Previous: Guide fibre bundle focussing
Up: Installation and Setup for Fibre observing
Previous Page: Guide fibre bundle focussing
Next Page: Setting up FOS
The spectrograph setup procedures for long slit observing are described
above. The plane and tilt of the fibre slit
can in principle be different from those of the long slit, the difference
in the plane of the slits causes a difference of the distances from the
fibre and long slits to two collimators. Because spatial resolution is
important, the spectrograph should be set up to provide a collimated beam
onto the grating. The nominal values of the collimator settings
for long slit observing to provide such a situation are 7000 microns for the
Blue arm, and 9000 microns for the red arm. The procedure to ensure that the
spectrograph is correctly set up for fibre observing is as follows:-
- With the slit unit in the long slit position, set the two collimators
to their nominal values.
- Ensure that the spectrograph can be focussed with the collimators
near these values, by making adjustments to the capstans on the
CCD cryostats, as described in Section 8.3.2.
- Ensure that the tilts of the focal planes are correct, again by
adjusting the capstans as described in Section 8.3.2.
- Ensure that the rotation of the CCDs is such as to align the
long axis of the chip with the dispersion direction, again as
described in Section 8.3.1.
- Move the slit carriage to the multislit position with the command
MSLIT, and remove the Acquisition and Comparison mirror.
- Switch on the fibre calibration lamp.
- Using the Hartmann procedures, focus the spectral lines from the
fibres onto the CCDs by moving the collimators.
- Correct for any residual tilt along the fibre slit by making
balanced moved of the CCD capstans, i.e always keeping the
centre of the focal plane in the same case.
The difference between the collimator position for best focus for the
long slit and for the fibres should be the same, and of the same sign,
for both red and blue arms.
Previous: Guide fibre bundle focussing
Up: Installation and Setup for Fibre observing
Previous Page: Guide fibre bundle focussing
Next Page: Setting up FOS