How do I get a target after achieveing Polar Alignment

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CarlGreen
Posts: 23
Joined: Sat Feb 13, 2021 9:06 am

How do I get a target after achieveing Polar Alignment

#1

Post by CarlGreen »

Hello everyone, I am hoping someone can help (or point me in the direction of Tutorials specific to this question as I can't seem to find any?)
A Bit Of Background.......
(EQ8 Mount, Using GS Server)
After a long time, (And I mean long!) I have finally got Sharpcap talking to my equipment and managed to set up a Polar Alignment using Sharpcaps excellent feature. (The long time relates to my ignorance, not Sharpcaps programming!)
I am going to list my workflow below so that someone can spot where I am going wrong (Other than I should have taken up Golf instead!) and Correct me.

After getting either a good or excellent polar alignment, I return the mount to the "Home" position (Scope on top of mount pointing northwards, Counter weights down.....) And do a Plate Solve only. I then go to Tools on the Sharpcap interface, Select GoTo Catalogue Target Coordinates and select "Goto a target from the catalogue" I then put in my target (In this instance it was Jupiter) I then clicked start, it then started its procedure and moved my mount, however, it moved it to approx 90 degrees East of where Jupiter was (Not exactly sure of how out it was, but looked about 90 degrees, I could see Jupiter Westerly of my position!). My location position is correct in my GS Server (The Ascomy bit that communicates with Sharpcap, can you guess yet that I'm not all that Au Fait with all this stuff :) ) and I end up pointing to somewhere I did not want to be!

So what am I missing here?

Any help appreciated

Thanks
Celestron 9.25 - Altair 155 f8
GoTo Evolution Alt-Az Mount - Eq8
Starsense Explorer
Celestron Focus Motor
QHY5iii462C / Skyris 132M / ZWO ASI294MC Pro
Celestron f6.3 Focal Reducer
Windows 10 Home Edition
I5 - 825OU CPU - 180 Ghz, 8GB RAM
CarlGreen
Posts: 23
Joined: Sat Feb 13, 2021 9:06 am

Re: How do I get a target after achieveing Polar Alignment

#2

Post by CarlGreen »

Hi Folks, just clarifying my above post........other than doing a polar alignment, I have done nothing else.

(Equipment = EQ8 Mount connected in Sharpcap by GS Server, Latest Sharpcap Software)

Should I do a Star alignment with the Mounts Hand Controller? (I have never done this, I (stupidly) thought that doing a Polar Alignment was all that was needed.

And do I do a Polar Alignment in Sharpcap First, then a Handset Star Alignment then back to Sharpcap for Go To's?
If this IS the case, should my workflow be.......
Do Polar Alignment in Sharpcap
Do a plate solve in Sharpcap
Initialize hand controller (Will the Hand Controller work whilst Sharpcap is still connected to the mount?)
Do its Star Alignment routine (Either the 1, 2 or 3 depending on seeing)
Go back to Sharpcap and re poition Scope to Home Position (Pointing north and weights down)
Slew to a part of the sky with stars and do a Plate Solve,
Then use the tools/goto catalogue target. select a target and press start (Then hopefully it should slew to the chosen target)
Once there and centered how I want it, do I do another plate solve?


Sorry if these seem basic questions but I have tried to find tutorials online but to no avail, there seems to be plenty of info on Either Polar Aligning OR Star Aligning but not how they combine and.......

Thanks for any help
Celestron 9.25 - Altair 155 f8
GoTo Evolution Alt-Az Mount - Eq8
Starsense Explorer
Celestron Focus Motor
QHY5iii462C / Skyris 132M / ZWO ASI294MC Pro
Celestron f6.3 Focal Reducer
Windows 10 Home Edition
I5 - 825OU CPU - 180 Ghz, 8GB RAM
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Re: How do I get a target after achieveing Polar Alignment

#3

Post by admin »

Hi,

a lot depends on how you use your equipment apart from using it with GSS... If you only use the equipment with GSS then GSS should remember the position of the mount when it was last used, and providing when you start the next time it is still physically in the same position, GSS should pick up automatically with no need to star align using the handset. Even if you use it with the handset, but always get it back to the same position then GSS should cope.

The problems happen when the mount is physically in a different position to the one that GSS has remembered the last time - GSS will think it is in the home position with scope up and weights down, but actually it is rotated from that position with the counterweight bar horizontal. If that happens then every GOTO movement will be wrong. In that case you need to do something to put the mount back into the position that GSS thinks it is in - that could include

* Star aligning with the handset
* Using the plate solve + sync button in SharpCap to resynchronize (note - by default, will only work with up to a 15 degree offset)
* Unlocking the clutches and moving the axes to make the scope really point at the target GSS thinks it is pointing at (followed by plate solve and sync)

You should also check that GSS has the correct info for latitude, longitude and time before any of this - if those are wrong then the telescope will point to the wrong place because of that error.

cheers,

Robin
CarlGreen
Posts: 23
Joined: Sat Feb 13, 2021 9:06 am

Re: How do I get a target after achieveing Polar Alignment

#4

Post by CarlGreen »

admin wrote: Mon Apr 01, 2024 1:14 pm Hi,

a lot depends on how you use your equipment apart from using it with GSS... If you only use the equipment with GSS then GSS should remember the position of the mount when it was last used, and providing when you start the next time it is still physically in the same position, GSS should pick up automatically with no need to star align using the handset. Even if you use it with the handset, but always get it back to the same position then GSS should cope.

