USB Guide Port Interface (GPUSB)

Taking images of galaxies, nebula, and other deep-sky objects require precise tracking. To achieve this, astrophotographers use a computer to keep the telescope pointed at their target (a galaxy, for example). It is done by using a software to analyze the images captured by a camera and then send instructions to the telescope’s mount whenever the target drifts, so as to keep the telescope properly pointed. This automatic telescope guidance system is called autoguiding.

Autoguiding requires a means for a computer to send guiding signals to a telescope’s mount. For most mounts, especially the entry-level ones, a separate device can be used to enable the computer ‘talk’ to the mount—an example of which is a USB Guide Port Interface or GPUSB.

GPUSB_ShoestringAstronomy
Note that the port on the left and the toggle switch on the right are simple modifications done to allow the GPUSB to be connected to my DIY Mount Controller, which will be discussed in future posts.

A GPUSB is a device that allows a computer to send guiding signals to a telescope mount. It has a cable that connects to a computer (through the USB port) and another cable to connect it to the mount (through what is called an ST-4 port). With a GPUSB, guiding software such as PHD2 or GuideMaster can now send commands to the mount, to move the telescope in any of the four directions: North (Dec+), South (Dec-), East (RA-), or West (RA+) during autoguiding operation.

Night Sky in Focus
Astronomy and Amateur Radio
© Anthony Urbano (Manila, Philippines)

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