206 replies to this topic

[davidparks]

The following information is not official nor authoritarian, it is simply my conclusions from thoughtful testing and careful observation.  All described behaviors are based upon insight and conclusion, not upon actual knowledge of the Synscan code.  In other words, my best guess 

 

Synscan Pro for iOS, ver 1.16.1 seems to have an incomplete Reset Alignment bug whereby the current sky model is not removed from memory.  I have reported this bug to Skywatcher.  Hopefully they will investigate and resolve.

 

Synscan Pro for Windows PC, ver 1.16.0 is correctly removing the sky model from memory when you Reset Alignment.

 

Power on Mount
Axis will be reset to the default position.

 

Synscan Connect
AZ Mode:  The Axis default position will be (0, 0)
EQ Mode:  The Axis default position will be (-90, 90)
Az/Alt will be set to the Axis plus offset of the current sky model.  The offset will be (0, 0) if no sky model exists resulting in an Az/Alt of (0,0) for AZ Mode, or (0, Your Latitude) for EQ Mode.

For Synscan Pro for iOS ver 1.16.1
Synscan will remember the previous sky model and offsets, unless you do the following, in order:
    1. Reset Alignment
    2. Remove Synscan from device memory
If a sky model is present, stars will be listed in Align with Sync

Reset Alignment will sync Az/Alt to Axis in AZ Mode, and Az/Alt to Axis plus Your Latitude in EQ Mode.

Reset Alignment ALONE, DOES NOT remove the sky model, you must also close Synscan, remove it from device memory, and re-launch. (No need to power off/on the mount, or disconnect wireless)(This is an APP ONLY operation to remove the sky model from memory).  Close and re-open is not enough, you must remove the app from background memory.

 

Best Practice:
Always remove the Synscan APP from device memory after Reset Alignment, and then re-open and re-Connect the APP to the mount.

 

Synscan Pro for Windows PC ver 1.16.0 will still retain a sky model if exited and re-launched, as it should. It also correctly removes the sky model when you Reset Alignment.

 

Alignments
Any type of Alignment will add to an existing sky model, or create one if one does not already exist.
Confirming center of any object will add error correction offsets to the current sky model.  These offsets will correct for slight in-accuracies in geographical location/time and mount leveling.  They won’t compensate for any variations in the gravitational constant in your backyard.    The point here is, that the sky model/error offsets can get wonky if your adding new data to an old existing sky model.

 

1-Star Alignment
The mount will slew to the selected star coordinates from current Synscan Az/Alt.  The accuracy is entirely dependent upon the current Synscan Az/Alt being real-world-correct and the accuracy of the mounts level.
Confirming center will sync the Az/Alt to the star coordinates, add the star to Align with Sync, and create the sky model.  The accuracy of the sky model will be based on just the offsets created by the centering action of one star.

 

 

Brightest Star Alignment
Manually center the 1st star. The mount will NOT MOVE to the 1st star, you are expected to slew or move the mount to the 1st star yourself.  This requires you to be able to look up and identify the 1st star yourself.
Confirming center will sync the Az/Alt to the 1st star coordinates.
The mount will then slew to the 2nd star coordinates from the current Az/Alt.  Accuracy will be dependent upon the mounts level and how accurate you centered the 1st star.
Confirming center will sync Az/Alt to the 2nd star coordinates, add the stars to Align with Sync, and create the sky model.  The accuracy of the sky model will be based on the offsets created by the centering action of the two stars, and the error calculated between the 2 stars (linear).  The offsets compensate for level inaccuracies, and will be applied to subsequent Gotos.

 

North-Level Alignment (AZ Mode Only)
This alignment is similar to a Brightest Star Alignment, except you don’t need to be able to identify stars, you just need to know which way is North.
Set the scope/mount pointing north and level.  Bubble level and smart phone compass, and even best eyeball guess is accurate enough in most cases.
Confirming north and level will sync Az/Alt to 0, 0.
The mount will then slew to the 1st star coordinates from the current Az/Alt.  Accuracy will be dependent upon the accuracy of the north and level placement.
Confirming center will sync Az/Alt to the 1st star coordinates.
The mount will then slew to the 2nd star coordinates from the current Az/Alt.  Accuracy will be dependent upon the mounts level and how accurate you centered the 1st star.
Confirming center will sync Az/Alt to the 2nd star coordinates, add the stars to Align with Sync, and create the sky model.  The accuracy of the sky model will be based on the offsets created by the centering action of the two stars, and the error calculated between the 2 stars (linear).  The offsets compensate for level inaccuracies, and will be applied to subsequent Gotos.

 

2-Star Alignment (EQ Mode Only)
The mount will slew to the 1st star coordinates from the current Synscan Az/Alt.  The accuracy is entirely dependent upon the current Synscan Az/Alt being real-world-correct and the accuracy of the mounts level.
Confirming center will sync Az/Alt to the 1st star coordinates.
The mount will then slew to the 2nd star coordinates from the current Az/Alt.  Accuracy will be dependent upon the mounts level and how accurate you centered the 1st star
Confirming center will sync Az/Alt to the 2nd star coordinates, add the stars to Align with Sync, and create the sky model.  The accuracy of the sky model will be based on the offsets created by the centering action of the two stars, and the error calculated between the 2 stars (linear).  The offsets compensate for level inaccuracies, and will be applied to subsequent Gotos.

 

3-Star Alignment
This is the most accurate alignment because error offsets can be triangulated instead of calculated linearly.
The mount will slew to the 1st star coordinates from the current Synscan Az/Alt.  The accuracy is entirely dependent upon the current Synscan Az/Alt being real-world-correct and the accuracy of the mounts level.
Confirming center will sync Az/Alt to the 1st star coordinates.
The mount will then slew to the 2nd star coordinates from the current Az/Alt.  Accuracy will be dependent upon the mounts level and how accurate you centered the 1st star
Confirming center will sync Az/Alt to the 2nd star coordinates.
The mount will then slew to the 3rd star coordinates from the current Az/Alt.  Accuracy will be dependent upon the mounts level and how accurate you centered the 2nd star.
Confirming center will sync Az/Alt to the 3rd star coordinates, add the stars to Align with Sync, and create the sky model.  The accuracy of the sky model will be based on the offsets created by the centering action of the three stars, and the error calculated between the 3 stars (triangular).  The offsets compensate for level inaccuracies and will be applied to subsequent Gotos.

 

Polar Alignment (EQ Mode Only)
Polar alignment in Synscan requires that you first perform a Bright, 2, or 3 star alignment.  I recommend 3 star for greatest accuracy.
The mount will slew to the chosen star for Polar Alignment.
Confirming center will sync Az/Alt and use the offsets plus current sky model to calculate latitude and altitude base adjustments.  Synscan will move the mount accordingly and ask you to center the star using the base latitude adjustment.  Center the star as close as you can using just the one base adjustment.  Synscan will move again and ask you to center the star using the base altitude adjustment.  Center the star as close as you can using just the one base adjustment.
Since you have “pulled the rug out from under” the current sky model by adjusting the base, you will need to Reset Alignment, and perform a new Star Alignment.

 

Synscan Pro for iOS ver 1.16.1 will require that you remove Synscan from memory after Reset Alignment, re-launch Synscan, re-connect in EQ Mode, and perform the Star Alignment of your choice. 

 

The accuracy of the Polar Alignment will generally be good enough for visual, un-guided short exposure imaging, and long exposure guiding.  You can perform another iteration of PA/SA to achieve greater accuracy.

 

Tracking
In EQ Mode, tracking is easily accomplished by setting the RA(Azimuth) gear rate of rotation to sidereal.  This rate is constant.  Accuracy is primarily dependent upon the precision of gear and motor manufacturing.
In AZ Mode, the mount will use the current date/time/location and the object coordinates to calculate the proper gear rate of rotation for both axis.  These rates are variable depending on the position in the sky of the object.  Eastern objects move up faster than they move right, Southern objects move right faster than they move up or down, Western objects move down faster than they move right.  Northern objects don’t go to market, stay home, or go wee wee wee.  If you’re in the Southern Hemisphere than Northern objects do, in fact, go wee wee wee.

