CFHT operating manual - Homepage Usask

ESPaDOnS: temperature and pressure monitoring http://webast.ast.obs-mip.fr/magnetisme/espadons_new/sensors.html
ESPaDOnS
temperature and pressure monitoring
Temperature monitoring
The temperature of the whole instrument is monitored continuously during the observations and displayed in the status server.
Up to six temperature sensors are installed within the instrument, two within the Cassegrain unit (one in the calibration box and
one in the polarimeter, with an accuracy of about 0.1deg), and four within the spectrograph inner enclosure (one at the bottom
of the transfer collimator, one at the top of the transfer collimator, one on the spectrograph camera and a last one close to the
ccd dewar, the three first being accurate at a level of about 0.01deg and the last one at a level of about 0.2deg).
The observer can also visualise this information
on a specific window (see example on the left)
indicating the temperature from each sensor (first
four lines for the spectrograph sensors and last
two lines for the Cassegrain unit sensors) as well
as the average value and the rms deviation over
the last 50 measurements (all information being
updated every second whenever the window is
active).
With this, the observer can follow in particular
temperature drifts within the spectrograph,
evaluate the consequences on the spectrograph
stability and work out the impact on the data being collected (see thermal response and spectral stability of ESPaDOnS).
Pressure and hygrometry monitoring
The relative atmospheric pressure and hygrometric level within the inner spectrograph enclosure are also monitored during the
observations, and displayed in the status server and in the sensors window (see above image, line 6 and 5). In particular, the
pressure (measured at an accuracy of about 0.01mbar) is the second most important factor on the spectrograph stability and
can thus be used in conjunction with the temperature to evaluate the impact on the data being collected.
© Jean-François Donati, last update May 18 2004
1 of 1 08/07/04 11:32 PM