In spectroscopic mode UIST will only be used with the 0.12″/pixel plate scale.

The instrument has a 16-slot slit wheel which contains polarimetry masks, field stops and the slits for spectroscopy. The table below lists the slit wheel’s population.

1 March 2003 – 1 February 2006

Posn	Slit	Description	Ref
1	Small field stop (long cam)	1arcmin x 1arcmin square	V
2	X-disp 5pixel slit	0.60arcsec x 20arcsec	O
3	X-disp 7pixel slit	0.84arcsec x 20arcsec	Z
4	X-disp 3pixel slit	0.36arcsec x 20arcsec	M
5	Large field stop (short cam)	2arcmin x 2arcmin square	D
6	Long 4pixel slit	0.48arcsec x 120arcsec	K
7	Long 5pixel slit	0.60arcsec x 120arcsec	L
8	Long 2pixel slit	0.24arcsec x 120arcsec	I
9	Long 1pixel slit	0.12arcsec x 120arcsec	H
10	Long 7pixel slit	0.84arcsec x 120arcsec	Y
11	Pol mask imaging	Two slots 20arcsec x 120arcsec (170x1024pix)	F
12	Pol 2-pix spectroscopy	Two slots 0.24arcsec x 20arcsec	G
13	Pol 5-pix spectroscopy	Two slots 0.60arcsec x 20arcsec	X
14	2pixel pinhole	2pix x 2pix	B
15	large hole	—	N
16	IFU pick-off	5arcsec x 5arcsec square	—

Note: Datum switch region posns 5-10.

Previous slit wheel arrangement (Feb 2002 – Mar 2003) is available here.

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