Frequently Asked Questions:

Q: With the Sidereal Technology system, will I need telescope encoders on my telescope?
Only if you have a clutched system, or a system where the driver rollers may slip. If you have a geared or belt drive system without drive rollers, or if your drive rollers don't slip much, then you don't need telescope encoders.

Q: If I want to use the Argo Navis™ or Sky Commander to control the telescope, then do I need telescope encoders?
No. The SiTech Servo Controller sends the telescope's position to the Argo Navis on the serial port. You really don't need telescope encoders if your drive system doesn't slip.

Q: I have a roller drive system, and it slips enough that I need external encoders. Do I need a “box” such as the MG-III to connect to these encoders?
No, the external telescope encoders connect directly to the SiTech Dual Servo Controller.

Q: I've seen encoder systems where you couldn't move the telescope too fast, or the system would “miss” encoder ticks. Is this true with this system?
No, these are extremely high speed telescope encoder inputs. You can even gear the encoders up, for more resolution.

Q: I only want to track, I don't need a GOTO system. Do I need a computer, an Argo Navis™, or Sky Commander?
No. The Sidereal Technology Servo Controller will track your equatorial or Alt/Az telescope, all by itself, using the DragNTrack™, SlewNTrack™, or Equatorial modes.

Q: What are the DragNTrack™ and SlewNTrack™ modes?
These two modes, along with the Equatorial mode, can be configured using ServoConfig, the supplied SiTech configuration software. Once configured, the SiTech controller will track your telescope without having a computer or other controlling device connected.

- If you have an Alt/Az telescope, with external telescope encoders, you should use the DragNTrack mode, whether you have clutches or not. If you have a clutches you can “drag” your telescope around the sky as if it were a normal DOB, and it will track at the proper altitude and azimuth rates, for extremely accurate tracking.

- If you have an Alt/Az telescope without external telescope encoders, then you should use the SlewNTrack mode.

- If you have an equatorial system, you should use the Equatorial mode.

Q: What is ServoConfig™?
ServoConfig™ is a Windows based configuration program that allows you to configure the Dual Servo Controller. It is very easy to use, offers many features, online help, and has great documentation. There are many features such as finding how many encoder ticks for one revolution of the scope, or to calculate the mechanical backlash of your system.

Q. How many speeds can I select with the handpad?
If using the wireless handpad, there are 3 selectable speeds. If using a wired handpad, there are two selectable speeds. These are configured with ServoConfig to be any speed you like.

Q. How fast can I slew with the SiTech Dual Servo Controller?
A. That depends on your final gear ratio. We have a 16” Alt/Az scope for trade show use. This scope will slew faster than 12 degrees per second (Horizon to Zenith in about 8 seconds, including Ramp Up and Ramp Down!).

Q: I heard that the BBAstrodesigns/Sidereal Technology system is difficult to configure and use. Is this true?
No, not anymore. When first released, the configuration software was primitive, and difficult to use. ScopeII from BBAstrodesigns requires Java Runtime to be installed. It is extremely powerful, and any software with so many features, and with this much accuracy, can be challenging to learn. ScopeII requires a fast computer.

-Now there is free and easy to use SiTech Windows configuration software: ServoConfig.

-There is now a free, accurate, and easy to use ASCOM driver, that connects to any planetarium program. ScopeII is not required.

-You can now control with an Argo Navis or Sky Commander™.

-Technical support is free, email responses are returned promptly, and free phone support is available if required. Dan Gray's cell phone number is in the manual!

Q: What is ASCOM?
: ASCOM is an interface between astronomy software, such as Planetarium programs, and a driver written by a manufacturer of a telescope, or telescope control system. This means Planetarium programs can send standard commands to the ASCOM interface, which dispatches the commands to the telescope driver. This makes it easy for telescope manufacturers (like Sidereal Technology) to have computer control of the telescope from virtually any planetarium software.

Q: Can you tell me more about the SiTech ASCOM driver?
Yes, We have many users already. It is way more than a typical ASCOM driver now. In effect, it is a complete stand alone telescope program, that can be controlled by many other programs, all at the same time. Dan Gray has spent over 2 years perfecting the control of all three telescope types, Alt/Az, Equatorial, and German Equatorial (GEM). Many beta testers wish lists have been incorporated.

The ASCOM driver setup:

Q. Do you need the Argo Navis to be connected for the ASCOM driver to work?
No, all you need is a computer with a serial port, or USB to Serial converter. You need the free ASCOM platform installed.

Q: I notice on the configuration that the ASCOM driver has mounting error compensation. How can I find the mounting errors of my telescope?
A: You use the “Sync” function, from any planetarium software, sync to at least 10 stars, and the telescope mechanical errors will be calculated for you. These mechanical errors can be saved to the configuration. Dramatic improvement in both pointing and tracking are obtained. Dan Gray is getting better than 2 arc minute Average Pointing Accuracy with his 14” telescope.

Q: I want to add a focuser that is ASCOM compliant, how can I do this?
A: You purchase a second controller and use the “Azimuth” channel for a focus motor. If you use the SiTech ASCOM driver, the focuser software is built in. It can be controlled using FocusMax, for perfect, automatic, focusing every time!

