Cartes du Ciel is free software released under the terms of the
GNU General Public License
From the menu: Telescope
This interface can be used with an encoder box using Tangent protocols like the Ouranos , AAM or NGC-MAX. It uses a floating two stars alignment method based on an article by Toshimi Taki in February 1989 S&T.
Please refer to the manufacturer information to connect the telescope to the computer and to power. Then use Setup → General → Telescope to select the encoder interface and open the control panel. The following window is displayed:
The first time you use this feature, you need to provide some configuration information.
Click the “Connect button”, the light must change to green and the encoder count is displayed at the top of the screen.
Perform the following alignment procedure:
The position of the telescope is now displayed using equatorial and azimuthal coordinates.
You can now close the interface window by clicking the “Hide” button.
Refer to the main menu Telescope to learn how to display the telescope position on the chart.
Remember you can refine the local precision by using “Sync current object” on a nearby star at any time. You are not limited in the number of initialization stars you choose.
The couple of stars used for the part of the sky the telescope is actually pointed at are marked by a '*'.
The Clear button deletes all the stars in the initialization list and returns the interface to the uninitialized mode.
A right mouse click on the list allows the deletion of one star from the list.
If your interface returns status information, this is indicated just below the coordinates.
Sometimes the position shown on the chart is not the one you observe in the telescope. There are many causes of possible error - here is a short list:
Select the encoder type you use. If your model is not listed consult your documentation to find a compatible model, if you find none select the generic Tangent model.
Set the encoder count for a full rotation for both axes.
The read interval is the amount of time that elapses between two position queries to the interface box. Use a smaller value for a smoother cursor movement if your box accepts that and if your computer as enough power. Use a larger value to use less computer resource or if your interface box has a limited output rate.
Check the mount type (equatorial or Alt-Az) you use and if you prefer to do the first initialization vertically or horizontally.
The mount fabrication error angle Z1, Z2, Z3 in degrees are the ones defined in Taki article:
Measuring Z1 and Z2 can be a difficult task, but Z3 can be of great value in initializing the mount.
For example, if your Dobson mount as a security stop 5 degrees above the horizon to avoid flipping the primary mirror. You can set Z3=5 and check the initialization at 0 degrees. To initialize the mount simply point the telescope tube horizontally to the security stop and click the “Init 0°” button, that's all.
You can do the same if the stop is 15 degrees after the zenith but in this case use the “Init 90°” button.
You don't need to set the observatory coordinates as this is automatically done from the location defined in Skychart.
If there is a problem with the interface you can trace the protocol to a file by checking “Record protocol to a trace file”.
The last check box lets you choose if you want this window always visible at the top of the other.
Select the serial port where the telescope is connected (COM1,… on Windows; /dev/ttyS0 or /dev/ttyUSB0 on Linux; /dev/tty.serial1 or /dev/tty.usbserial-xx on Mac).
Set other options (speed, data, parity and stop) according to the manufacturer's information.
Change the timeout values only if you encounter communication problems and after identifying the problem with the trace file. Do not set the timeout to a value greater than the refresh rate in the preceding screen.
Click the Save Setting button to keep your configuration for the next run.
Also save the default options in Skychart menu to keep your interface choice.