- Object is too faint.
- Atmospheric conditions: thick overcast or poor seeing - for the
latter problem, use a larger entrance aperture.
- Object not on `hot spot' - recenter object.
- Bonnette guide probe not at position (x,y) = (0,0) - have telescope
operator return guide probe to correct position.
- Entrance shutter to interferometer closed - open shutter.
- Dewar dark slides closed - open dark slides.
- Incorrect preamp gain setting - try more sensitive preamp setting.
- Preamp switches on sides of dewars turned off - turn on preamps.
- Dewars are not at nominal operating temperature - check temperatures
and vacuum manifold readings.
- If, after investigating all the possibilities listed above, there
is still no measurable signal, the sensitivity of the detectors should
be
tested using the white light source internal to the interferometer. To
do this,
turn on the white light source and position mirror 2. Next, select the
He I
filter; the IR1 beam splitter should
also be
in place. Set the preamp gain to `1', and display the `S1' signal on the
oscilloscope. Turn the rheostat on the control panel which varies the
power
to the white light source. The strength of the S1 signal should vary. If
not, try the `S2' signal. If no change is apparent contact CFHT
personnel.