WHT slew speeds
The telescope slews to a new position on the sky at approximately
1 deg/sec in each of azimuth and elevation,
with relatively short (few sec) overheads for acceleration and
The rotators on which the Cassegrain and prime-focus instruments are mounted
also slew at approximately 1 deg/sec. The Cassegrain rotator decelerates
slowly - total time for a rotation through theta deg is
~ theta + 30 sec.
The time taken to reach a new position is therefore often limited by the
movement in azimuth, which can take up to ~ 5 min.
The azimuth, elevation and Cassegrain rotator speeds were last measured
by Fiona Riddick in March 2016, and all three are about 1 deg/sec.