Space Telescope Imaging Spectrograph Instrument Handbook for Cycle 17

F28X50OIII-CCD

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Description

The F28X50OIII mode is useful for narrow-band imaging of O III 5007 Å. The narrow bandpass and high spatial resolution provides some advantages over WFPC2 with the F502N filter, although the spatial resolution is not as high as that of ACS/HRC with its F502N filter.

Recommended Uses

Recommended for deep high-resolution O III imaging.

Special Considerations

This filter has a significant red leak longward of 1 micron. Depending on the source spectrum, the contribution from redleak may swamp the contribution from line emission.

Pivot (Å)	FWHM (Å)	AB mag zero point	Speak	B	R80 (arcsec)	Flux in central pixel
5005.8	6.2	18.755	1.16e+15	6.3	0.13	17%

Figure 14.12: Throughput for F28x50OIII.


 

Table 14.6: F28X50OIII Sensitivity & Throughput

	Sensitivity	% Throughput
4999.	4.81E13	0.42
5000.	1.12E14	0.99
5001.	1.92E14	1.69
5002.	3.69E14	3.24
5003.	5.93E14	5.21
5004.	8.50E14	7.46
5005.	1.12E15	9.85
5006.	1.16E15	10.13
5007.	1.03E15	9.01
5008.	8.03E14	7.04
5009.	4.98E14	4.36
5010.	2.73E14	2.39
5011.	1.29E14	1.13
5012.	4.82E13	0.42

Figure 14.13: Point Source S/N vs. V+AB for the F28X50OIII filter.Top curves are for low sky; bottom curves are for average sky. Curves are labeled by required exposure time (sec).


 
Figure 14.14: Extended Source S/N vs. V+AB for the F28X50OIII for gain=1. Top curves are for a source area of 0.2 arcsec²; bottom curves are for 1 arcsec². Average sky assumed. Curves are labeled by required exposure time (sec).


 

Table 14.7: Radial Profile for F28X50OIII

Radius			Fraction of Energy Encircled
Pixels	Arcsec	Intensity
1	0.050	1.750e-02	0.358
1.5	0.075	9.783e-03	0.574
2	0.100	4.193e-03	0.711
3	0.150	8.194e-04	0.844
4	0.200	3.245e-04	0.884
5	0.250	2.403e-04	0.916
10	0.500	2.049e-05	0.979
15	0.750	4.391e-06	0.995
20	1.000	8.462e-07	1.000

Figure 14.15: Point Source PSF for F28X50OIII, 7."5 square (pixel 493,542, log scaled, B-V=-0.34)


 
Figure 14.16: Point Source Encircled Energy for F28X50OIII


 
Figure 14.17: Point Source Intensity vs. Radius for F28X50OIII