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Instrument focus

See section 9.3 for how to focus TAURUS in Fabry-Perot mode with the CCD.

The IPCS is a more complex detector to operate than the CCD, and can easily be damaged by overillumination. Its operation is not described in detail here, since it is described in the the IPCS users manual; please read this before using the IPCS.

The focus procedure for TAURUS with IPCS differs in two ways from the focus procedure for TAURUS with CCD. Firstly, it is necessary to open the IPCS shutter explicitly using the IPO command, before an EXPOSE command is issued. After an exposure is completed, the shutter is closed using the IPC command.

Secondly, and most importantly, remember that The IPCS can be severely damaged by over-illumination. Therefore, when observing a calibration lamp whose intensity is not known, the following procedure should be followed.

  1. Switch IPCS to overscan mode by typing OVERSCAN.
  2. Select the maximum possible neutral density filtering for the calibration lamp, using either the COMPFILTA nd or the COMPFILTB nd command. The allowed values of nd for the two commands are summarised in Table 2.
  3. Open the shutter using the IPO command, viewing the IPCS realtime display, and keeping your finger on the IPCS panic button. Hit the panic button if the illumination level is too high.
  4. Gradually reduce the level of neutral density until the illumination level is acceptable.

Thu Apr 7 00:29:52 BST 1994