Centering on objects using imaging mode

This is a variation on the initialization procedure above. It is the most precise method and essential for objects which are not visible in panoramic mode. It does have a significant overhead associated with it, however. Quicker methods are described later.

1.

Image the slit using the IRS, e.g.: ap to .35mm; mirror; go

2.

Measure the pixel position of the slit center on display.

3.

Image the field around the slit: ap to open_hole; go

Hopefully you see a star at this point.

4.

Set up guiding either of the object itself or another object. Turn follow on if it isn't already.

5.

Use offsets to center infrared star on previously measured slit position (0.32 arcsec/pixel); in effect using guider encoders for precision. The command recenter <xposition> <yposition> takes the current position in pixels and makes the required offsets. It is designed to work at an arbitrary rotation of the rotator.

6.

Now replace slit; disperse light and expose: ap to .35mm; lambda 2 2.2; go