There is a diagonal mirror in the TUB used to direct light
into the science instrument, guide camera, both or neither.
The four positions for the diagonal mirror can be selected
from the sdiagmir_fe program. sdiagmir_fe is started by clicking
on its icon on either the gouda or karnak computers.
|The standard diagonal mirror is shown at right, with a total field of view of approx. 330" x 240", which the guide camera (with a field of view of about 120") can access by moving it on an x-y stage. The hole for light to go to the instrument is about 2 arcminutes in diameter, thus limiting the field for direct imaging using the mirror in position 3. Other diagonal mirrors are available which have larger holes, giving a wider field of view at the Cassegrain focus, but limiting the area in which to locate off-axis guide stars. For example, the Gemini IR camera, uses a different diagonal mirror so that a field of view of 3 arcminutes is possible.||
Standard Cassegrain Diagonal Mirror
Last modified: Thu Mar 4 12:28:37 PST 2010