How do I program my flash upgradeable Nexstar* hand control? What about Motor control?

To start, you need the programs that do the updating. Go to Celestron’s downloads page to search for and download and install the latest hand control firmware updates (HCupdate) and motor control firmware updates (MCupdate) programs on your PC (MACs and Linux operating systems are not supported at this time). See the NexStar Resource Site firmware page for information on the various versions.

Step Two: Update the hand control firmware
To update your hand control to the latest firmware version, first connect the hand control to the telescope mount and connect your hand control to your computer, using Celestron’s RS232 cable (#93920). The cable has a phone-style jack at one end (for connecting to the hand control) and a serial connection (DB9) at the other (for connecting to your PC). If your computer does not have a serial port, you can use an accessory serial to USB connection cable (#18775). Similar adapters are also available through most computer supply retailers.

Note: If you have an AUX port accessory (commonly used with the Advanced GT mount), do not use it to connect for updading firmware. It is better to directly connect the hand control to the mount and the RS232 cable into the hand control. If you are using a laptop or other computer with power-down or power-saving options, disable the options so they don't interrupt the flashing and cause problems including failure to update and corrupting/damaging the hand control or motor boards.

Keep the power to the telescope off. Hold down the Info and Undo buttons simultaneously. Turn on the power to the mount while still holding the buttons. Upon power up, release the buttons once you see the Initializing message. You will then see a Transmit Data message. Your hand control is now ready to be programmed using the HCupdate program you installed earlier.

First select your COM port and press Next. You will need to select the correct firmware for your telescope model. NXS versions are for NexStar SE models, CPC models, and all older NexStar models using the new flash-upgradeable hand control. SLT is for NexStar SLT models, and GEM is for the Advanced GT, CGEM, CGE, and CGE Pro mounts. When you click and highlight a specific firmware version, the mount model will be displayed in the field below along with update information.


If firmware for your mount model or the latest version is not displayed here, you will need to click on Download via the Web.

After highlighting your selection, click Next to download the update. Select Start to flash-upgrade your hand control. Press Exit when done.

After you are finished updating your hand control, you need to check that the reprogramming has worked. Turn the power off then on again. Go to Menu > Utilities > Version. The top line should say HC N.NN, where N.NN is the number of the version you chose as the update.

Step Three: Update the motor control firmware
At this point your hand control with a firmware version of 4.13 or later can now update your motor control firmware. This is a different procedure than the hand control update and doesn’t have to be done if there is no updated version for the motor firmware for your mount. You do not need to put your hand control into Transmit Data mode. Just launch the MCupdate program installed earlier and your hand control will automatically display Locked. Next, select the correct motor control version (to find your motor control version you must select “Download via the Web”) and begin the update. The NexStar i and NexStar iSE models use the NexStar GPS firmware, the rest are as shown. If you select an incorrect model, you will receive an error message. The motor control update utility will not update your telescope with another model’s firmware.


When the update is done, check that the update has worked by turning the power off then on and go to Menu > Utilities > Version. Both your new HC and MC versions will be shown.