Celestron's CG5 Advanced Series GT mount: GOTO arrives in Boca
20 Oct 2004. As usual, about a month after my birthday, I have to watch the mailbox fairly carefully. This is the time of year my self-given birthday gifts tend to arrive. Two years ago, for example, my C8 arrived. This year, after several years of fighting a losing battle against light pollution and lack of starhopping ability, I broke down and went for the gusto. Or, to be more accurate, the goto. Someone on Astromart was selling the new Celestron CG5 mount, with the computerized drives and database, for a price I could actually afford. So I went for it.

First ImpressionsCG-5 Clone

The first thing I noticed upon unpacking the carton was how beefy the new 2 inch round tripod legs are compared to the legs sold with earlier CG5s and their lookalikes. The difference is phenomenal. Of course there are heavier legs out there, like on Meade's Giant Field Tripod, or Losmandy's G-11, but these legs are a huge step up in stability. I'm continually impressed by the dampdown time. Even when freight trains are rumbling by (I'm about a block and a half from the CSX tracks in downtown Boca Raton, and we get heavy trains running through frequently) the images in the eyepiece are still acceptable.

One thing that raised a red caution flag was the note that the seller had included: he had had the mount serviced by Celestron, and I was to use his name if I had to contact them. Uh-oh. Not a pleasant surprise...

Upon closer inspection I discovered that the seller had also neglected to include an important article: the power cord! The goto version of the CG5 uses a 2-amp power supply, instead of the more common 1.5-amp draw. Radio Shack doesn't have the cord; the only thing to do was to call a Celestron dealer. Nowhere in Florida had them in stock, so I called Hands On Optics, who promptly shipped me a cord, just in time to test out for Friday night observing. Unfortunately, the person who packed the box didn't realize that he had put in the wrong cord! So now I had the useless 1.5-amp cord!

The only thing I could do with the mount without the power cable was to set the declination axis to match my latitude, 26 degrees North. The mount is only supposed to be accurate down to about 30 degrees North, another fact that surprised me. There's a little bar on the north side of the mount, held on by two allen screws, that blocks travel to lower angles. I removed that, and now the mount reaches the proper angle. No guarantees it'll work, but at least it might...

A week later, the proper cord arrived, and I was able to take the mount out under the stars for the first time. The first thing I noticed was that the mount slewed great in RA, but in Declination the motors whirred but the mount didn't move. Uh-oh. Now I had even greater worries about the undisclosed servicing by Celestron, and the glib advice to use his name if the mount didn't work...

I unscrewed the motor covers and immediately discovered, however, that the problem had a simple solution. The gears had been unmeshed, presumably to avoid damage in shipping. So I broke out the allen wrenches and mated them up, plugged the new cord into my handy-dandy 20-amphour power supply, complete with flashlight, air compressor, and jumper cables, and the mount began to slew properly. Noisily, but properly. I still have to experiment with the balance to get just the right play, but performance has been acceptable, so I'm in no hurry to resume fiddling...

First "Light"

Eureka! Alignment successful on the first try! Each subsquent try has been similarly successful, so I'm quite pleased. And then the acid test: centering objects in the FOV. Every test object I used - M57, M15, M2, M31- came into the low power FOV, and most of them even at 200x. Of course, that's using a 10mm Radian, so the FOV is still fairly large, but my expectations, perhaps unduly low due to skepticism induced by the sketchy-seeming seller, were exceeded!

When I finally got all the parts together and put the C8 on the head, balanced the setup, and took it out under the stars, I ran it through the setup procedures. I entered my observing location, including latitude, longitude, and time, and then chose the "Auto Align" procedure. This involves slewing to three stars. Now, in my backyard, with trees and house blocking strategic portions, it was a bit challenging to find suitable stars to align on -- most of the first choice stars were obstructed. Eventually, though, I was able to get it to find three stars that were visible, center each one first in the finder, then in the eyepiece, and do its little computational dance.

And I've been quite impressed with the mount. I've only had it out a few times, due to weather and personal schedule, but I look forward to many nights of fun!

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