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Attempted First Light Last Night - Need Help

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#1 ESzczesniak

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Posted 05 July 2020 - 10:17 AM

I am very new to astronomy, as many of you may be guessing after I've already posted a handful of topics.  I started visual astronomy about 3 months ago and tried my first actual night session with a DSO AP last night.  Based on what I was planning to accomplish, I can't say it was a complete failure, but I need help/input. The AP setup I have is:

 

1. WO Zenithstar 81 mm

2. WO 50 mm guidescope

3. ASI 290MM guide camera

4. ASI 294MC-P Imaging Camera

5. EQ6-R Mount

 

And software:

 

1. SharpCap

2. CdC

3. PHD2

4. AstroTortilla

5. Necessary ASCOM/EQMOD drivers

 

I've spend the last month or so reading and setting up all the software and hardware as far as I can.  During the day when there's nothing to see through the camera, all interfaces seem to work well. 

 

Last night I attempted a practical session.  Yes, the 4th of July with a full moon is a poor night, but I wasn't planning to actually image anything.  My goals were:

 

1. Polar Align

2. Goto align the scope

3. Guide on a star

 

Not surprising, I ran in to some troubles and was hoping this is where I could find some help.

 

1. Success! - I used the SharpCap PA tool and by their numbers, had to 2-2.5 arc minutes of accuracy.  I know it'll need to be better, but since I wasn't planning on actually imaging, stopped fiddling a bit early.  The SharpCap PA tool is a plate solver, so I also proved on the main scope that I could focus (rough, then using the SharpCap FHWM tool) and adjust gain/exposure to get a good star field. 

 

2. Failure - This is where my real struggles were and I'm hoping for help.  I set the home position of my scope a while ago, trying to be very careful, based on this link: https://www.myastros...om/homeposition .  After PA, I shut down the scope and software, returned the DEC and RA clutches to zero and locked them.  Then powered the scope and software back up.  I then loaded CdC, connected the scope, and slewed to the target.  In SharpCap on the scope control, I selected solve and sync and it failed.  I then used the plate solve under tools and it did successfully solve a plate providing my RA/DEC.  The point it solved was only about 0.5 degrees off DEC, but about 1:40 off RA.  Not sure why.  That's one place I'm hoping people could help with.  Perhaps I had mismatched Epochs?  Not sure if the error is this big or not.  Anyway, I tried to troubleshoot, I unlocked the RA clutch, rotated the roughly 1:40 and locked it again.  Through the plate solve tool I was now about 0.5 degree on DEC again, and RA was about 00:01:15 off the reported scope position.  So I tried solve and sync again...and failed again. 

 

Now complicating this, I didn't realize my date, time, or location in CdC was clearly off.  It didn't register to me at first.  The target selected was M31 showing about 40 degrees of altitude in CdC.  Seemed a little fishy since I haven't seen it until about 3:30 AM visually and it's a known fall targer, but again it didn't register at the time.  Would this affect the solve and sync thought?  It seems to me that it is just trying to match plate solve coordinates to where the telescope thinks it is pointing.  So even if M31 wasn't at DEC 39.6 and RA 00:45:??, something is and it'll solve those coordinates?  And it did plate solve just fine from tools, just not the "solve and sync".  But perhaps time did enter somewhere here in the equation.

 

3. Failure - I couldn't get any starts to show up here.  I am sure the lens cap was off.  Most of my experimenting was with about a 2 second exposure and gain around 200.  I think the issue was focus.  I had tried focusing on a distant daytime object.  But as I found with main scope, the infinity focus can be a long way off a 300 meter terrestial focus.  This is the guide scope: https://williamoptic...h-1-25-rotolock . The focus is simply by sliding the eyepiece or camera along the visual back, then locking it.  I think I saw a couple defocused stars once, they loss them while trying to adjust.  Any hints on focusing this thing?

 

I'd be happy to hear any comments or help, particularly in locating a target.  With my visual scope, I'm used to the 2 or 3 star alignment process.  But this doesn't translate very well with a camera more or less permanently installed. I know after this I still need practical hands on with the histogram, but might be ready to actually take a picture of something.

 

Thank you for any help!



#2 endlessky

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Posted 05 July 2020 - 12:03 PM

Hi, I'll try to help with what I can.

