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Ursa Minor Autoguider Interface with USB and ST-4 Connections

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0.20 kg
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D2 A9


This USB Autoguider is compatible with all mounts having standard ST4 autoguider port. Here is a list of some popular examples:

The above are just examples. It is not meant to be a full list of compatible mounts.

The USB Autoguider is also compatible with our Ursa Minor Pro Planetarium and Telescope Controller Software 

How does it work?

For long exposure astrophotography it is essential to use guiding. Without guiding you cannot achieve good quality photos with exposure times longer than few seconds because polar adjustment errors and mechanical errors will cause drift in images.

To avoid trailing of the image we should use a separate guidescope on the same telescope mount, and let the computer watch a guide star in the field of guiding camera. The computer should keep the guiding star centered by sending correction impulses to the mount when the guiding star moves out of its original position.


The Ursa Minor Autogider makes a connection between the computer and the telescope mount.

What else would you need?

In addition to the Autoguider Interface itself you will need these accessories too:


  • Telescope mount that can hold two telescopes or one main and one piggybacked or a bigger finderscope, converted to a guiding scope.
  • Guiding scope
  • Autoguide software
  • Guiding camera (purpose made guiding camera (e.g. Loadstar or Mammut) or a highly sensitive webcamera (e.g. Philips SPC900NC))
  • Infrared blocking filter
  • Eyepiece adapter for the camera


Some astronomical cameras have IR block filter and eyepiece mount adapter already installed.

How to use it?


Before using the autoguider, you need to install the driver for USB communication. The autoguider based on the FTDI chip. The detailed description of installation of the FTDI driver can be read from FTDI's homepage. If you do not like to read all that documentation, here is the basic steps of installation:

There are two modes of driver installation: Automatic and manual.

Automatic installation of the driver

You can obtain the driver by downloading this zip file: FTDI_automatic_driver.zip, or you can download it from the homepage of the manufacturer: http://www.ftdichip.com/Drivers/CDM/CDM%202.04.06.exe

This program will automatically install the driver. When the installation finished, zou can connect the autoguider to a free USB port.

Manual installation of the driver

You can obtain the driver from the CD disc or you can download it from the Internet. The driver can be downloaded from the homepage of the manufacturer.

  1. To start installing the driver, connect the autoguider into a free USB port. The computer will recognize it, and starts searching a driver for it.
  2. the "New hardware wizard" window will appear, asking the place of the driver. Please chhose the "Install from specific location (Advanced)" option. A new window will appear asking search options. Please check the "Include this path for searching" option and press "Browse".
  3. A new dialog box will appear, and you should navigate to the folder of the driver. Press "Ok" or "Open" and the driver will be copied and installed.
  4. Now you should restart the computer.
  5. After restarting, the computer will recognize the autoguider and the driver.

Checking the COM port number

After the autoguider connected, the computer will assign a com port number (COM1, COM2...) to it. You should need to know this com port number, because it is needed for use with autoguider programs. The port number can be seen from the Control panel. The method is similar as using USB-serial converter. You can read how to check the com port number on the support page.

Using with GuideMaster

GuideMaster supports this autoguider directly, therefore yo don't have to use ASCOM drivers.

The autoguider uses Meade LX200 commands, so you should choose LX200 as telescope type.

  1. Start the GuideMaster program
  2. Choose General/Setup from main menu. The settings window will appear.
  3. Choose first tab page. This page contains settings regarding to communication with telescope and autoguider.
     Guidemaster screenshot
  4. Choose "LX200" from the options. Choose proper COM port from the drop-down list of ports.
  5. The "Use moveguide commands" should be unchecked.
  6. Please click Save button.
  7. In the main menu choose "Connect". if you don't receive an error message, the communication is established. Four direction buttons will appear in the lower left corner of the window, as shown in this image:
     Guidemaster screenshot
  8. You can check the operation of the autoguider by clicking these direction buttons. As you push one, the program will send correction command, and the red LED blinks on the Autoguider.

Using with PHD Guiding

When you would like to use PHD Guiding program, please download and install the "Generic LX-200 (5.0.1)" ASCOM driver.

You can order the optional software from here:
Ursa Minor Pro Planetarium and Telescope Controlling Software


If the Autoguider doesn't connect.

Please connect the Autoguider ONLY with the PC for testing.
Download the autoguider_test.zip from here:
(use Guidemaster only if you managed to connect with the Autoguider test)
Find out the COM port in your PCs control panel as described here:


Scroll down to Getting the COM port number

(Do not connect the mount to the Autoguider.)
Unpack and run the test program, connect with the COM port number that you found out from your Device Manager and see whether the LED in front of the Autoguider lights up or not.
If it doesn't light up, please contact us!

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