Space Telescope Science Institute  F25QTZ-FUV-MAMA, Longpass F25LYA-FUV-MAMA, Lyman-alpha

F25SRF2-FUV-MAMA, Longpass

Description

The F25SRF2 filter with the FUV-MAMA provides high-throughput broad-band far-UV imaging with better rejection of geocoronal emission than the F25MAMA but worse than F25QTZ modes. It provides the same field of view and spatial resolution as these modes.

Recommended Uses

This filter has slightly higher throughput than F25QTZ, but lets in geocoronal OI 1302 Å. For sky-limited imaging F25QTZ is usually a better choice.

Special Considerations

Sky background on the day side of the orbit contains a significant contributions from OI air glow emission at 1356 Å and at 1302 Å. In high-background conditions, the sky background can dominate the detector background. In average day-side observing conditions the sky background through this filter will be about a factor of 100 higher than for F25QTZ. Observers can limit the background (with some cost to the total amount of observing time per orbit) by using the DARKTIME special requirement.

Pivot (Å)
FWHM (Å)
AB mag zeropoint
Speak
B
R80 (arcsec)
Flux in central pixel
1457.4
283.7
22.825
8.67e+13
303.5
0.30
9%

Figure 14.83: F25SRF2 FUV-MAMA Integrated System Throughput and Redleak

 

Table 14.33: Throughput and Sensitivity for F25SRF2 FUV-MAMA
l
Sensitivity
Throughput %
1300.
7.18E13
2.42
1325.
8.60E13
2.85
1350.
8.66E13
2.82
1375.
8.53E13
2.72
1400.
8.30E13
2.60
1425.
7.82E13
2.41
1450.
7.27E13
2.20
1475.
6.69E13
1.99
1500.
6.07E13
1.78
1525.
5.47E13
1.58
1550.
4.90E13
1.39
1575.
4.30E13
1.20
1600.
3.73E13
1.02
1625.
3.25E13
0.88
1650.
2.84E13
0.76
1675.
2.43E13
0.64
1700.
1.99E13
0.51
1725.
1.68E13
0.43
1750.
1.42E13
0.36
1775.
1.19E13
0.29
1800.
9.96E12
0.24
Figure 14.84: Point Source S/N vs. V+AB for the F25SRF2 FUV-MAMA mode.

 
Figure 14.85: Extended Source S/N vs. V+AB for the F25SRF2 FUV-MAMA mode. Top curves are for an area of 0.2 arcsec2; bottom curves are for 1 arcsec2. Average sky assumed.

 

Table 14.34: Radial Profile for F25SRF2
Radius

Fraction of Energy Encircled
Pixels
Arcsec
Intensity
1
0.024
3.544e-02
0.154
2
0.037
2.268e-02
0.256
2
0.049
1.408e-02
0.358
3
0.073
5.787e-03
0.493
4
0.098
2.765e-03
0.576
5
0.122
1.514e-03
0.630
10
0.245
3.098e-04
0.762
15
0.367
1.677e-04
0.847
20
0.490
8.854e-05
0.910
25
0.613
4.487e-05
0.954
30
0.735
2.080e-05
0.980
40
0.980
1.510e-06
0.999
Figure 14.86: Point Source Encircled Energy for F25SRF2 FUV-MAMA

 
Figure 14.87: Point Source Intensity vs. Radius for F25SRF2 FUV-MAMA

 
F25QTZ-FUV-MAMA, Longpass F25LYA-FUV-MAMA, Lyman-alpha
Space Telescope Science Institute
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