Spectroscopic measurements made with CSHELL using the arc lamps and the 0.5" slit indicate that the maximum resolution achievable with CSHELL has degraded substantially from the nominal value. Resolutions of R = 20000 - 30000 are now reported, instead of the nominal value of 43000. This amounts to a broadening of 1-2 pixels over the expected value of 2.5 pixels.
It is not currently known what has caused this degradation of resolution. CSHELL is scheduled to be taken off the telescope during March-May for repairs, at which time the staff will attempt to re-focus the instrument.John Rayner
11 January 2000
LAST UPDATE: February 1, 2010 (format only)