 

I think for the slewing commands to work as planned, you need to set not only a correct time on CdC (but it should get this time directly from the laptop, so just make sure it is correct there), but also and equally important the correct location (longitude and latitude) of where the telescope is located. This doesn't need to be "exact", just go on Google maps, find your home location and use those coordinates for the home location on CdC (the odd 10-15 meters won't matter much).

 

Another pointer I can give you is this: if the slewing is off, do not make the corrections by disengaging the clutches and manually moving the axes, otherwise the motors (and the software) won't have any idea of what those corrections are and where the telescope is now pointing. Use the arrow keys on the hand-controller (if you connect the laptop or PC through your hand-controller) or the arrow keys on EQMOD (if you connect the laptop or PC directly to the mount, using the hand-controller port) to move the mount and center the object. If you use the function slew and sync, which most plate-solvers have, you shouldn't even need to give any input manually, as the program will move the mount for you until the object is centered (within the provided tolerance) in the frame.

 

As far as guiding, I can't tell you much, because I don't have a guiding setup. Sounds like it could be focusing issues, though. You should try slewing to a bright star and try focusing there, before you slew your scope to the final imaging location (where the stars could be not bright enough to show up - if out of focus - on your guide camera).

 

Hope this helps and clear skies!


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#3 ESzczesniak

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Posted 05 July 2020 - 12:19 PM

Hi, I'll try to help with what I can.

 

I think for the slewing commands to work as planned, you need to set not only a correct time on CdC (but it should get this time directly from the laptop, so just make sure it is correct there), but also and equally important the correct location (longitude and latitude) of where the telescope is located. This doesn't need to be "exact", just go on Google maps, find your home location and use those coordinates for the home location on CdC (the odd 10-15 meters won't matter much).

 

Another pointer I can give you is this: if the slewing is off, do not make the corrections by disengaging the clutches and manually moving the axes, otherwise the motors (and the software) won't have any idea of what those corrections are and where the telescope is now pointing. Use the arrow keys on the hand-controller (if you connect the laptop or PC through your hand-controller) or the arrow keys on EQMOD (if you connect the laptop or PC directly to the mount, using the hand-controller port) to move the mount and center the object. If you use the function slew and sync, which most plate-solvers have, you shouldn't even need to give any input manually, as the program will move the mount for you until the object is centered (within the provided tolerance) in the frame.

 

As far as guiding, I can't tell you much, because I don't have a guiding setup. Sounds like it could be focusing issues, though. You should try slewing to a bright star and try focusing there, before you slew your scope to the final imaging location (where the stars could be not bright enough to show up - if out of focus - on your guide camera).

 

Hope this helps and clear skies!

Thank you!  I did find an pretty bad location error.  I had set the location, but it seems accidentally to E longitude instead of W.  I'm sure that did not help at all!

 

The only reason I disengaged the clutch was to try and get the plate solve location to match reported telescope coordinates.  Through the Tool-->Plate Solve in SharpCap, it does not sync and slew, only solves and reports the coordinates.  So I wanted the mount to be unaware of what I did, otherwise it would have updated to new coordinates that would still had a similar error margin.  Another point I now realize though is that I was looking at the time wrong, thinking in AM/PM format.  The scope reported 10:30 and I was expected it to be 00:40.  I was 13 hours off, not a little over an hour.  And that is pretty close to the 12 hour difference with my location erroneously being on the opposite side of the globe. 

 

And once I get the goto, yes, it seems a bright star will be a good place to start for focusing the guide scope. 



#4 endlessky

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Posted 05 July 2020 - 12:33 PM

Glad I could be of help. Don't worry, we've all been beginners at one point. This stuff is hard and you will feel that you are wasting clear skies to smooth out problems and battling with issues: optical, mechanical, software. Everything is against you, at first. But once you make it work, it becomes second nature and you won't even think about it.

 

One other thing you could do, since all these problems are software and trial/error related, is keep practicing this during the daytime. If you know roughly where Polaris is (for example, from your living room), point your telescope there, start CdC, connect everything and start slewing to a star or object on the map, for example due East, at 20° above the horizon. After the slewing is complete, is the telescope pointing where you expect it to be pointing (East and 20° above horizontal)? Issue a sync command, and go to another object. Did the telescope move as expected? Is it pointing - roughly - where you think the object might be in the sky if it was dark (judging by the map and a compass, for example)?

 

The more of these things you can fix during the day, when the sky conditions do not matter, the less you will have to deal with that one rare occasion that the night sky is ideal for observing / imaging.



