Aperture Offset Angles

The offset angle between the STIS aperture axis and the spacecraft orientation reference vector U3 is about 45 degress for the STIS spectroscopic apertures. However, observers should be aware that each STIS aperture has a specific U3 offset angle which is close to, but not equal to 45-degrees. In Table 1 we list the precise offset angles for all available spectroscopic slits. Uncertainties of the offset angles are typically +/- 0.05 degrees.

Table 1: Offset angles between the STIS spectroscopic apertures and the spacecraft orientation reference vector U3.
STIS Aperture	Offset Angle (degrees)	STIS Aperture	Offset Angle (degrees)
2X2	44.94	0.1X0.06	44.94
0.1X0.09	44.94	0.1X0.2	44.94
0.2X0.06	44.94	0.2X0.09	44.94
0.2X0.2	44.94	0.3X0.06	44.94
0.3X0.09	44.94	0.3X0.2	44.94
1X0.06	45.15	1X0.2	44.94
0.2X0.5	44.95	6X0.06	45.28
6X0.2	45.31	0.1X0.03	44.94
0.5X0.5	44.94	6X0.5	45.31
6X6	44.94	52X0.05	45.28
52X0.1	45.02	52X0.2	45.02
52X0.5	45.38	52X2	45.04
0.2X0.06FPA	44.94	0.2X0.06FPB	44.94
0.2X0.06FPC	44.94	0.2X0.06FPD	44.94
0.2X0.2FPE	44.94	0.2X0.2FPA	44.94
0.2X0.2FPB	44.94	0.2X0.2FPC	44.94
0.2X0.2FPD	44.94	0.2X0.2FPE	44.94
0.05X29	45.28	0.09X29	45.27
0.2X29	45.30	31X0.05NDA	45.27
31X0.05NDB	45.28	31X0.05NDC	45.28
0.3X0.05ND	44.95	0.2X0.05ND	44.94
0.05X31NDB	45.26	0.05X31NDA	45.29
52X0.05F1	46.55	52X0.05F2	44.00
52X0.1F1	46.28	52X0.1F2	43.73
52X0.2F1	46.30	52X0.2F2	43.74
52X0.5F1	46.65	52X0.5F2	44.10
52X2F1	46.31	52X2F2	43.75

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