AZ-GTi Alignment Instructions
https://www.cloudynights.com/topic/658474-skywatcher-synscanaz-gti-alignment-instructions/ Posted 20 April 2019 - 01:15 AM
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 cool.gif
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!
