Space Telescope Imaging Spectrograph Instrument Handbook for Cycle 17

CCD Clear Imaging-50CCD

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Description

The 50CCD mode is very sensitive for broad-band optical imaging. For a fixed exposure time, it can detect point sources roughly 0.8 mag fainter than with WFPC2 with the F606W filter. However, the ACS WFC with the F606W or F814W will be a better choice for most users.

Recommended Uses.

Recommended for deep imaging where detailed color information is not needed. In most cases the ACS WFC will be a better choice.

Special Considerations

Very red sources may show significant wings from detector halo (see Section 7.2.7)

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Pivot (Å)	FWHM (Å)	AB mag zero point	Speak	B	R80 (arcsec)	Flux in central pixel
5754.1	4333.0	26.295	2.03e+15	4930.6	0.16	14%

Figure 14.1: Throughput for 50CCD


 

Table 14.2: 50CCD Sensitivity & Throughput

	Sensitivity	% Throughput
2400.	1.41E14	2.59
2800.	1.97E14	3.08
3200.	3.64E14	4.99
3600.	5.01E14	6.05
4000.	9.33E14	10.24
4200.	1.15E15	12.00
4400.	1.30E15	12.98
4600.	1.41E15	13.44
4800.	1.51E15	13.83
5000.	1.60E15	14.06
5200.	1.68E15	14.21
5400.	1.79E15	14.52
5600.	1.88E15	14.74
5800.	1.94E15	14.68
6000.	1.98E15	14.50
6200.	2.01E15	14.26
6400.	2.03E15	13.93
6600.	2.02E15	13.45
6800.	1.99E15	12.84
7000.	1.94E15	12.16
7200.	1.88E15	11.45
7400.	1.81E15	10.76
7600.	1.73E15	9.99
7800.	1.60E15	9.02
8000.	1.46E15	7.99
8200.	1.33E15	7.12
8400.	1.23E15	6.41
8600.	1.17E15	5.98
9000.	1.14E15	5.55
9400.	1.06E15	4.96
9800.	7.95E14	3.56
10200.	3.93E14	1.69

Figure 14.2: Point Source S/N vs. V+AB for the 50CCD filter. Top curves are for low sky; bottom curves are for average sky. Curves are labeled by required exposure time (sec).


 
Figure 14.3: Extended Source S/N vs. V+AB for the 50CCD filter 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 14.3: Radial Profile for 50CCD

Radius			Fraction of Energy Encircled
Pixels	Arcsec	Intensity
1	0.050	1.614e-02	0.321
1.5	0.075	7.765e-03	0.495
2	0.100	4.320e-03	0.621
3	0.150	1.629e-03	0.787
4	0.200	4.904e-04	0.868
5	0.250	1.978e-04	0.902
10	0.500	2.499e-05	0.964
15	0.750	7.654e-06	0.986
20	1.000	2.687e-06	0.996

Figure 14.4: Point Source PSF for 50CCD, 7."5 square (at pixel 518,517, log scaled, B-V=-0.25).


 
Figure 14.5: Point Source Encircled Energy for 50CCD


 
Figure 14.6: Point Source Intensity vs. Radius for 50CCD