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Automatic prediction of guide-star positions by Infodisp

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Function:

The Infodisp program can be set to predict the positions of available guide stars each time the telescope slews; the positions are written to the Talker thus:

The positions are given in autoguider-pixel coordinates.

Usage:

Turn the prediction feature on or off using the command

	cmd INFODISP PREDICT {on|off}

Lock the autoguider onto the predicted star with the command

	guide on pixel x y

Notes and caveats:

Due to normal pointing errors, the guide star will be displaced from its predicted position. Normally, it should fall within the autoguider's guide window, but if it does not, turn guiding off again, expand the window and try again:

	guide off
	agwin gui size 100 100
	guide on pixel x y

The autoguider will pull the star in to the predicted position over the first few guide cycles. To avoid bluring the science images, you need to wait for it to centre in the guide box before exposing. This normally takes less than 10 seconds.

The guide star positions are predicted using the HST guide-star catalogue.