Control Your GTO Mounts
with Your
Keypad, Computer or Mobile Smart Devices

Full-size Version

As this chart shows, there are many options available for controlling your mount whether you are out for a night of observing your favorite objects without a PC (your Keypad serving as your handheld computer), conducting a public star party (imagine using an iPad to "WOW" the kids) or remote imaging (APCC will allow you to control your mount in the comfort of your home).


Your Astro-Physics GTO mount has a remarkable servo control system that combines with the precise mechanics of the physical components to give the mount its superb performance. Contrary to popular assumption, the brains of the mount is found in the GTO Control box, not in the kkeypad or computer program. Simply think of your Keypad or computer as an input device.

Computer Control
All functions of the servo drive can be commanded from a laptop or desktop computer. Astro-Physics now has a wholly-owned and fully-supported ASCOM V2 driver for all of our GTO mounts. This is the recommended method for mount control with a personal computer operating under the Windows operating system. Most popular Windows planetarium, imaging, guiding and observatory control software take advantage of ASCOMís universal applicability. Refer to additional information regarding the V2 driver below.

The GTOCP3 control box provides two RS-232 inputs so that you can connect with two separate serial interfaces. This allows Mac users and non-ASCOM programs to have more than a single connection to the mount. For example, you might wish to connect PulseGuide and an ASCOM client at the same time with your Windows computer. On the Mac side, you might wish to connect both Astro-Planner and Equinox for an observing or imaging session. Please note that we cannot fully support Mac programs at this time.

Serial-to-USB connectivity has been simplified by the addition of Keyspan Serial-to-USB devices to our product line, and the Icron Ranger USB Extender. Please review the information regarding connectivity products to determine which one will work best for your set-up.

GTO Keypad Operation

The GTO Keypad (included with all GTO mounts) is a handheld computer with all of the features, functions and databases you need to tour the universe night after night. The vacuum-fluorescent display with a temperature range down to -40 degrees F (and C, they are the same in this instance), allows hardy observers to use the keypad on cold winter nights (please contact Astro-Physics if you wish to use the mount in severe temperatures below -20F). Additional information regarding the features of the keypad are at this link: GTOCP3 Control Box and Keypad for Servo Drive.

As new firmware versions are released in the future, you can upgrade your keypad directly from the download section of our website - free of charge!

The Keypad was included with all GTO mounts and is compatible with all versions of the GTO Control Box: GTOCP1, GTOCP2, GTOCP3

PulseGuide™ Software

PulseGuide is a stand-alone Windows (98, ME, 2000, NT4, XP, Vista and Windows 7) utility that provides complete remote control of the Astro-Physics Mach1GTO, 900GTO, 1200GTO, 3600GTO, 400GTO and 600EGTO mounts. It derives its name from its most distinctive feature, pulse guiding, which can improve unguided tracking. Specifically, it can help correct tracking errors caused by polar misalignment and atmospheric refraction. You can also train PulseGuide to track objects moving relative to the stars, such as asteroids, comets, and the moon. In addition to pulse guiding, PulseGuide also has many useful utility features. With just a few exceptions, it supports the entire serial Astro-Physics command protocol allowing full control of your mount through your PC. More information here ....

PulseGuide was written by Ray Gralak of Sirius-Imaging. Please refer to his web site for further developments and enhancements. All owners of any Astro-Physics GTO mounts can download the software free-of-charge, courtesy of Ray. Many, many thanks to Ray for this powerful program.

PulseGuide is compatible with all versions of the GTO Control Box: GTOCP1, GTOCP2, GTOCP3

Astro-Physics ASCOM V2 Driver

Astro-Physics now offers a company-supported ASCOM V2 driver. This driver provides full mount control for all of the Astro-Physics GTO mounts and acts as a hub allowing multiple client applications to connect through a single serial port without the need for POTH. It has been developed with remote operation in mind and its functions were designed to be highly robust. The driver features a very user-friendly graphical user interface (GUI).

Please see this link for more information and to find links to the ASCOM platform and the Astro-Physics V2 ASCOM driver.

The ASCOM V2 Driver is compatible with all versions of the GTO Control Box: GTOCP1, GTOCP2, GTOCP3

Astro-Physics Command Center (APCC) Software

Ray Gralak, the author of PulseGuide, is currently developing the Astro-Physics Command Center (APCC), which will incorporate all the features of PulseGuide and add many more advanced functions to the control system of your mount. Through the application of virtual serial ports, APCC will act as a hub for a number of other applications that can all communicate with the mount through a single COM port. As of this writing, in late May 2011, APCC is in the second beta testing phase. We anticipate that it will be available later in the summer 2011.

APCC can only be used with the GTOCP3 control box since it takes advantage of advanced features available only in the CP3.

Planetarium, Imaging and Observatory Software from Other Vendors

There are a number of planetarium programs that can be used to control the Astro-Physics GTO Servo System. In addition, some software designed primarily for camera control and/or observatory control and planning also have limited ability to control your mount. Many of these use the ASCOM interface and will take advantage of the new ASCOM V2 driver mentioned above. Any software that can use the AP V2 ASCOM driver will have extensive mount control capabilities because of the driver's "virtual keypad" features. Other programs employ native drivers that the software designers wrote from our publicly available command set. The list that follows is certainly not exhausive, but contains software with which we have at least a little familiarity.

Resources for Mac users

In addition to the Mac software mentioned above, check out this resource: The Mac in Astronomy by David E. Illig. Website:

Mobile Smart Devices

We have entered a new age of smart devices that offer amazing functionality at our fingertips without the need for a computer.

SkyFi Wireless Telescope Controller from Southern Skies

SkyFi is Southern Skies' patent-pending WiFi-to-Serial adapter is designed for wireless telescope control. If you have a computer-controlled GoTo telescope, SkyFi can use the WiFi capabilities built into your Mac, PC, iPhone, iPad, or iPod Touch to point your telescope (via your mount) in the sky.

In 2010, Southern Skies' SkyFi and SkySafari (discussed below) were Macworld Expo 2010 Best of Show winners (both products were marketed by Carina Software at the time of the award). Check this link to see Tim Benedictus demonstrate these products at the Macworld Expo.

SkySafari from Southern Skies

As of this writing, SkySafari 3 is available in three different versions, two of them offering telescope control. All of these versions are available as iTunes Apps and require use of the SkyFi Wireless Telescope Controller, as described above . The GoTo mount control functions provided by this application are quite basic and most suited to visual astronomy. However, the graphical interface if your iPad, iPod Touch or iPhone offers some exciting possibilities to engage kids (young and old) at public star parties, as well as provide an enjoyable, informative evening for amateur astronomers on observing nights. Also, if the weather is cloudy, you can browse through the extensive databases to learn a great deal about the sky and plan your next session.

Please go to the Southern Skies website for the most updated information on SkiSafari and SkiFi.

Write your own computer program

The Astro-Physics GTO protocol for the GTOCP3 Control Box is freely available to those who would like to write their own computer program for controlling the mount. Please contact Astro-Physics for further information. Please note, however, that with our substantial investment in both the Astro-Physics V2 ASCOM driver and in APCC, we cannot also provide free technical support to anyone who wants to try their hand at mount control software. We strongly encourage all customers to use the available software options, if possible.

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This page was last modified: June 15, 2011

Astro-Physics, Inc.
11250 Forest Hills Road, Machesney Park, IL  61115, U.S.A.
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