Ad Astra Observatory

http://www.asahi-net.or.jp/~zs3t-tk/aim/aim.htm

Hi all,

My latest project is to see if I can build myself a set of Digital Setting
Circles for my new astronomy mount, which does not have an onboard pointing
computer. In short, I am trying to construct a device which will tell me
the Right Ascension and Declination at which the telescope is pointed.

The mount already has rotational encoders installed on both axes, so it’s

simply a matter of reading some initialization values from these encoders
(by pointing the telescope at two reference stars of known position, for
instance), and using those to create the basis for a “telescope coordinate
space”.

Then, it is a matter of doing a coordinate transform from “telescope
coordinates” (angle of deflection of the axes of the mount) to “equatorial

coordinates” (right ascension and declination).

Much searching on the ‘net revealed this URL:
http://www.asahi-net.or.jp/~zs3t-tk/index.htm, from which I got the
attached PDF. It details the matrix transformations necessary to do the
coordinate transformation needed (as well as some other useful transforms,
such as alt/az to RA/Dec, polar alignment error, and others).

My task, now, is to convert the formulae into code, and to build up the

circuit necessary to drive the sensors, display, clock, and whatever other
subsystems are needed.

As the two people I know who are most interested in both linear algebra and
astronomy, I thought you’d be interested in the paper and website.

Best,
Jimbo

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