7.7 Filter Induced Image Shifts

Most FOC filters in the visible band induce an image shift of over 7 pixels, or over 0.1", in an f/96 image. These effects can confuse the identification of an object imaged through different filters if the appropriate filter shifts are not taken into account. They can also make it difficult to obtain the proper offset for a dispersed prism image. Table 7.4 provides the observed filter shifts as seen in calibration data. The given offsets, good to +/- 1 pixel, are measured relative to the position an object would have through the F120M filter.

Filter Induced Image Shifts Relative to F120M Image
(good to +/- 1 pixel)

Filter	x Shift (pixels)	y Shift (pixels)
F120M	=0	=0
F130M	0	0
F140M	0	0
F140W	-1	2
F152M	0	0
F170M	0	0
F165W	1	1
F175W	-1	1
F190M	1	0
F210M	1	0
F220W	-1	2
F231M	1	-3
F253M	-1	3
F275W	-1	2
F278M	-2	4
F307M	-2	5
F320W	-73	46
F342W	-1	-2
F346M	-5	6
F372M	-4	6
F410M	-12	17
F430W	1	8
F370LP	0	2
F480LP	-1	1
F486N	-6	16
F501N	11	0
F502M	-1	-7
F600M	24	11
F550M	-1	-5
F1ND	0	0
F2ND	1	0
F4ND	0	-1
F6ND	0	0