Hello All,
This has been a busy month for our engineering, machining and assembly crew.
With everyone pitching in, the first of the production mounts are coming off the
assembly and are being hit with a battery of tests. Part of testing has been
done on the bench with new test equipment and software. And of course Howard and
myself have been busy doing night time testing of the prototype and first
production mounts. I just want to cover a few things that you might have
questions about.
First of all, we have been very aware that these mounts may be used in remote
applications, so we have designed many new safeguards (both mechanical and
software wise) to make sure the mounts can not get lost and stay lost. For the
ultimate setup, we have built-in absolute encoders that allow the software in
APCC, or any external software that can read the encoder angles, to determine at
all times where the mount is pointing. Using this information, our servo can be
set to have limits on the east and west side of the mount so that the scope
cannot be tracked or slewed into the pier. The user can also set a home position
to his favorite orientation of scope and counterweight shaft. Home position is
not tied to any particular RA or time data, so no matter how you got the mount
lost (you synced on Vega when the scope was pointed at Deneb?). The home
position is accurate to the arc second on the gear angle.
The encoders have a primary function to eliminate all tracking errors of both
axes, mostly of course to eliminate the periodic error of the worm gear well
below 1/2 arc second. Howard and I did a test last week of unguided imaging with
the 175EDF refractor, 1400mm focal length and 5.4 micron pixel QSI 683 camera.
Howard first did a simple pointing run of 28 points with APCC (all done
automatically while we were inside warming up with a cup of tea). With this
simple model, we imaged for 10 minutes with no guiding whatsoever, and produced
perfectly round stars down to the arc second. Later on we did a PEMPro run of
the drift in the 2 axes, with and without pointing model engaged and recorded
the following: without the pointing model, the overall star drift due to scope
flex, atmospheric refraction, and other effects was approximately 5 arc seconds
(mostly in RA) in a 35 minute time period. With the APCC pointing model turned
on, we recorded a 5 times improvement, tracking the s
tar down to less than 1 arc sec. In fact the drift was now lower than the
atmospheric turbulance. We expect even better performance with a more extensive
pointing model, which may very well eliminate the need for any kind of guiding
in a well aligned observatory setup.
That may be all well and good, you say, but what about those of us who don't
want to spring for the added expense of the encoders. What can you do for our
situation? Well, remember, that the basic accuracy of the worm gear will be
guaranteed to be 5 arc sec or less, and with the apllication of PEMPro, you can
compensate for that down to 1 arc sec or less using the PEM function that has
always been in our mount. On top of that, we will also have optional homing and
limit switches that can be attached inside the RA and DEC axes and set to your
specific needs. Thus, you can set the tracking/slewing limits to any place from
the meridian to the western horizon, depending on your scope setup and the
amount of clearance that you have. Now you don't have to worry that the scope
will continue to track all night and next day if you forget to turn off power,
and wrap all your camera and accessory cords, or run the scope into your
observatory roof. The homing position is also settable, s
tarting off in the Park2 position, but can be moved around to any other spot in
the sky. And of course you can also use APCC to build a pointing model to do
unguided imaging just like above, but within the accuracy of the worm gear and
your PE compensation. The home function uses a mechanical switch to recover the
mount from a lost situation to within 2 - 3 arc minutes. You can then do a plate
solve to get dead nuts on.
The idea of the 1600 was to design a mount that can meet the basic needs of just
about any application, and then can be built upon as the need arises with
hardware and software options. All these options are customer installable, no
need to tear down the mount or send it in. Believe me, even without the
encoders, in its basic mode this is a highly precise mount, second to none. It
can hold a lot of weight, and can shrug off external disturbances like wind load
on long tubes. We have a number of pier and tripod options that cover just about
any application from portable to semi-permanent observatory setups (permanent
piers you will need to engineer on your own).
I am as excited about this product as I have ever been on anything we have ever
made here, and I'm looking forward to seeing some of you in Tuscon and at AIC in
California in the next few weeks.
Rolando