 

 

Point-and-Track (AZ Mode Only) 
Tracking does not require an alignment or a sky model.  Select the object from the appropriate list and choose Point-and-Track.
(For EQ Mode, just point the scope at the object and select the appropriate tracking rate from the tracking menu in the upper right corner of Synscan)

 

 

Point-and-Go
Synscan will use your mobile device’s accelerometer to slew the mount to the general area of the sky your device is pointing at.  You can then further refine the position by selecting an object from a nearby object list.  Point your device and press Point-and-Go from the Utility Menu.  You do not need to continue pointing while the mount slews.

 

Although I hope you find this information clear, concise, and useful, I hope even more that we all experience more Clear Skies!

[maxsid]

Wow.. Great summary - thanks!

[trurl]

   

[Tim C]

Hi David - what do you have to do to "Remove Synscan from device memory?"  I wasn't clear what that meant.

 

Tim

[elwaine]

Thank you, David!!!  

[Astrodave]

Hi David - what do you have to do to "Remove Synscan from device memory?"  I wasn't clear what that meant.

 

Tim

It means bring up your list of running apps on your phone and force close synscan. I got in the habit of doing that anyway to synscan and sky safari after resetting alignment and disconnecting the app from the mount. Mostly because I didn’t trust the app to fully reset itself after an alignment. Looks like I was right...

 

Good info David. Boggles the mind that skywatcher is unable to do these things and keeps putting out bugs in their app...

[davidparks]

Hi David - what do you have to do to "Remove Synscan from device memory?"  I wasn't clear what that meant.

 

Tim

 

The need to remove the app from device memory is for Synscan Pro ver 1.16.1 for iOS.   So I’m talking Apple iPhone, of which I have the iPhone X, which has no home button.  Swipe up from the bottom edge to show all the apps running in the background, then drag the app you want to remove from memory upwards off the screen.  If I remember correctly for iPhone models with a start button, you would double tap the start button to show the list of apps running in memory, and then swipe them upwards off the screen.

 

I did not test the regular Synscan for the Reset Alignment bug, only Synscan Pro, and only the latest version 1.16.1 on iOS.  I do not have an Android device to test that version.

 

I haven’t used regular Synscan (not Pro) in quite awhile, but I believe there is only 2 alignment methods available:  Bright Star and North-Level for AZ Mode.  It also does not have Align with Sync which will clearly show you if there are star alignments being held in memory, aka the sky model.  If you are using regular Synscan on iOS, AZ Mode, and you are seeing wonky behavior, you might try the “Remove Synscan from device memory” operation to see if it helps.

[coastaltom]

Thank you so much for creating this great set of instructions David!

[oldguy47]

Great writeup David.  Badly needed.  Skywatcher should hire you to be their Beta tester before releasing their buggy software on the rest of us.

Not bashing Skywatcher however.  I have their wifi dongle and it works great with all my Orion mounts.  My Star Adventurer is great too.

[mkothe]

For me it was not sufficient to reset the alignment and kill the app. I needed to restart the mount in order to get zero axis and alt/az coordinates.

[Tim C]

ah, ok, removing from device memory means killing the app.  I was guessing that was the case, thanks for confirming.

[mxcoppell]

Thanks David.

 

Could you share if it's possible to do star alignment with Plate Solving only? (of course after getting polar alignment done first, using Pole Master in my case).

If it's possible, what's the proper steps of achieving this?

Edited by mxcoppell, 20 April 2019 - 04:56 PM.

[vandactor]

Hi David,

What do you do for daytime alignments, i.e. for solar observing? North-Level alignment and just click ok on the star part?

 

Thanks,

Van

[Astrodave]

I set my tube level and north like I am doing a north level alignment and do a one star alignment on the sun. It tracks very well for me that way. Just remember to set the solar observing option to enabled in the advanced settings or you won’t see the option to align on the sun. You could also manually move the mount to the sun and then use the point and track option on the sun although someone said using the arrow keys to reposition the sun stops the mount from tracking but you would just have to reclick the point and track option again after using the arrow keys to resume. I have not tried this feature so I can’t comment. 

[davidparks]

Thanks David.