#5 SonnyE

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Posted 05 July 2020 - 02:36 PM

Never expect instant success. This is Astrophotography or Astroimaging. (I've decided I'm an imager, and I often take picturds. But hey, we walk before we run.) lol.gif

Due to equipment failures and inadequacies, it took me literally years (~2) to finally get something I thought was half good.

I can't count the number of nights I packed it in and walked away shaking my head, only to return the next night and get a little further, a little better.

Just don't give up, and don't stop. Because you will get there.

 

It baffles me why you would go through your PA, then ruin it by releasing the clutches and moving your RA and Dec to "Zero". Maybe you have a plausible explanation, but what you did completely negates the PA. confused1.gif

I do things a way I learned with my woefully terrible AVX. I take aim at Polaris, I adjust the ELV and the ALT-AZ to center Polaris in my Main telescopes camera. Then do a Polar Drift Alignment with PHD2. After that, I go right into my alignment (Modeling in Losmandy speak).

Then I do 3 Westerly stars, 3 Easterly stars, and back and forth until my target stars are landing as close to centered as possible.

Then when I chose a victim to suck the light out of, it comes up nudge close to my main telescopes cameras cross-hairs.

I'm completely unorthodox, but I do get results. And I go by my results, not by graphs, or other foo-faw. Pictures, even bad ones, never lie.

 

Not having your settings correct is a rookie mistake. Welcome to the human race! I bet you don't do that again, and I always go the long way and check my settings routinely, as my mount starts up. Just assures me that I tried.

I use an app on my phone that gives me GPS coordinates, (Just the compass part) and it is highly accurate. I feel it is better than using a town or city. I enter in the GPS coordinates I get into my location.

(FYI: Phones generally get updated routinely. So their GPS data is usually fairly accurate. Bought GPS devices go out of date on their data. So I like my phone for the task.)

 

I think you have great equipment listed. I think you just need time to get use to it, and to build confidence in using it. Something I found extremely good for me was looking through You Tube videos about specific things I didn't quite grasp.

The best part was being able to pause, back up, pause, try the settings shown, and progress.

If you have any questions about stuff, like PHD 2 even, there are helpful video's by folks in the same boat. Like PHD Basics 1, and PHD Basics 2. He gives the basics to get going, and you can try twiddling the settings to find perfection for your equipment at your location.

 

But just keep chopping, you'll get there. And remember you're only Human.

I've always like Forrest Tanaka's video's as well. 



#6 imtl

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Posted 05 July 2020 - 03:24 PM

Never expect instant success. This is Astrophotography or Astroimaging. (I've decided I'm an imager, and I often take picturds. But hey, we walk before we run.) lol.gif

Due to equipment failures and inadequacies, it took me literally years (~2) to finally get something I thought was half good.

I can't count the number of nights I packed it in and walked away shaking my head, only to return the next night and get a little further, a little better.

Just don't give up, and don't stop. Because you will get there.

 

It baffles me why you would go through your PA, then ruin it by releasing the clutches and moving your RA and Dec to "Zero". Maybe you have a plausible explanation, but what you did completely negates the PA. confused1.gif

 

Releasing the RA and DEC clutches does not ruin PA. If he would have touched the alt-az alignment knobs then that would of course be true. When we released the RA and DEC clutches we ruined the mount goto model of the sky unless the mount has encoders. It has nothing to do with PA.

 

The fact that the OP could not solve and sync but were able to only solve points to something. How is the mount being controlled?

 

And, does the mount have an option to "search" for zero position?


Edited by imtl, 05 July 2020 - 03:27 PM.


#7 Stelios

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Posted 05 July 2020 - 04:15 PM

I am very new to astronomy, as many of you may be guessing after I've already posted a handful of topics.  I started visual astronomy about 3 months ago and tried my first actual night session with a DSO AP last night.  Based on what I was planning to accomplish, I can't say it was a complete failure, but I need help/input. The AP setup I have is:

 

1. WO Zenithstar 81 mm

2. WO 50 mm guidescope

3. ASI 290MM guide camera

4. ASI 294MC-P Imaging Camera

5. EQ6-R Mount

 

And software:

 

1. SharpCap

2. CdC

3. PHD2

4. AstroTortilla

5. Necessary ASCOM/EQMOD drivers

 

I've spend the last month or so reading and setting up all the software and hardware as far as I can.  During the day when there's nothing to see through the camera, all interfaces seem to work well. 

