Handbook for the SXVR-H18
Issue 1 March 2010
21
2) Press the ‘Start’ button and a series of 1 second exposure guider images will
begin to appear in the picture frame. If the images look too dim, use the
‘Stretch Image’ slider to increase its contrast and brightness until the noise
begins to be visible.
3) If you haven’t focused the guider lens or ‘scope, move the mount until a bright
star is visible on the guider image and then adjust the focus until it is as sharp
as possible.
4) At this point, you may want to test the guiding control by pressing the manual
‘Move Telescope’ buttons at the bottom left corner of the control panel. You
can watch the position of any stars in the guider image and confirm that they
move in response to the buttons. The movement should be slow if the correct
guiding rate is selected on your mount (typically 2x sidereal). Adjust this, if
necessary.
5) Move the mount until the required object for imaging is properly framed in the
main CCD image (leave the guider menu and use the main camera control
panel, as necessary).
6) Re-open the guider control panel, start imaging and try to locate a clearly
visible guide star. If necessary, make adjustments to the guide telescope or off-
axis guider until one is found.
7) Press ‘Stop’ and then press ‘Select Guide Star’. Use the mouse to left click on
the selected star and a green cross will highlight it and the co-ordinates will
appear in the text boxes above the image window.
8) The various guiding rate defaults, listed on the right-hand side of the control
panel, are unlikely to be perfect for your particular telescope and mount. You
have the option of manually selecting values, or asking the software to attempt
to determine what they should be. This is done by pressing the ‘Train’ button
and waiting for the software to complete a sequence of automatic moves and
calculations. The training will also determine the angle at which the guide
camera is oriented with respect to the RA and Dec axes. If you do not wish to
train the system at this time, the default values of 6 pixels per second will
serve as a starting point.
9) Now press ‘Go to main camera’ and the guider control panel will be replaced
by the camera control panel. Set the required exposure time for the image (say
5 minutes) and press the ‘Autoguide next image’ button. The autoguider
window will reappear and, after a few seconds, you should see error values
appearing in the text windows at the top. The guide star will be fairly close to
the green cross, although not necessarily accurately centred, and you should
see the power/ guide LED on the rear of the camera brighten and change
colour with each correction.
10) If the star begins to drift away from the cross, despite the corrections being
made, the chances are that the N/S and/or E/W directions are set wrongly.
Judge which axis is incorrectly set by observing the direction of the drift and
then stop the exposure by pressing ‘Esc’. Open the guider control panel and
check the appropriate swap box(es). After this operation, you will probably
need to find the guide star again by taking a guider image and reselecting the
star, as before. Now return to the main camera menu and try the ‘Autoguide
next image’ button again.
11) Once guiding is taking place without problems, the main exposure can be
allowed to finish and, if all is well, you should see an image with tiny circular
stars.