 

Could you share if it's possible to do star alignment with Plate Solving only? (of course after getting polar alignment done first, using Pole Master in my case).

If it's possible, what's the proper steps of achieving this?

Alignment with Plate Solving:  I can think of two scenarios:   The first one is my regular routine.  Since we’re talking plate solving, there is a PC and plate solving software involved.  I use  Sharpcap backed by All Sky Plate Solver.  I’ve also used Astro Tortilla, and ANSVR, they all work fine.

 

I use Synscan Pro for Windows PC since I’m running Windows anyway, but you can direct ASCOM on your PC to connect to Synscan on your iPhone. (Same as connecting Skysafari running on a 2nd device to Synscan on your iPhone)

 

Scenario 1:  Using platesolving to center stars during a Synscan alignment.  This is my normal routine.  After polar alignment using Sharpcap, i just start a 3-Star alignment in Synscan Pro PC.  I use Sharpcap to platesolve the centering of the star before hitting the Confirm Center button... repeat for each of the 3 stars.

 

Scenario 2:  Not doing any alignment, just Plate Solve and sync the mount.  This needs to be tested!  I believe there is potential for this to work.  First off, your mounts coordinates have to be “close” to the plate solve, I know you can’t “plate solve from half way across the sky”.  I’m not sure how close, 6 degrees works, 10 degrees is too far.  Setting your scope up in North-Level, or EQ Home, becomes easy enough to be within 5 degrees just by eyeball.  So, that first slew to a target (usually during alignment) is pretty close without any alignment at all.  I also know that a Sync command thru PC ASCOM will register the star in Synscan Align with Sync, and that’s where the magic happens   (Unfortunately an Align command in Skysafari does not register the same way).  But it seems you could just pick a star and Goto in Synscan, plate solve and sync, and voila! You’ve started building a sky model in Synscan.  I will definitely be testing this out!

[davidparks]

Hi David,

What do you do for daytime alignments, i.e. for solar observing? North-Level alignment and just click ok on the star part?

 

Thanks,

Van

No alignment at all    

First you’ll need to go into Advanced, and Advanced Settings, and turn on Observe Sun.  This will allow you to pick the Sun in the Star > Solar System list of objects.

Set your scope either in the Az North Level position, or EQ Home. 

You can then do a 1-Star alignment using the Sun, or:

    Pick the Sun from the object list and Goto, or just use the arrow keys to slew to, or unclutch and swing the scope by hand to target and center the Sun.

If you used Goto, then it will automatically turn Solar Tracking on.

If you used the arrows or just swung the scope to target, then you can either select Solar from the Tracking menu in upper right corner, or pick the Sun from the object list and select Point-and-Track.

 

If you are just going to observe the Sun, simply unclutch, manually swing, re-tighten clutch and use Point-and-Track.

If you are using the Sun for alignment, so that you can then Goto and try to find a daytime planet, use the 1-Star Alignment method, or just pick the Sun from the list and use Goto.  Confirming Center should give you enough accuracy to then Goto and find Venus/Jupiter, etc.

[mxcoppell]

Alignment with Plate Solving:  I can think of two scenarios:   The first one is my regular routine.  Since we’re talking plate solving, there is a PC and plate solving software involved.  I use  Sharpcap backed by All Sky Plate Solver.  I’ve also used Astro Tortilla, and ANSVR, they all work fine.

 

I use Synscan Pro for Windows PC since I’m running Windows anyway, but you can direct ASCOM on your PC to connect to Synscan on your iPhone. (Same as connecting Skysafari running on a 2nd device to Synscan on your iPhone)

 

Scenario 1:  Using platesolving to center stars during a Synscan alignment.  This is my normal routine.  After polar alignment using Sharpcap, i just start a 3-Star alignment in Synscan Pro PC.  I use Sharpcap to platesolve the centering of the star before hitting the Confirm Center button... repeat for each of the 3 stars.

