Hi all,

After a couple of days of being “closed for renovation”, the ad Astra
Observatory at Newark, CA is back in business with the new Losmandy G-11 mount.

I had to modify the pier in order to get the mount to achieve polar

alignment; It’s not the prettiest installation, but it works. Only 3 trips
to the hardware store! By the way, did you know that hardware stores are
open before 8am?! crazy, man. crazy.

The new mount is a real “grunt”er compared to the old mount (that is, when
you lift it, you say “grunt”). The head is all aluminum, anodized black,
and looks and feels just so much more *solid* than the CG-5. To my eye,

it’s noticeably larger as well, which is nice, because I’m betting on it to
carry pretty much any telescope I throw at it. I’ve seen G-11s with 14”
scopes (in the 60-75# range) mounted. The G11 is a nice beefy object with a
very precision feel to it. Fit and finish is top-flight. I had to call the
manufacturer for some tech support, and actually got Scott Losmandy himself
on the line! Good old made in the USA stuff (in L.A., in fact; the guy also
builds rigs to hold lights and mikes and things for the movie industry, for

what it’s worth).

There’s no GOTO on the new mount; it was a $1000 option that I couldn’t
afford up front. It’ll cost extra to retrofit with GOTO later, but I may
forgo GOTO in favor of Digital Setting Circles, which tell you where the
mount is pointed, but doesn’t actually move the mount to the position of an
object (call it a “push to” mount instead). The mount has encoders for

DSCs, which are the gears that determine how much the mount has rotated,
but I’d have to buy or build the decoder that can take this information and
turn it into celestial coordinates. For now, I’m back to basics; just me,
the stars, and “I think it’s around *here* somewhere…”. Which is
strangely gratifying, as these things go.

The mount has a “polar alignment scope”, which is the first time I’ve had

one of those. Basically, it’s a reticle that sits in the polar axis of the
mount (which is normally the “hole” through which you sight Polaris in
order to get a rough alignment), that shows the relative positions of the
Big Dipper and Cassiopeia and Polaris; you rotate the reticle until the Big
Dipper is in the correct orientation, then move the scope so that Polaris
is in the correct spot, and bingo! a more or less “accurate” polar

alignment. So I did this, and then decided to test the polar alignment of
the telescope. I use a method that makes good use of my Nikon camera to get
an accurate alignment (details are on my website), and so I decided to run
a check. The longer you run the test, the more accurate the results, but
I’ve found that even a 2 minute test is enough to show pretty granular
amounts of error. So off I went, checking both axes for precision. I had to
check my results several times, because under the 2 minute exposures I ran,
I could detect *no* misalignment! What?! I mean, how accurate can a polar

scope *be*?!

As a final test, I decided to run some unguided exposures; 30 seconds, 2
minutes, and then 5 minutes. This is all with Veronica and the whole
imaging rig onboard ( I haven’t weighed the rig, but I’m betting it’s up
near 30# ). So, no guide stars, just pointed at M13 (something that I knew
I could find without GOTO), got it centered up and focused, and fired off a
few shots. In short, I was floored. The 5 minute image showed some *minor*

trailing. It would have been a “keeper” if I’d been shooting a set of them;
the trailing was noticeable, but there was still enough data there to help
the whole stack. In the 2 minute image, I could detect *no* trailing
whatsoever. *None*. Perfectly round stars. This is after simply mounting,
levelling, and using the polar alignment scope to align on Polaris. In
contrast, with the same telescope/imaging rig, *with a guide star*, I’d

lose about 70% of the images of 2 minutes or longer that I’d shot off of
the CG-5. This is, simply, an entirely different *class* of mount.

I’ll have to check this to confirm, but I’ll bet that if I had done a 5
minute polar alignment test, I’d find that my polar alignment needed some
small amount of tweaking. And that once I did that tweaking, I could
probably get some 5 minute unguided images as well. What I’m saying is that

I think that the trailing I saw in the 5 minute image was the fault of the
polar alignment (ie “my fault”) rather than periodic error (ie “the mount’s
fault”). In my test, I’d only asked it how accurate the polar alignment was
over a 2-minute span…

I am amazed, astonished, stunned, proud… I can not say enough nice things

about my experiences with the Losmandy G-11 so far.

sic itur ad astra, indeed.

Clear skies,
Jimbo

Leave a Reply

Your email address will not be published. Required fields are marked *