Space Telescope Imaging Spectrograph Instrument Handbook for Cycle 17

25MAMA-FUV-MAMA Clear

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Description

The 25MAMA mode with the FUV-MAMA detector provides high-throughput broad-band far-UV imaging with the highest available throughput at ~1500 Å and the highest possible spatial resolution. The field of view is 25x25 arcsec.

Recommended Uses

Recommended for broad-band near-UV imaging of sources where sky background is not a consideration.

Special Considerations

For long exposures of faint targets, sky background is likely to be a limiting factor. Observers should consider the use of DARKTIME or (preferably) use the F25QTZ filter, which has nearly the same throughput but rejects geocoronal Lyman- and [O I] 1302 + 1306 Å air glow.

Users may also want to consider whether the ACS SBC detector might be better for their observing program.

Pivot (Å)	FWHM (Å)	AB mag zero point	Speak	B	R80 (arcsec)	Flux in central pixel
1367.5	316.5	23.457	1.21e+14	341.9	0.32	8%

Figure 14.66: 25MAMA FUV-MAMA Integrated System Throughput and Redleak


 

Table 14.26: 25MAMA FUV-MAMA Sensitivity & Throughput

	Sensitivity	% Throughput
1150.	1.08E13	0.41
1175.	4.69E13	1.75
1200.	8.61E13	3.15
1225.	1.15E14	4.11
1250.	1.21E14	4.24
1275.	1.20E14	4.12
1300.	1.16E14	3.92
1325.	1.12E14	3.70
1350.	1.07E14	3.48
1375.	1.01E14	3.23
1400.	9.44E13	2.96
1425.	8.58E13	2.64
1450.	7.68E13	2.32
1475.	6.77E13	2.02
1500.	5.92E13	1.73
1525.	5.24E13	1.51
1550.	4.64E13	1.31
1575.	4.04E13	1.13
1600.	3.49E13	0.96
1625.	3.08E13	0.83
1650.	2.74E13	0.73
1675.	2.34E13	0.61
1700.	1.94E13	0.50
1725.	1.63E13	0.41
1750.	1.37E13	0.34
1775.	1.14E13	0.28
1800.	9.55E12	0.23
1825.	7.29E12	0.18
1850.	3.76E12	0.09

Figure 14.67: Point Source S/N vs. V+AB for the 25MAMA FUV-MAMA mode. Curves are labeled by required exposure time (sec).


 
Figure 14.68: Extended Source S/N vs. V+AB for the 25MAMA FUV-MAMA mode. Top curves are for an area of 0.2 arcsec²; bottom curves are for 1 arcsec². Average sky assumed. Curves are labeled by required exposure time (sec).


 

Table 14.27: Radial Profile for 25MAMA*

Radius			Fraction of Energy Encircled
Pixels	Arcsec	Intensity
1	0.024	3.267e-02	0.141
1.5	0.037	2.107e-02	0.236
2	0.049	1.345e-02	0.331
3	0.073	6.141e-03	0.467
4	0.098	2.981e-03	0.557
5	0.122	1.485e-03	0.614
10	0.245	3.377e-04	0.746
15	0.367	1.676e-04	0.834
20	0.490	9.542e-05	0.900
25	0.613	4.543e-05	0.947
30	0.735	2.065e-05	0.972
40	0.980	5.088e-06	0.994

* See STIS ISR 2003-01.

Figure 14.69: Point Source Encircled Energy for 25MAMA FUV-MAMA


 
Figure 14.70: Point Source Intensity vs. Radius for 25MAMA FUV-MAMA