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A modern single-channel photometer



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Next: A modern two-channel Up: Sample instrument files Previous: A simple photometer

A modern single-channel photometer

Next, consider a more modern photometer that uses pulse-counting. It has a ``neutral'' filter in addition to standard uvby filters. The ``neutral'' filter is in series with the passband filters, and is used to determine the dead-time correction. The positions of these two filter mechanisms are recorded as two adjacent digits in the data, so we can treat them as a single filter code; the second digit is 1 when the ``neutral'' filter is in the beam.

There is also a shutter whose position is encoded separately in the data stream: 0 means open, 1 means shut. This can be treated as a second logical filter mechanism.

The photomultiplier in this modern instrument is in a thermoelectrically cooled chamber, regulated to run at C (273 K). Table gif shows what we get.

Again, there is only one detector, so we need not include the NDETUSED column.

  
Table: Instrument table file for a two-channel photometer



Pascal Ballester
Tue Mar 28 16:52:29 MET DST 1995