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Acquisition and guiding

Select the brightest guide star from the GSS list, and move the guide probe to the correct position
         SYS> autoxy xxx yyy
Issue the FIELD command on the TCS User Interface
         USER> field
and wait for the star to appear during raster scans. If the star is very faint allow several scans to ensure that the autoguider is seeing a real star and not just scan noise (cursor jumping randomly after each scan). The autoguider raster scan is 2 arcmin square with 5 arcsec pixels.
Issue the ACQUIRE command
         USER> acq
The star is scanned in a maltese cross and attempts are made to acquire the star. The probes are moved to centre the star in the scan and a "NEW FIELD" message appears. If attempts to pull in the star for guiding are successful, the profiles of the star will be displayed, and the message "OK TO GUIDE" will appear. Note that one can use
         USER> acquire tel
to move the telescope rather than the probes to centre the guide star.
Give the GUIDE command
         USER> guide
and wait a few seconds for the tracking cursor to appear within the seeing disk below the field raster display, then finally....
press the F18 key or type
         USER> autoguide on

During autoguiding, if the star is lost for any reason (e.g. cloud) as signified by a "CLOUDY" message and the tracking cursor leaves the seeing circle and takes wild random jumps, then immediately press F17 (or AUTOGUIDE OFF), and re-acquire as above.

When going to a different source use

         USER> autoguide off
         USER> agstop
to disable the guide loop and to stop the guider. If you want to resume guiding after issuing the AGSTOP command, you will have to do the FIELD-ACQUIRE-GUIDE sequence again.

If autoguider freezes, then power off-on, then re-acquire.

next up previous contents
Next: Exposing Up: Observing Previous: The Guide Star Server