

So JNOW is more accurate but j2000 is supported more I guess - i would settle for a simple tick box j2000 or Jnow !!!.  Maybe an expert will enlighten us. Glad you got sorted - clear skies.

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I have also experienced problems with pointing accuracy with CdC and EQmod running my tuned NEQ6  and  would like to thank you for highlighting some settings in CdC that I hadn't checked previously. I have just altered some of the settings and resynced some of my previous alignment points. I am hoping that next time the pointing will be more accurate but I will recheck the settings anyway. 

Having read one comment about CdC not saving settings on exit despite the box being checked I chose "save configuration now" as a precaution even though I also had checked the save on exit box. Anyway thanks again to everyone - here's hoping it will solve my pointing accuracy problem.

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I'm using CdC (V4.1.1) with EQMod (V2.6) on my NEQ6pro mount to control my C11 (at f10) for spectroscopy.

If the Park position is accurately set-up GOTO's work very well, Syncing as I go, the results as verified by Astrometry.net are very good.

Astrometry.net returns results in the astrometric frame of the reference catalog, and the 4100- (Tycho-2) and 4200- (2MASS) series index files are both in  J2000.0

 

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I've sold the AZ-EQ6-GT now and am waiting on delivery of my new iOptron CEM60EC, it will be interesting to see how that performs in comparison.

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