Having solemnly resolved…

Unboxing the Celestron CG5 ASGT Mount

After an arduous trip from China to America to Indian shores and Calcutta via a short halt in Customs at Mumbai, the Celestron CG5 ASGT Advanced Go-to mount is finally here!

Here’s a small ‘unboxing’ post, for the mount and two accessories

  • The Celestron CG5 ASGT
  • The Polar Finderscope
  • The 17A Celestron Powertank battery pack

The mount, item #91518, came in a fairly large brown cardboard box, with a gross weight of 35 kgs. That is with one counterweight, but when bought in combination with a larger scope, this mount comes with two counterweights.

Shipping box for the CG5 ASGT

As you can see, the box is huge. My Thinkpad L421 is shown for scale. There was a double-box of corrugated cardboard, inside which were 4 more smaller boxes.

Double Packing Boxes

The longest box contained the folded tripod feet, tucked between styrofoam blocks at both ends. This box also contained the accessory tray (a cast-metal spacer-cum-eyepiece-holder triangle) that goes between the feet to hold them apart. The tripod feet are capable of extending quite a bit, and I don’t immediately understand why they extend till so long.

Tripod Feet

I first set up the tripod, with the accessory tray.

Accessory Tray

The metal spacer and weight goes below the accessory tray, not above. Reviews say the CG5 has its limitations, but from first impressions this seems to be a rock solid tripod.

Where do people hang out on the other continent? At the Counterweight Bar!

Another box has a nice heavy counterweight.

A Counterweight

Since my first goal is wide-field astro-photography with only a DSLR, the counterweight might not see immediate use.

The actual mount

The actual mount was in another box, with custom foam inserts. It also came with two little allen keys (hex keys) which I didn’t end up using at all. I needed other tools, though. Even my tiny Orion Mini-EQ came with a more complete set of needed tools. This is something Celestron ought to think through.

Azimuth Adjustment Counterscrews

Since all my potential observing locations in India [(Calcutta, 22°35’N), (Mumbai, 18°55’N), and (Hyderabad, 17°22’N)] are below the CG-5’s lower limit of 30° latitude, the mount won’t work without some modification.

I removed both latitude adjustment screws (the front one is shorter, the rear one is longer). There is a small plate behind the front latitude adjustment screw (see pic). This plate is secured by two screws. I removed these using my own #5 hex key, following online instructions from Celestron.

Removing the bar behind the front latitude adjustment screw

Remove the plate that holds the latitude screw from the front side of the mount. Since it is on the same side as the counterweight, it is really not needed when the scope is in use, as equatorial head’s weight is always resting on the back latitude screw. Taking the plate off allows the latitude of the head to be lowered to your location.

The unneeded parts

So the ‘unneeded’ parts go back into the box.

But note that this modification reduces the mounts stability, in that it might increase the chance of the mount tipping over in odd positions – typically when the counterweight is absent or when the mount is pointing in an extreme direction.

Now works at lower latitudes

This modification extends the minimum latitude of the Celestron CG5 ASGT from 30° to around 7° or 10°, which covers almost all of India except the southern tip. If I ever happen to be in those parts, I will have to adjust (tilt) the tripod legs for polar alignment.

The next modification is also low-latitude specific. The mount needs to be installed 180 degrees rotated from the original position on the tripod, to prevent the counterweight from banging into the foot at low latitudes.

To prevent this, take the equatorial mount head off the tripod, exposing the top of the tripod. You will see the square-shaped azimuth adjustment post. Unthread the post from its current position in line with the single tripod leg and move it to the threaded hole 180 degrees away located between the tripod legs. Reassemble the head to the tripod.

Caution: this rotation of the head on the tripod will shift the scope’s center of gravity, increasing the likelihood of toppling the mount. Tying or weighting of the opposing tripod leg is recommended in this situation.

Since I can’t find an appropriate tool to ‘unthread’ the little square azimuth adjustment post, I leave this for later.

Now to install the polar scope.

The unboxed Polar Scope, with a Blackberry 9900 Bold for scale.

Had some trouble figuring out how to remove the finderscope housing. I had to cover one of the three thumbscrews in soft paper and hit on it with a heavy tool to get the housing to loosen. The entire thing rotates counter-clockwise and comes off.

Unscrewing the finderscope housing part with the 3 screws

The polar scope attached. Not a perfect fit.

I didn’t like that the polar scope doesn’t fit flush with the mount, but it’s no big deal.

View from the Polar Scope

View from the Polar Scope

Finally the mount goes on top of the tripod. This is pretty simple, especially without any counterweights. I think various little things on the mount might be needed to be tightened once the weights pile on.

The CG5 ASTG mount on the tripod

Opening the next box, I found the Nexstar hand controller, a declination cable, two plastic pieces that comprise the hand controller holder, a cast metal dovetail and a car lighter plug cable. Attaching the controller holder and wiring up the controller were simple.

The hand controller and accessories

Power up!

Time to power the mount up! I attached the provided car lighter cable to the Celestron Powertank, and… er, no response? I noticed the power jack on the mount has to be pushed in real firmly, and has a screw connector for more secure attachment.

Pushed it in harder, and the mount powered up. Success!

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