 

Last night I attempted a practical session.  Yes, the 4th of July with a full moon is a poor night, but I wasn't planning to actually image anything.  My goals were:

 

1. Polar Align

2. Goto align the scope

3. Guide on a star

 

Not surprising, I ran in to some troubles and was hoping this is where I could find some help.

 

1. Success! - I used the SharpCap PA tool and by their numbers, had to 2-2.5 arc minutes of accuracy.  I know it'll need to be better, but since I wasn't planning on actually imaging, stopped fiddling a bit early.  The SharpCap PA tool is a plate solver, so I also proved on the main scope that I could focus (rough, then using the SharpCap FHWM tool) and adjust gain/exposure to get a good star field. 

 

2. Failure - This is where my real struggles were and I'm hoping for help.  I set the home position of my scope a while ago, trying to be very careful, based on this link: https://www.myastros...om/homeposition .  After PA, I shut down the scope and software, returned the DEC and RA clutches to zero and locked them.  Then powered the scope and software back up.  I then loaded CdC, connected the scope, and slewed to the target.  In SharpCap on the scope control, I selected solve and sync and it failed.  I then used the plate solve under tools and it did successfully solve a plate providing my RA/DEC.  The point it solved was only about 0.5 degrees off DEC, but about 1:40 off RA.  Not sure why.  That's one place I'm hoping people could help with.  Perhaps I had mismatched Epochs?  Not sure if the error is this big or not.  Anyway, I tried to troubleshoot, I unlocked the RA clutch, rotated the roughly 1:40 and locked it again.  Through the plate solve tool I was now about 0.5 degree on DEC again, and RA was about 00:01:15 off the reported scope position.  So I tried solve and sync again...and failed again. 

 

Now complicating this, I didn't realize my date, time, or location in CdC was clearly off.  It didn't register to me at first.  The target selected was M31 showing about 40 degrees of altitude in CdC.  Seemed a little fishy since I haven't seen it until about 3:30 AM visually and it's a known fall targer, but again it didn't register at the time.  Would this affect the solve and sync thought?  It seems to me that it is just trying to match plate solve coordinates to where the telescope thinks it is pointing.  So even if M31 wasn't at DEC 39.6 and RA 00:45:??, something is and it'll solve those coordinates?  And it did plate solve just fine from tools, just not the "solve and sync".  But perhaps time did enter somewhere here in the equation.

 

3. Failure - I couldn't get any starts to show up here.  I am sure the lens cap was off.  Most of my experimenting was with about a 2 second exposure and gain around 200.  I think the issue was focus.  I had tried focusing on a distant daytime object.  But as I found with main scope, the infinity focus can be a long way off a 300 meter terrestial focus.  This is the guide scope: https://williamoptic...h-1-25-rotolock . The focus is simply by sliding the eyepiece or camera along the visual back, then locking it.  I think I saw a couple defocused stars once, they loss them while trying to adjust.  Any hints on focusing this thing?

 

I'd be happy to hear any comments or help, particularly in locating a target.  With my visual scope, I'm used to the 2 or 3 star alignment process.  But this doesn't translate very well with a camera more or less permanently installed. I know after this I still need practical hands on with the histogram, but might be ready to actually take a picture of something.

 

Thank you for any help!

The moment you unlocked the clutch and made a move, the software was lost (applies to all mounts *without* absolute encoders). 

 

What you need to do in order to get your GoTo working, is to slew to a star, and then CENTER that star using either the handcontrol or its emulation in software (then rinse and repeat for a couple more stars to refine). What you *did* is simply get information as to where your first slew landed you. There was zero benefit to your plate-solve--other than finding how far off you were, a laborious exercise to no real point. The first slew is almost invariably quite a bit off. 

 

A platesolve that *would* have worked, would have been if, in a software such as SGP, you had input a star in the target coordinates. Then SGP would slew to that star, and plate-solve to CENTER on that star. You can probably do that with Astrotortilla but I haven't used that software in 7 years so I forget how it works.

 

Here's how to make your life easier:

 

1) Align your guidescope and the main scope. Right now the Moon is your friend. Slew to it. Center it (using the handcontrol or software--NEVER release clutches) in the main camera (might as well get a decent focus while you're at it). Now without touching the scope, adjust the rings on the guidescope so that it, as well, has the Moon centered. Get the Moon focused in the guidescope. [You will be using Sharpcap for all this focusing. You will have to use very low exposures (milliseconds) as the Moon is bright--don't be afraid to reduce exposure. When you move OFF the Moon, you will need to raise exposure to a couple of seconds or even more for stars, but your cameras and scopes will remain in focus].

 

2) When star-aligning (after polar aligning) slew your scope via CDC. Find the star in the guide camera (see (3) for what to do if it's not in the guide camera's FOV). Center it with the handcontrol or software keypad emulator. The star will now be in the main camera's FOV. Center it in the main camera. Now go to CDC and press Sync! Repeat for a couple more stars (these will likely be in the main camera's focus from the start). That's it. You are now star aligned and can perform GoTo's. Note: No plate-solving involved. 

 

3) If the star is NOT in the guide camera's FOV (raise exposure to 4 or 5 seconds in case it's just too dim), then simply sight along the optical axis with your eye, and use the handcontrol to nudge the scope in the direction of the star. Then look in the guide camera again.

 

4) For *real* plate-solving, you want to START the plate-solver with the coordinates of what you want to Go To (or want to image). Then the solver will take an image, determine where it actually is (it may need to blind solve if you are way off), and know how far off it is from where it should be. It will then automatically slew your scope to where it should be, take another image, and iterate until it's "close enough" (as defined by you) or it has exceeded maximum iterations (again, as defined by you). 

 

Although real plate-solving is a huge game changer, I consider it to be definitely later on in the learning curve after polar aligning, star aligning, focusing, learning how to guide, and learning how to take calibration frames. It's not essential, and it can be highly confusing at first. 

 

Remember that once you got the guide scope focused on the Moon, you can now refine it further by focusing on stars. And after it's focused, you LOCK that position and never, ever, touch it again. 


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#8 ESzczesniak

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Posted 05 July 2020 - 05:29 PM

Unless I'm very mistaken, unlocking the RA clutch will not change polar alignment.  The telescope is rotating along the RA axis, which isn't changing.  I was purposefully trying to make the telescope think it hadn't moved, but correcting it to the plate solve location manually.  Effectively, a manual sync.  The software didn't think it moved, but manually I updated the coordinates.

 

Now that I'm aware of my location error, this may have attributed to all or most of my error. 

 

The way I'm understanding it, plate solve and sync vs 2/3 star alignment are conceptually doing the same thing, but in the opposite order.  In the former, you go to a expected coordinates (relative to home position), solve the plate, and then update them with the real coordinates.  In 2/3 star alignment you go to known coordinates (star), then update your expected coordinates.  Correct me if I'm not understanding this correctly. 



#9 ESzczesniak

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Posted 05 July 2020 - 05:33 PM

A platesolve that *would* have worked, would have been if, in a software such as SGP, you had input a star in the target coordinates. Then SGP would slew to that star, and plate-solve to CENTER on that star. You can probably do that with Astrotortilla but I haven't used that software in 7 years so I forget how it works.

 

Correct me if I'm wrong, but I think this is what I did.  CdC slewed the telescope to the current RA/DEC coordinates relative to "home position".  CdC input the coordinates of the object.  The plate solve is supposed to then determine what these coordinates really are, then sync the telescopes real position.  SharpCap is effectively using AstroTortilla for the plate solving, and the original coordinates are what CdC spits out. 



#10 Stelios

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Posted 05 July 2020 - 06:24 PM

Correct me if I'm wrong, but I think this is what I did.  CdC slewed the telescope to the current RA/DEC coordinates relative to "home position".  CdC input the coordinates of the object.  The plate solve is supposed to then determine what these coordinates really are, then sync the telescopes real position.  SharpCap is effectively using AstroTortilla for the plate solving, and the original coordinates are what CdC spits out. 

When CDC slews, it slews to the actual coordinates of the star, based on an assumption you're in home position and that the date, time and geographic coordinates are accurate. 

 

The plate solve happens in Sharpcap. It finds the actual position it is in now. It's there, so there's nowhere for it to go--it's happily pointing to where it was pointing (a tautology). So how does this help you? It knows where you are in the sky. It knows nothing as to where your mount is oriented. It could've been any position, anywhere. It has a single position--where it is now.

 

To sync your scope, you need to go from position A (park position at time and location) to position B (position of a known star, e.g. Vega), and verify the total *actual* motion needed (initial slew plus adjustments to center star) for this move. If what you were doing could work, you would not need to move from park position at all! You could just platesolve whatever THAT location (park) is. 

