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Shoestring GPUSB Auto-Guider Kit
A low cost, practical, auto-guiding connectivity kit
Shoestring auto-guiding kit
  • Auto-Guiding solution with Shoestring's GPUSB interface
  • GPUSB plugs directly to PC USB Port
  • RJ-12 cable connects to mount
  • Software compatible with:
    • ASCOM platform
    • AstroArt
    • MaxImDL
    • MaxImEssensials
    • MaxDSLR
    • K3CCDTools
    • Guidemaster
    • GuideDog
    • ...and others (see below)
Shoestring Astronomy
Interface Cable
CCD Camera
Shoestring GPUSB Auto-Guiding Kit
The Auto-Guider kit contains:
  • GPUSB Guide Port Interface (PC USB port).
  • Includes USB cable to connect to the computer.
  • Includes RJ-12 cable to connect to telescope mount (normally available separately).
Guide Port conversion kit for non-GOTO mounts. + £9.00
Order No. Price (inc_VAT) Shipping Delivery click to purchase
SSAGKITU £ --- £ ---
User Manual 1.2
Guide Port Cabling 1.0

It is now easy and inexpensive to set up your own autoguiding system. You'll need:
  • PC or laptop computer (e.g. Windows 2000/XP/Vista/7/8).
  • Camera dedicated to auto-guiding (e.g. Opticstar PL-131M COOLAIR, etc).
  • An interface between the computer and the mount (Shoestring GPUSB kit supplied here).
  • Autoguiding software (e.g. AstroArt see below).
With the control software the computer can talk to your telescope mount and direct it's motion. Many telescopes come with a six pin port that looks like a phone jack. This is called an RJ-12 connector.
Typically, a hand controller or CCD autoguider is plugged into this port. Until now, anyone wanting to implement camera auto-guiding that had this type of port would have to buy a relay box that would connect to the parallel port of the computer, and then would need to be wired to the guide port. These relay boxes are fairly large, and are one more thing that requires a power source.

Alternatively the Opticstar AG-131M COOLAIR (monochrome) and the Opticstar AG-131C COOLAIR (colour) provide all-in-one auto-guiding solutions including 1.3 megapixel cameras, Shoestring GPUSB, cables and software.

Shoestring auto-guiding kit
Techical Details
The GPUSB guide port interface adapter plugs directly into a USB port on your computer or a USB hub attached to your computer. Using an RJ-12 cable, the adapter connects to the guide port of your telescope mount. This guide port interface uses optocouplers to electrically isolate the computer from the telescope, eliminating a possible source of electrical interference. This interface adapter requires no external power source since it receives its power via the USB cable. More information can be found in the user manual.

Warning About Cables
The use of improperly wired cables with mounts can result in damage to the electronics in the mount, as well as damage to the interface adapter. The importance of using a properly wired cable cannot be stressed enough. If you choose to make or buy your own from another source, please be sure it is built per the description in the user manual.

ASCOM Compatible
Shoestring Astronomy has developed an ASCOM driver for the GPUSB. Using this driver, any autoguide software package that supports the ASCOM standard will work with the GPUSB.  Most telescope mounts are ASCOM compliant. Therefore even if your auto-guiding software package does not support the GPUSB natively, the chances are that it can still be made to work via the ASCOM software platform. Please follow these steps in order:
  1. Download and install the ASCOM platform from the ASCOM website.
  2. Install the Shoestring Astronomy's GPUSB ASCOM Driver for the GPUSB from the link above.

Missing A Guide Port?
The Meade LX90 series telescopes may need the Meade 909 port accessory that adds an ST4 port to the mount.
LX90 accessory.
The Meade 909 port accessory.

Missing A USB Port?
If your computer does not have a spare USB port but it has a parallel port, then you can use the Shoestring GPINT-PT Auto-Guider Kit that plugs directly to your computer's parallel port. Shoestring GPINT-PT.
Telescope-Mount Support
Any ASCOM compatible mount with an ST-4 compatible autoguider port should work with this adapter. Mounts tested so far include:
  • CG5 (requires Shoestring's Guide Port Conversion Kit)
  • EQ3 (requires Shoestring's Guide Port Conversion Kit)
  • EQ5 (requires Shoestring's Guide Port Conversion Kit)
  • EQ5 PRO SynScan
  • EQ6 PRO SkyScan via the hand controller
  • HEQ5 PRO SkyScan via the hand controller
  • Vixen SPHINX
  • Vixen GPDX via SkySensor 2000 (requires Shoestring's SkySensor 2000 converter)
  • Vixen Altux via SkySensor 2000 (requires Shoestring's SkySensor 2000 converter)
  • Losmandy GM-8 or G-11, without the Gemini box.
  • Losmandy GM-8 or G-11, with new-style Gemini box (circular DIN connects to connect motors).
  • Takahashi EM-10 (requires Shoestring's Guide Port Converter for Takahashi mounts)
  • Meade LX-200.
  • Meade LX-90.
  • Celestron Nexstar i-series.
  • Celestron Celestar 8.
  • Celestron Advanced Series GoTo.
  • Celestron CGE.
  • Orion Atlas EQ-G style.
  • Gemini G-41.
  • Astro-Physics AP900 QMD.
  • JMI NGT.
  • Tom O. Equatorial Platform.
With modification, you can also add an ST-4 compatible autoguide port to your EQ style mount. See the Guide Port Conversion Kit for details.

System Testing With GPUSBCheck
GPUSBCheck is a simple, free software application by ShoeString Astronomy that you can use to verify that your GPUSB, computer, and scope mount are all together working properly. You can download this using the link above. You should use this the first time you set up your system. You can also use it as a debugging tool anytime your system is not functioning properly. If your system works fine with GPUSBCheck, but not with your third-party software, then the problem most likely lies with the third-party software and you should contact them for technical support. If your system does not work with GPUSBCheck, then you should contact Shoestring Astronomy for technical support.

Software Support For Auto-Guiding
The Shoestring GPUSB guiding kit (supplied here) is currently supported by the following software applications.

Software Application Shoestring GPINT-PT Shoestring GPUSB
(supplied here)
GuideDog by barkoSoftware Yes Yes (via ASCOM)
MaxIm Essenstials by Diffraction Limited Yes Yes (via ASCOM)
MaxIm DL by Diffraction Limited Yes Yes (v 4.52)
MaxDSLR by Diffraction Limited Yes Yes (v 4.02)
AstroArt by MSB Software Yes Yes
K3CCDTools by K3 Yes Yes (v 3.00)
Guidemaster by Matthias Garzarolli Yes Yes
AstroVideo by COAA Yes no
MetaGuide by Frank Freestar8n Yes Yes
PHDGuiding by Craig Stark Yes Yes (natively or ASCOM)
Autostar/Envisage at Guidestar LX200 Emulator Yes Yes
Astro IIDC (Macintosh) by ASC no Yes
Equinox (Macintosh) by Equinox no Yes

Sample Images
The following photograph has been taken using the Shoestring , GPUSB/GPINT-PT. Please click on the images below to expand to their full size.
Click to enlarge to 2175 x 2842. Click to enlarge to 1331 x 1019.
M42 & NGC1977. Click on the image to enlarge to 2175x2842 pixels. Image by Dave Moulton captured in the UK, GPUSB (GPINT) auto-guiding kit.
M81 & M82. Click on the image to enlarge to 1331x1019 pixels. Image by Dave Moulton captured in the UK, GPUSB (GPINT) auto-guiding kit.

We are constantly checking the accuracy of the technical data. We are prepared to provide more detailed information on request. Technical data is subject to change without notice.

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