Q: I want to add a field de-rotator to my alt/az telescope. How can I do this?
A: You purchase a second controller (unless you've already a SiTech focuser motor). You use the “Altitude” channel for a field de-rotator motor. If you use the SiTech ASCOM driver, the field de-rotation software is built in.

Q: Does the system have PEC (Periodic Error Compensation)?
A: Yes. In fact it will read many of your worm periods, manually synced, or automatically synced (if you have a worm alignment detector). It will automatically remove any drift, then average as many “runs” as you wish, for extremely accurate PEC compensation. Here is a picture of the PEC control window: The lines you see were actual deviations that the SiTech ASCOM driver and Controller collected, then averaged, using a home made right ascension worm gear. The dark blue line is the average, and this is sent back to the controller, for automatic PEC playback.

Q: Any other features of the SiTech ASCOM driver worth mentioning?
Yes, many! There is automatic polar alignment, easy script running, for slewing to objects, or panning large objects, Online help, Audio feedback (plays wave files) Offset tracking rates for following comets, asteroids, and the moon, stand alone operation, with database of all NGC, IC, Messier, and about 200 named stars, for stand alone goto/and syncing, and much much more!

Q. Does the system have a Spiral Search feature?

A. Yes, and no. No, because, it's not a spiral. Yes, because it's a superior search routine! We call our search routine the “Local Search”. We've found that a true spiral will either miss sky, or have too much overlapping sky. Our local search feature is a series of circles, each larger than the other. It remains a true circle regardless of your altitude or declination. You can pause, reverse, speed up, slow down, during the search, and you have two radius choices, all from the handpad. The radii must be set up using the supplied configuration software, and can be set up for any radius distance. The local search works with any controlling device, or in the stand-alone mode.

Q. What about panning and guiding? Are they constant speed, or do the speeds increase while nearing the zenith (celestial pole for equatorials)?
These are configured for “Equal Area Panning and Guiding”. The closer to the zenith (celestial pole for equatorials), the faster the azimuth/RA panning and guiding are. The stars appear to move the same amount, whether centering with altitude/Dec, or azimuth/RA. Once you experience this, you won't want to go back!!!

Q. Can I control the telescope with a PDA?
Cyrille Thieullet has started supporting the SiTech controller in his Palm program, AstroMist. This is really killer software for the Palm operating system. Soon to come is a JavaME program, that can be connected using a Bluetooth to serial adapter. Any PDA with Bluetooth, a Java runtime, and CLDC version 1.1 (think Cell Phone here) will be able to control the telescope using full GoTo's and Tracking!

Q. How do I mount the motors on the telescope?
There are many ways, but Sidereal Technology can supply you with a Dob kit, with gear reducers, with/or without clutches, bearings, etc. We're also excited about the possibility of Tom Osyposki from Equatorial Platforms, providing an installation service.

Q: I don't have a lot of money, but I have a laptop, and I can follow schematics, and am a telescope maker, so I can make my own handpad, and wire my own motors. What's the least I can spend, and have a full GoTo telescope system?
Buy the Controller for $350.00 (without ScopeII/III). Find surplus D.C. Servo Motors with encoders built into the motors (maybe $50 each). Wire your own handpad. Mount the motors on your telescope, using ideas already developed from the ATM community. You will be able to control the telescope with a computer using the free ASCOM driver from SiTech. Total, about $450!!! Inconceivable!!!

Q. I want to take photographs with my telescope. Is this possible with the SiTech system?
The SiTech system is easily configured for photography. We recommend purchasing a wireless handpad, so the auto-guider can be connected to the receiver. This is an industry standard connector, where you can plug an SBIG or other standard auto-guider. The autoguiding works extremely well, because of the “Equal Area Guiding,” Backlash compensation, and instantaneous corrections. The auto-guider inputs are acted upon within milliseconds. Check out the latest astro photography on our website at

Q: Does the system have built in backlash compensation?
A: Yes. This is set up with the ServoConfig software. It is instantaneous, and works wonderfully.

Q: What is available in the Dob kits:
A: You can choose a clutched system, or a direct drive system. The direct drive system is more economical, as you won't need telescope encoders, or the clutches. You also don't need to replace the Teflon bearings with ball bearings, so there is cost savings there as well. We sell a gear reducer with a motor already mounted on it, with a good gear ratio ideal for a belt drive. If you want a clutched system, we sell a gear/reducer clutch mechanism, and we also sell bearings that replace the DOB Teflon pads.

Q. What if Sidereal Technology comes out with new features. How can I upgrade?
. SiTech has 3 software products: (1) The firmware in the telescope controller. You can download the latest firmware from our website, and install it using Servoconfig. (2) ServoConfig software. (3) The SiTech ASCOM driver. These will always be free for downloading and upgrading. ScopeII is provided by BBAstroDesigns, but upgrades are free as well. If you purchase ScopeII, you will have a free upgrade to ScopeIII when it is released.

Q. How much does the system cost?
A: Visit our Pricing Page  

Q. Can I make my own handpad in order to save money?
Yes. All wiring information is documented in the manual at

Q. I'm a telescope manufacturer or a dealer. Can I get a quantity discount?
. Yes, please contact us.

Q: Where do I buy the system?
Visit our Pricing Page