Own a Celestron GEM? Don't Leave Home Without This!

There are any number of minor unanticipated events that can ruin a night of imaging at a remote site.

1. The weather can go bad. A sheet of clouds can roll in seemingly out of nowhere and obscure the sky. The wind can make your scope bounce. A heavy dew or frost can overwhelm your dew prevention gear.
2. You can forget to bring a critical component. Over the years I've managed to forget counterweights, the counterweight shaft, cables, the dew shield for an SCT, and probably more things than I can remember that I forgot.
3. Something can break in a way that simple tools and duct tape can't fix.

It was fault number 3 for me last night. Rather than going through power-up initialization my CGEM's hand control would stop with the display frozen on "Transmitting data..." Cycling the power was ineffective. Switching from AC to DC battery power didn't help. The evening was over before it started. This wasn't so bad at a site only an hour or so from home, but imagine it happening after driving eight hours to the Nebraska Star Party.

What I didn't know at that point was if it was the mount or the hand control that was the problem. Possibly both. Having Celestron fix the mount would probably run well over the $700 I paid in 2010. That's a sizeable portion of the cost of a new Losmandy G-11, a mount that would be a better than good replacement. On the drive home I had a bit over an hour in which to consider all the mounts that might replace my CGEM, and none of them were what I would call inexpensive. Certainly a new mount is not in my budget.

A new hand control would be more acceptable at about $100. Or I could take a substantial risk and go cheap by picking up a used control on ebay for less than $40.

With some trepidation I went online and found that "Transmitting data..." message meant the hand control had lost its firmware and was waiting for a refresh. A simple reinstall of the firmware might fix the issue.

The hand control comes with a cable that to connects its base to a computer through a serial port. As you're probably aware, serial ports are essentially extinct; very few computers still provide them. The workaround is a serial to USB cable called the TRENDnet TU-S9:

TRENDnet TU-S9 (USB 1.1 version)

I have the older model shown above that I used a few years ago to update the control and the CGEM motor firmware. It works fine with Windows Vista and 7. A newer model is white, sells for about $10 on Amazon, and is said to be compatible with Windows XP through 10 and OS X 10.4-10.11. All you need to do to restore the hand control firmware is follow the instructions found in this excellent YouTube video. It takes all of five minutes, and in that amount of time I had my mount back in working condition. My budget was safe!

If I'd had it with me last night, I could have fixed my mount and taken advantage of a beautiful evening.

The moral of this story: If you have a Celestron mount and you're traveling to a dark sky site, avoid a wasted trip. Be sure to bring the cables you need to reinstall the firmware, and if you've got a laptop put the installer on it and a copy of the appropriate firmware version(s) for your mount(s). You can bet I'll be bringing this to Nebraska this year.