When an observer requests deployment in the focal plane of one of
ACAM's slits, the slit is positioned on the optical axis of ACAM,
but there are small slit-dependent differences in the exact position,
reflected as shifts in y position on the CCD, and tabulated below:
Slit width (arcsec) |
0.5 |
0.75 | 1.0 | 1.5 | 2.0 |
Shift (arcsec) |
0.62 | 0.34
| 0.00 | -0.17 | -0.24 |
The measurements were made on images of the back of each slit
taken through the Sloan g2 filter (#219), and the shifts are relative
to the measured position on the CCD of the 1.0-arcsec slit.