 

Scenario 2:  Not doing any alignment, just Plate Solve and sync the mount.  This needs to be tested!  I believe there is potential for this to work.  First off, your mounts coordinates have to be “close” to the plate solve, I know you can’t “plate solve from half way across the sky”.  I’m not sure how close, 6 degrees works, 10 degrees is too far.  Setting your scope up in North-Level, or EQ Home, becomes easy enough to be within 5 degrees just by eyeball.  So, that first slew to a target (usually during alignment) is pretty close without any alignment at all.  I also know that a Sync command thru PC ASCOM will register the star in Synscan Align with Sync, and that’s where the magic happens   (Unfortunately an Align command in Skysafari does not register the same way).  But it seems you could just pick a star and Goto in Synscan, plate solve and sync, and voila! You’ve started building a sky model in Synscan.  I will definitely be testing this out!

David, 

 

First thanks to all the detailed information. It's my fault - I didn't describe the scenario clearly and smoked the gun.

 

I was inspired by your article about using ASIAir and AZ-GTi for light-weight setup. Before the SW wedge arrives, I started to imaging how the "Solve & Sync" could be done with the ASIAir. Of course, I prefer NOT to do any traditional 1-star/2-star/3-star alignment. Just want to point to an area of the sky and solve & sync. There are some report on ZWO ASIAir facebook page talking about good & not so good experience with the ASIAir. 

 

To my understanding is that I should be able to take a test shot (after focusing of course), then plate solve it and sync to the mount. No traditional star alignment required. Not sure if anybody tried this. 

 

Thanks again!

-Min

[cheesified]

I need some help, I've got the ASIAIR and AZGti working perfectly now.

However I've seem to hit a barrier trying to sync the mount with Skysafari 6 Plus. Need some advise on that, and IP settings.

 

I've been trying to connect SkySaf to the AIR, and I'm using both the iPhone (SkySaf) and Andriod (ASIAIR & Synscan App). Have I got something wrong around here? I'm thinking to repurchase the SkySaf for Andriod but before I make another needless double purchase I hope it's just some wrong settings done. Pretty much confused lol

[tkottary]

I have had no issues with direct plate solving with Ekos for scenario two. Most of the times  I was 6-10 degree out of view and 2 -3 rounds of plate solving got me centered enough (<10') .

[atan]

Thank you so much for the detailed explanation. I’ve been having real issues with my gotos and I’ll try out your instructions next time I’m out. I just want to clarify about the polar alignment routine instructions using the SynScan app. 

 

1. First perform a 2 or 3 star alignment

2. Then polar align with 1 star by adjusting the eq base controls

3. Select Reset Alignment in the synscan app

4. Adjust mount again (loosen clutches) and return the mount to home position

5. Perform a 2 or 3 star alignment again

 

Best,

Alan

[davidparks]

1. First perform a 2 or 3 star alignment

2. Then polar align with 1 star by adjusting the eq base controls

3. Select Reset Alignment in the synscan app

4. Adjust mount again (loosen clutches) and return the mount to home position

5. Perform a 2 or 3 star alignment again

 

Basically your list is correct, however, I’d like to add a few critical details that I hope contribute to your success.

As a precursor, create a User Object > Terrestrial Objects and specify Axis 1 = -90 / Axis 2 = 90. Name it EQ Home. You can Goto this position any time you need to return the scope to EQ Home, and more importantly, any time you need to get your mount to agree with the real world.  If your scope doesn’t actually match after this Goto, then you can loosen clutches and move your mount/scope into EQ Home.  This ensures your mount’s Axis actually matches the real world scope position.  Once it does, don’t loosen your clutches for anything (unless you have turned Auxiliary Encoders on)

 

1. First perform a 2 or 3 star alignment
Before your first alignment:
   1a.  With the GTi power off, loosen clutches and set your scope in the EQ Home position
   1b.  Turning on the power, the GTi  Axis will be reset to (-90, 90), and now matches the actual position
   1c.  Open Synscan, connect in EQ Mode, and check under Utility > Information to confirm that your Axis reads (-90, 90), and the Az/Alt reads (-90, 90).  If it doesn’t, there is likely a previous alignment still in memory.  Reset Alignment and check Utility > Information again.  (Current version 1.16.1 on iOS will require you to close and remove Synscan from memory)
  1d.  Proceed with a 2 or 3 star alignment

 

