Space Telescope Imaging Spectrograph Instrument Handbook for Cycle 17

F28X50OII-CCD

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Description

The F28X50OII mode is useful for narrow-band imaging of OII 3727 Å. The high throughput and high spatial resolution provide a significant advantage over WFPC2 imaging with the F375N filter for some purposes. The narrow bandpass may offer some advantages over ACS and either the HRC or WFC with the [O II] ramp filter.

Recommended Uses

Recommended for deep high-resolution O II imaging.

Special Considerations

This filter does not have a significant red leak. Flat field images taken through this filter show scattered light at the top and bottom of the frame. This is not expected to be a problem for astronomical targets

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Pivot (Å)	FWHM (Å)	AB mag zero point	Speak	B	R80 (arcsec)	Flux in central pixel
3738.1	56.9	20.522	3.43e+14	60.5	0.12	17%

Figure 14.18: Throughput for F28x50OII


 

Table 14.8: F28X50OII

	Sensitivity	% Throughput
3675.	6.26E12	0.07
3685.	3.31E13	0.39
3695.	9.81E13	1.17
3705.	1.63E14	1.93
3715.	2.23E14	2.63
3725.	2.67E14	3.14
3735.	2.48E14	2.91
3745.	2.65E14	3.10
3755.	3.12E14	3.64
3765.	2.89E14	3.37
3775.	1.42E14	1.65
3785.	2.77E13	0.32

Sensitivity & Throughput Figure 14.19: Point Source S/N vs. Line Flux for the F28X50OII filter. Top curves are for low sky; bottom curves are for average sky. Curves are labeled by required exposure time (sec).


 
Figure 14.20: Extended Source S/N vs. V+AB for the F28X50OII for gain =1.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 14.9: Radial Profile for F28X50OII

Radius			Fraction of Energy Encircled
Pixels	Arcsec	Intensity
1	0.050	1.945e-02	0.405
1.5	0.075	9.266e-03	0.622
2	0.100	3.589e-03	0.750
3	0.150	7.742e-04	0.849
4	0.200	3.628e-04	0.895
5	0.250	1.826e-04	0.924
10	0.500	1.966e-05	0.982
15	0.750	4.876e-06	0.997
20	1.000	5.800e-07	1.000

Figure 14.21: Point Source Encircled Energy for F28X50OII


 
Figure 14.22: Point Source Intensity vs. Radius for F28X50OII