25MAMA - NUV-MAMA, Clear

Description

The 25MAMA mode with the NUV-MAMA provides high-throughput broad-band near-ultraviolet (NUV) imaging with excellent pixel sampling and very high throughput at ~2500 Å.

Recommended Uses

Available (but not recommended, see below) for broad-band NUV imaging.

Special Considerations

NUV-MAMA clear images will be somewhat out of focus because the mirror optimally focuses for use of a filter. Whenever possible, use F25SRF2 or F25QTZ instead of 25MAMA for NUV-MAMA imaging.

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-α and [O I] 1302+1306 Å air glow.

Users should also consider whether WFC3 with the F225W, the F300X or the F275W filters might be a better choice for their science goals.

Pivot λ (Å)

FWHM (Å)

AB mag zero point

Speak

Bλ

R80 (arcsec)

Flux in central pixel

2260.6

1209.1

23.994

1.60e+14

1162.5

0.32

8%

Figure 14.23: 25MAMA NUV-MAMA Integrated System Throughput and Redleak



Table 14.10: 25MAMA NUV-MAMA Sensitivity & Throughput

λ

Sensitivity

% Throughput

1200.

7.83E12

0.29

1300.

1.96E13

0.66

1400.

2.96E13

0.93

1500.

3.62E13

1.06

1600.

3.76E13

1.03

1700.

3.98E13

1.03

1800.

4.93E13

1.20

1900.

6.57E13

1.52

2000.

8.95E13

1.96

2100.

1.14E14

2.39

2200.

1.36E14

2.71

2300.

1.48E14

2.82

2400.

1.53E14

2.81

2500.

1.57E14

2.75

2600.

1.59E14

2.69

2700.

1.56E14

2.54

2800.

1.49E14

2.34

2900.

1.23E14

1.86

3000.

9.38E13

1.37

3100.

4.61E13

0.65

Figure 14.24: Point Source S/N vs. V+ABν for the 25MAMA NUV-MAMA mode. Top curves are for DARKTIME. Bottom curves are for average sky. Curves are labeled by required exposure time (sec.).


Figure 14.25: Extended Source S/N vs. V+ABν for the 25MAMA NUV-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 (seconds).



Table 14.11: 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 14.26: Point Source Encircled Energy for 25MAMA NUV-MAMA


Figure 14.27: Point Source Intensity vs. Radius for 25MAMA NUV-MAMA