The problems happen when the mount is physically in a different position to the one that GSS has remembered the last time - GSS will think it is in the home position with scope up and weights down, but actually it is rotated from that position with the counterweight bar horizontal. If that happens then every GOTO movement will be wrong. In that case you need to do something to put the mount back into the position that GSS thinks it is in - that could include

* Star aligning with the handset
* Using the plate solve + sync button in SharpCap to resynchronize (note - by default, will only work with up to a 15 degree offset)
* Unlocking the clutches and moving the axes to make the scope really point at the target GSS thinks it is pointing at (followed by plate solve and sync)

You should also check that GSS has the correct info for latitude, longitude and time before any of this - if those are wrong then the telescope will point to the wrong place because of that error.

cheers,

Robin
Hi Robin
This is what I do.......doing this from memory so bear with me.......
My set up is kept in my garage and I lump it outside when I am doing a session.
I put it close (but not exact!) in the position I always put it in and then carefully (Physically) point the mount counter weights towards North, and the Telescope on top of the mount pointing towards Polaris. (This is what I call the Home position - Very nearly Polar Aligned but not quite there...)
I then go through a Polar Alignment using Sharpcap and once achieved alignment and locked everything down, I do a plate solve, I then return the scope (by the scope controls) to my "Home Position" I then choose a target from the tools/catalogue secion and click start.

This is where it seems to go awry....I have never yet managed to get my scope to point towards where my target is (I dont expect to be able to see it without a bit of tweaking, but my scope is pointing so far away from where it should be that something has definitely gone wrong!).

What am I missing (As far as I can tell the GS Server has the correct coordinates (Latitude and Longitude) and the time is taken from my laptop (which shows the correct time)

I have tried several times and can't get beyond this issue.........I must be missing something obvious to seasoned Astrophotographers! - I have not done a star alignment via the handset, could that be my problem? (I realise how difficult it is to give a definitive answer to any of this but appreciate your pointers)

Sorry if these seem a bit basic questions, but believe me for me this is like the Everest of learning! :)

Thanks
Celestron 9.25 - Altair 155 f8
GoTo Evolution Alt-Az Mount - Eq8
Starsense Explorer
Celestron Focus Motor
QHY5iii462C / Skyris 132M / ZWO ASI294MC Pro
Celestron f6.3 Focal Reducer
Windows 10 Home Edition
I5 - 825OU CPU - 180 Ghz, 8GB RAM
kaymann
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Re: How do I get a target after achieveing Polar Alignment

#5

Post by kaymann »

(This is what I call the Home position - Very nearly Polar Aligned but not quite there...)

Home position in astro speak has nothing to do with polar alignment... When we say home position this is when we hit the home command and then the scope/mount moves the predetermined "home" position. For most of us that is the storage position - counterweight shaft vertical down (to visualize this if there were no scope on the mount the weight would pull the shaft to the home position). Also the mounting plate would be centered vertically, (to visualize this if you put a weight on the lower end of the mounting plate it would swing the mounting plate to the home position). We typically make sure the scope is in the home position using the clutches or by hitting the home "Button" and the end of the previous session, before we begin any Polar Alignment (PA).

I then go through a Polar Alignment using Sharpcap and once achieved alignment and locked everything down, I do a plate solve, I then return the scope (by the scope controls) to my "Home Position" I then choose a target from the tools/catalogue section and click start.

Try PA, then go to the Home Position with the Home button (one click home position button - no clutches), then find a nonpolar star near your target to plate solve. Plate solving near the pole does not usually give me very accurate results.

I hope this is helpful and not in any way disrespectful.

Randall
CarlGreen
Posts: 23
Joined: Sat Feb 13, 2021 9:06 am

Re: How do I get a target after achieveing Polar Alignment

#6

Post by CarlGreen »

I hope this is helpful and not in any way disrespectful.

Randall
[/quote]

Thanks Randall, it is DEFINITELY NOT disrespectful! I welcome any tips and advice to help me along with this bloody hobby! :)
Celestron 9.25 - Altair 155 f8
GoTo Evolution Alt-Az Mount - Eq8
Starsense Explorer
Celestron Focus Motor
QHY5iii462C / Skyris 132M / ZWO ASI294MC Pro
Celestron f6.3 Focal Reducer
Windows 10 Home Edition
I5 - 825OU CPU - 180 Ghz, 8GB RAM
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Re: How do I get a target after achieveing Polar Alignment

#7

Post by admin »

Hi,

yes, it does certainly sound as though once you have done the polar alignment the mount control software (GSS) is confused about the position that the telescope is pointing to. The software can only really measure *relative* movements of the mount , so if its initial data on the absolute position is wrong, everything will be wrong after that until you teach it the right position.

As Randall said, pressing the 'Home' position button is a good test - it should move the mount to the 'weights down, scope up, pointing north' position. If it goes anywhere else then GSS has the wrong initial position and that will be the cause of the problems. The simplest fix is to press the 'Home' button, wait for it to move to the wrong position, then unlock clutches and manually turn to the correct home position, then lock clutches and proceed with (hopefully) correct operation.

cheers,

Robin
CarlGreen
Posts: 23
Joined: Sat Feb 13, 2021 9:06 am

Re: How do I get a target after achieveing Polar Alignment

#8

Post by CarlGreen »

Thanks :)
Celestron 9.25 - Altair 155 f8
GoTo Evolution Alt-Az Mount - Eq8
Starsense Explorer
Celestron Focus Motor
QHY5iii462C / Skyris 132M / ZWO ASI294MC Pro
Celestron f6.3 Focal Reducer
Windows 10 Home Edition
I5 - 825OU CPU - 180 Ghz, 8GB RAM
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