Space Telescope Imaging Spectrograph Instrument Handbook for Cycle 17

F25MGII-NUV-MAMA

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Description

The F25MGII filter with the NUV-MAMA provides narrow-band imaging centered on the 2798 Å Mg II feature.

Recommended Uses

Narrowband imaging.

Special Considerations

There is a substantial redleak in this filter. Sources with a red underlying continuum may be difficult to observe. Users should be careful to take into account the underlying continuum in estimating whether the observation will fall within the bright object protection limits. This filter also has a complex PSF and exhibits several ghosts.

Figure 14.44: Point Source PSF for F25MGII NUV-MAMA 7."5 square (at pixel 316,658, log scaled, B-V=-0.04). Note psf ghost ~45 pixels left of peak pixel and a few 10^-3 of the peak, as well as the much more complex ghost about 10 pixels to the right of the central pixel.


 

Pivot (Å)	FWHM (Å)	AB mag zero point	Speak	B	R80 (arcsec)	Flux in central pixel
2801.7	47.7	19.449	7.78e+13	55.8	0.18	14%

Figure 14.45: F25MGII NUV-MAMA Integrated System Throughput and Redleak


 

Table 14.18: F25MGII NUV-MAMA Sensitivity & Throughput

	Sensitivity	% Throughput
2765.	9.39E12	0.15
2770.	2.92E13	0.46
2775.	6.05E13	0.96
2780.	6.51E13	1.03
2785.	6.25E13	0.98
2790.	6.23E13	0.98
2795.	6.31E13	0.99
2800.	6.94E13	1.09
2805.	7.66E13	1.20
2810.	7.54E13	1.18
2815.	6.74E13	1.05
2820.	6.28E13	0.98
2825.	6.62E13	1.03
2830.	5.13E13	0.80
2835.	2.09E13	0.32
2840.	7.23E12	0.11
2845.	3.13E12	0.05
2850.	1.64E12	0.03

Figure 14.46: Point Source S/N vs. V+AB for the F25MGII NUV-MAMA mode. Curves are labeled by required exposure time (sec).


 
Figure 14.47: Extended Source S/N vs. V+AB for the F25MGII 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 (sec).


 

Table 14.19: Radial Profile for F25MGII*

Radius			Fraction of Energy Encircled
Pixels	Arcsec	Intensity
1	0.024	5.302e-02	0.257
1.5	0.037	2.834e-02	0.391
2	0.049	1.466e-02	0.510
3	0.073	4.989e-03	0.641
4	0.098	1.739e-03	0.697
5	0.122	1.302e-03	0.738
10	0.245	2.035e-04	0.843
15	0.367	1.119e-04	0.899
20	0.490	3.763e-05	0.932
25	0.613	2.057e-05	0.949
30	0.735	1.692e-05	0.965
40	0.980	6.931e-06	0.988

* See STIS ISR 2003-01.

Figure 14.48: Point Source Encircled Energy for F25MGII NUV-MAMA


 
Figure 14.49: Point Source Intensity vs. Radius for F25MGII NUV-MAMA