2. Then polar align with 1 star by adjusting the EQ base controls

   You got it, just follow the Synscan prompts, pretty straight forward

 

3. Select Reset Alignment in the synscan app

4. Adjust mount again (loosen clutches) and return the mount to home position

   Switch these two steps, and don’t loosen clutches

    3. Select and Goto your EQ Home User Objects > Terrestrial Objects. (This keeps your scope and Axis in sync)

    4. Reset Alignment (and close and remove Synscan from memory if you are using iOS 1.16.1)

 

5. Perform a 2 or 3 star alignment again

 

 

Note:  Steps 1a and 1b above is the same as a GoTo your EQ Home User Object, and then loosening clutches to move your scope into the matching EQ Home position.

 

 

Hope this helps! 

 

EDIT:  Oops, the saved EQ Home User Object should be Axis 1 = -90, Axis 2 = 90

AZ Mode North Level is Axis 1 = 0, Axis 2 = 0

Edited by davidparks, 22 April 2019 - 07:37 AM.

[davidparks]

Getting your AZ-GTi right with the world:
Key to successful alignments and GoTo’s are having the following 3 elements in sync:
  1. Digital Axis - This is your mount, where the GTi thinks it is pointing

  2. Physical Axis - This is your scope, where it is pointing in the real world
  3. Synscan Az/Alt - This is the sky model that Synscan uses to translate celestial coordinates into digital Axis positions.

 

You can view your Digital Axis and Az/Alt in Synscan using the Utility > Information screen.

You can confirm a sky model is present if there are stars listed under Alignment > Align with Sync

 

Getting 1, 2, and 3 on the same page:

  1.  Power on your mount, this should set your Axis to (AZ Mode 0, 0)(EQ Mode -90, 90), or

  1.  Create and Goto a User Object > Terrestrial Object for AZ Mode with Axis1 = 0, Axis2 = 0  (AZ Mode North Level)

  1.  Create and Goto a User Object > Terrestrial Object for EQ Mode with Axis1 = -90, Axis2 = 90  (EQ Mode Home)

  2.  Loosen clutches, move your scope into Home position

     Home position for AZ Mode is scope pointing at the due north horizon

     Home position for EQ Mode is shown in my user account avatar picture, pointing at the celestial pole

  3.  Select Reset Alignment in Synscan from the Alignment screen.

     In AZ Mode, Az/Alt will read (0, 0)

     In EQ Mode, Az/Alt will read (-90, 90)

     If Reset Alignment isn’t available, then there is no current sky model and Az/Alt is already in Sync

 

You will also need to close Synscan and remove it from device memory if you are using Synscan Pro for iOS version 1.16.1.  Hopefully this reported bug will be fixed in the next version.  This bug doesn’t effect Synscan for Windows PC.  I don’t know for Android.

 

After any alignment routine, you will notice that Az/Alt no longer matches Axis.  This is the result (and function) of Confirming Center when centering alignment stars.  The discrepancy between Az/Alt and Axis compensates for physical placement errors (north, level, polar, etc.)

 

If you are experiencing wonky Goto behavior, make sure you have your 1, 2, 3’s in order 

Edited by davidparks, 22 April 2019 - 07:39 AM.

[atan]

Once again, great suggestion especially about creating a home as a custom target. If weather turns, hopefully it will be this week. I'm hoping to avoid sending it back for repairs. I like the weight and portability of the mount so far.

[jhbanister]

The following information is not official nor authoritarian, it is simply my conclusions from thoughtful testing and careful observation.  All described behaviors are based upon insight and conclusion, not upon actual knowledge of the Synscan code.  In other words, my best guess 

 

Synscan Pro for iOS, ver 1.16.1 seems to have an incomplete Reset Alignment bug whereby the current sky model is not removed from memory.  I have reported this bug to Skywatcher.  Hopefully they will investigate and resolve.

Last night I kept getting SynScan crashes when hitting the “Back” button from an object.  I received an error message and had to force close the frozen app to get back up running.  Fortunately the alignment endured, and everything worked normally.  Anyone else seen this?  

[Tim C]

Yes, I had this happen once last night. Killing the app and reconnecting did the trick and I didn’t lose alignment.