Space Telescope Imaging Spectrograph Instrument Handbook for Cycle 17

0.2X0.2 Aperture

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Description

The "utility" slit for the echelle gratings. This slit is the most photometric of the supported echelle slits and has the highest throughput for photon statistics. Starting in Cycle 12, this slit is also supported for use with the first order gratings, and it is the recommended aperture for first order MAMA snapshot and survey programs that do not have a scientific need for a long-slit (see Section 2.8 STIS Snapshot and Survey Program Policies).

Table 13.25: 0.2X0.2 Throughputs

	% Throughput
1200	33.9
1800	67.0
2400	73.4
3000	77.1
3600	79.6
4200	81.5
4800	82.6
5400	82.9
6000	81.7

Aperture	Projected Length (arcsec) (MAMA E-modes)	Width (arcsec)
0.2X0.2	0.2	0.2

Figure 13.72: 0.2X0.2 Aperture Throughput as a Function of Wavelength