The buttons have fixed diameter and must not collide with each other. The hypodermics have a fixed length and must not be pulled out of their pivots. The hypodermics have a fixed diameter and must not collide with each other or with a button. Each pivot has a position fixed at the time of manufacture, and its neighbors constrain the motions of the fibers across the focal plane. The button at the input end of each fiber has a default ``parked'' position at which it is left when not in use.
The pivots are arranged in ``banks'' of 10 along arcs of a circle (nearly) centered on the telescope axis. There are 10 banks of pivots plus one large coherent guide fiber bundle. There is a detent in the MOS plate at the park locations. A button must not be moved to any location farther from the center than the parking ring, and it must not be within its own diameter of the park location of any button.
The output ends of the MOS fibers are also housed in hypodermics which are aligned in parallel to form a ``slit'' of light as input to the spectrograph. Due to the length of the spectrograph slit and the minimum possible separation of these hypodermics there are currently more pivots than there are installed fibers. Each of the fibers has been individually identified and named so that its condition can be tracked.
Individual fibers can become broken during observing runs. Between observing runs when the MOS is serviced the fibers can be rearranged at both the input and output ends.
mos.par. These include all of the button and fiber diameters, and the length of hypodermic which must remain behind the pivot as leeway.
In the absence of an astronomical position the code is currently using the catalog position from the Astronomical Almanac. This position is now known to be based on erroneous inputs; it should be modified to match the position as determined by NGS. It is presumed that the uncertainties in the refraction model are greater than the errors induced by not using an accurate location.
shane.par. Note the commentary in that file which questions the validity of this model and its parameters.
mosshane.parand code in
refract.F. The expression of the WCS does not match that used by any of the FITS WCS draft language. The parameters include: