Starlight Xpress Lodestar guider - Manual (Page 4)

Lodestar handbook Issue 1 September 2007
The control of your telescope mount will depend on what inputs are provided. The Lodestar output
connector supplies 4 pull-down lines and a common return line to simulate an ‘ST4’ style autoguider
output. The lines are isolated from the Lodestar electronics by opto-isolator chips and so there is no
risk of damage when connecting the outputs to mounts with unprotected electronics. A standard ‘RJ12’
style output lead is supplied with the Lodestar and this may be connected to any ST4 compatible
autoguider input socket on the mount. It is also possible to guide by using serial data from the computer
to an RS232 input on the mount, but this will be covered later and is less effective than the direct
hardware connection.
The preferred guiding mode is 2x2 binned, as this gives both fast downloads and high sensitivity
without any ‘interlacing’ issues. The ‘Fast’ 2x1 mode is also useful if you are working with a short
focal length guide ‘scope, as it offers somewhat finer RA guiding resolution in the X axis if this is
oriented East-West.
Guiding with the Starlight Xpress software
With the Lodestar connected to the PC and mount, open ‘Lodestar.exe’ and find the ‘Set program
defaults’ menu under the ‘File’ heading. If this is the first run of the software, you will get a warning
about the ‘ini file not found’, but ignore this and click on OK. You should now see a screen similar to
the one shown below:
The settings shown above are generally satisfactory as a starting point, although some will probably
need refinement for best results. In the example shown, the ‘autoguider socket’ on the Lodestar is
providing the control signals to the mount, but you might alternatively use the ‘LX200’ mode via the
serial port of the computer, if this is preferred. The Guiding Parameters are set to 6 pixels per second,
which corresponds to the typical drift rate of a 1000mm focal length guide telescope when the mount is
guiding at 0.5x sidereal speed. Longer focal lengths and/or higher guiding rates will require a larger