 

If you were to input the coordinates of the star you wanted to go to (the actual *absolute* RA/DEC coordinates using J2000 or JNow according to what Astrotortilla supports) in Sharpcap (leaving CDC out of it entirely) then you could slew-and-sync to those coordinates from the park position. This would establish a new position and that (2 positions plus coordinates and date/time) is all that's needed to model the scope's location with respect to the sky. Adding extra stars refines things further and corrects for slight imperfections in alignment and also things like cone error.

 

And although loosening the clutches does not at all affect Polar Alignment, it totally destroys any knowledge the scope has of where it is. The scope (mount, actually) still thinks it is where it was *before* you loosened the clutches. It does not know it moved at all. 



#11 ESzczesniak

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Posted 05 July 2020 - 06:45 PM

When CDC slews, it slews to the actual coordinates of the star, based on an assumption you're in home position and that the date, time and geographic coordinates are accurate. 

 

The plate solve happens in Sharpcap. It finds the actual position it is in now. It's there, so there's nowhere for it to go--it's happily pointing to where it was pointing (a tautology). So how does this help you? It knows where you are in the sky. It knows nothing as to where your mount is oriented. It could've been any position, anywhere. It has a single position--where it is now.

 

To sync your scope, you need to go from position A (park position at time and location) to position B (position of a known star, e.g. Vega), and verify the total *actual* motion needed (initial slew plus adjustments to center star) for this move. If what you were doing could work, you would not need to move from park position at all! You could just platesolve whatever THAT location (park) is. 

 

If you were to input the coordinates of the star you wanted to go to (the actual *absolute* RA/DEC coordinates using J2000 or JNow according to what Astrotortilla supports) in Sharpcap (leaving CDC out of it entirely) then you could slew-and-sync to those coordinates from the park position. This would establish a new position and that (2 positions plus coordinates and date/time) is all that's needed to model the scope's location with respect to the sky. Adding extra stars refines things further and corrects for slight imperfections in alignment and also things like cone error.

 

And although loosening the clutches does not at all affect Polar Alignment, it totally destroys any knowledge the scope has of where it is. The scope (mount, actually) still thinks it is where it was *before* you loosened the clutches. It does not know it moved at all. 

I don't think I'm understanding what I did that is different than what you're saying.  I did start in the home position.  And from there slewed to a new position.  I then try to "sync" this position with coordinates from a plate solve.  I'm not understanding how what you're saying is different from what I did.  The coordinates change in SharpCap as they change in CdC and the ASCOM controller.  I don't know if I understand how entering the coordinates manually vs them being read through the ASCOM drivers is any different. 



#12 17.5Dob

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Posted 05 July 2020 - 08:52 PM


 although loosening the clutches does not at all affect Polar Alignment, it totally destroys any knowledge the scope has of where it is. The scope (mount, actually) still thinks it is where it was *before* you loosened the clutches. It does not know it moved at all. 

THIS +1

I use an Orion EQ-G...and I never bother with plate solving...or even more than a 1 star alignment...

My first GOTO is ALWAYS  nearly centered, and a 1 star alignment is more than enough...

You just need a good PA and a good definition of home before you slew...NEVER try to do anything manually...


Edited by 17.5Dob, 05 July 2020 - 09:00 PM.


#13 TelescopeGreg

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Posted 05 July 2020 - 10:09 PM

What Stelios said.

 

Summarizing, "Syncing" is knowing where the optical train is actually point at (that's what a plate solve does), and telling that to the mount.  The software does this.  Then you do a GoTo again, and using the new information, the mount should move exactly to the right place.  Sometimes it might take two tries, but the mount will eventually get there.  I think you're thinking about it backwards.  No manual intervention is required, nor desired. 

 

I'm using CCDciel, but the operation should be the same.  I tell the software to go to some object in the sky.  It looks up the coordinates, and commands the mount to go there.  Using the scope's camera, it takes a quick image, and does a plate solve.  That's invariably wrong by a little bit (or a lot, it doesn't matter).  The plate solve software then talks to the mount, telling it where it really is, and the mount updates its internal model of where it is in the sky.  Then the software re-does the slew to the target, the mount slews, and another test images is taken and solved.  If it's within whatever you've specified for accuracy, it's done, otherwise the cycle repeats until it is.  All I did was one mouse click; it did the rest.  And I can do this without any alignment other than a good polar alignment, and starting the mount from its index marks (home position).  Magic.




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